Reality Display Processor/Commands

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0 1 2 3 4 5 6 7
0x00 No Operation No Operation No Operation No Operation No Operation No Operation No Operation No Operation
0x08 Fill Triangle Fill Triangle (Z) Fill Triangle (T) Fill Triangle (TZ) Fill Triangle (S) Fill Triangle (SZ) Fill Triangle (ST) Fill Triangle (STZ)
0x10 No Operation No Operation No Operation No Operation No Operation No Operation No Operation No Operation
0x18 No Operation No Operation No Operation No Operation No Operation No Operation No Operation No Operation
0x20 No Operation No Operation No Operation No Operation Texture Rectangle Texture Rectangle Flip Sync Load Sync Pipe
0x28 Sync Tile Sync Full Set Key GB Set Key R Set Convert Set Scissor Set Primitive Depth Set Other Modes
0x30 Load TLUT No Operation Set Tile Size Load Block Load Tile Set Tile Fill Rectangle Set Fill Color
0x38 Set Fog Color Set Blend Color Set Primitive Color Set Environment Color Set Combine Mode Set Texture Image Set Depth Image Set Color Image

0x00 through 0x07, 0x10 through 0x23, 0x31 - No Operation


No Operation 0x00-0x07,0x10-0x23,0x31
63:48 command[5:0]
47:32
31:16
15:0
bit 61:56 command[5:0]: 0x00-0x07,0x10-0x23,0x31

Stalls the RDP pipeline for 1 cycle.

(TOVERIFY all of these command ids appear to behave as no-ops and take only 1 cycle to execute in testing so far, however this should be checked more extensively)

0x08 through 0x0F - Fill Triangle


The Fill Triangle command varies in length depending on whether shade, texture or depth is enabled in the first word. For any of these properties that are enabled, additional words are appended to the base command words in order of shading, texturing, z-buffering.

Base Command

Every triangle type begins with a common base that describes the type, shape and other small properties of the triangle.

Fill Triangle 0x08 through 0x0F (base)
Word 0 63:48 0 0 1 shade texture zbuffer lmajor level[2:0] tile[2:0]
47:32 yl[13:0]
31:16 ym[13:0]
15:0 yh[13:0]
Word 1 63:48 xl.i[11:0]
47:32 xl.f[15:0]
31:16 dxldy.i[13:0]
15:0 dxldy.f[15:0]
Word 2 63:48 xh.i[15:0]
47:32 xh.f[15:0]
31:16 dxhdy.i[15:0]
15:0 dxhdy.f[15:0]
Word 3 63:48 xm.i[15:0]
47:32 xm.f[15:0]
31:16 dxmdy.i[15:0]
15:0 dxmdy.f[15:0]

Word 0

bit 61:56 command: 0x08 through 0x0F depending on features specified
bit 58 shade: If 1, command is followed by 8 words specifying shading coefficients
bit 57 texture: If 1, command is followed by 8 words specifying texturing coefficients
bit 56 zbuffer: If 1, command is followed by 2 words specifying z-buffering coefficients
bit 55 lmajor: Left-major flag, if enabled rendering occurs from left-to-right, otherwise rendering occurs from right-to-left
bit 53:51 level[2:0]: Maximum LOD level
bit 50:48 tile[2:0]: Base tile descriptor index
bit 45:32 yl[13:0]: Lowest y coordinate (largest value), rasterization ends at this height (s11.2 format)
bit 29:16 ym[13:0]: Middle y coordinate (middle value), rasterization swaps dxmdy for dxldy (s11.2 format)
bit 13:0 yh[13:0]: Highest y coordinate (highest value), rasterization begins at this height (s11.2 format)

Word 1

bit 59:48 xl.i[11:0]: Integer part of x coordinate on dxldy line at height ym (s11.16 format)
bit 47:32 xl.f[15:0]: Fractional part of x coordinate on dxldy line at height ym (s11.16 format)
bit 29:16 dxldy.i[13:0]: Integer part of change in x per change in y of line connecting middle and lowest vertices (s13.16 format)
bit 15:0 dxldy.f[15:0]: Fractional part of change in x per change in y of line connecting middle and lowest vertices (s13.16 format)

Word 2

bit 59:48 xh.i[11:0]: Integer part of x coordinate on dxhdy line at height floor(yh) (s11.16 format)
bit 47:32 xh.f[15:0]: Fractional part of x coordinate on dxhdy line at height floor(yh) (s11.16 format)
bit 29:16 dxhdy.i[13:0]: Integer part of change in x per change in y of line connecting highest and lowest vertices (s13.16 format)
bit 15:0 dxhdy.f[15:0]: Fractional part of change in x per change in y of line connecting highest and lowest vertices (s13.16 format)

Word 3

bit 59:48 xm.i[11:0]: Integer part of x coordinate on dxmdy line at height floor(yh) (s11.16 format)
bit 47:32 xm.f[15:0]: Fractional part of x coordinate on dxmdy line at height floor(yh) (s11.16 format)
bit 29:16 dxmdy.i[13:0]: Integer part of change in x per change in y of line connecting highest and middle vertices (s13.16 format)
bit 15:0 dxmdy.f[15:0]: Fractional part of change in x per change in y of line connecting highest and middle vertices (s13.16 format)

Optional Shading Properties

If the shade bit was set in the base triangle description, the above words will be followed by these 8 words describing triangle shading properties:

Fill Shaded Triangle (suffix)
Word 0 63:48 - - - - - - - r.i[8:0]
47:32 - - - - - - - g.i[8:0]
31:16 - - - - - - - b.i[8:0]
15:0 - - - - - - - a.i[8:0]
Word 1 63:48 drdx.i[15:0]
47:32 dgdx.i[15:0]
31:16 dbdx.i[15:0]
15:0 dadx.i[15:0]
Word 2 63:48 r.f[15:0]
47:32 g.f[15:0]
31:16 b.f[15:0]
15:0 a.f[15:0]
Word 3 63:48 drdx.f[15:0]
47:32 dgdx.f[15:0]
31:16 dbdx.f[15:0]
15:0 dadx.f[15:0]
Word 4 63:48 drde.i[15:0]
47:32 dgde.i[15:0]
31:16 dbde.i[15:0]
15:0 dade.i[15:0]
Word 5 63:48 drdy.i[15:0]
47:32 dgdy.i[15:0]
31:16 dbdy.i[15:0]
15:0 dady.i[15:0]
Word 6 63:48 drde.f[15:0]
47:32 dgde.f[15:0]
31:16 dbde.f[15:0]
15:0 dade.f[15:0]
Word 7 63:48 drdy.f[15:0]
47:32 dgdy.f[15:0]
31:16 dbdy.f[15:0]
15:0 dady.f[15:0]

Word 0

bit 56:48 r.i[8:0]: Integer part of red channel shade color at (xh, floor(yh)) (s8.16 format)
bit 40:32 g.i[8:0]: Integer part of green channel shade color at (xh, floor(yh)) (s8.16 format)
bit 24:16 b.i[8:0]: Integer part of blue channel shade color at (xh, floor(yh)) (s8.16 format)
bit 8:0 a.i[8:0]: Integer part of alpha channel shade color at (xh, floor(yh)) (s8.16 format)

Word 1

bit 63:48 drdx.i[15:0]: Integer part of change in red channel shade color horizontally along a scanline (s15.16 format)
bit 47:32 dgdx.i[15:0]: Integer part of change in green channel shade color horizontally along a scanline (s15.16 format)
bit 31:16 dbdx.i[15:0]: Integer part of change in blue channel shade color horizontally along a scanline (s15.16 format)
bit 15:0 dadx.i[15:0]: Integer part of change in alpha channel shade color horizontally along a scanline (s15.16 format)

Word 2

bit 63:48 r.f[15:0]: Fractional part of red channel shade color at (xh, floor(yh)) (s8.16 format)
bit 47:32 g.f[15:0]: Fractional part of green channel shade color at (xh, floor(yh)) (s8.16 format)
bit 31:16 b.f[15:0]: Fractional part of blue channel shade color at (xh, floor(yh)) (s8.16 format)
bit 15:0 a.f[15:0]: Fractional part of alpha channel shade color at (xh, floor(yh)) (s8.16 format)

Word 3

bit 63:48 drdx.f[15:0]: Fractional part of change in red channel shade color horizontally along a scanline (s15.16 format)
bit 47:32 dgdx.f[15:0]: Fractional part of change in green channel shade color horizontally along a scanline (s15.16 format)
bit 31:16 dbdx.f[15:0]: Fractional part of change in blue channel shade color horizontally along a scanline (s15.16 format)
bit 15:0 dadx.f[15:0]: Fractional part of change in alpha channel shade color horizontally along a scanline (s15.16 format)

Word 4

bit 63:48 drde.i[15:0]: Integer part of change in red channel shade color along the major edge (s15.16 format)
bit 47:32 dgde.i[15:0]: Integer part of change in green channel shade color along the major edge (s15.16 format)
bit 31:16 dbde.i[15:0]: Integer part of change in blue channel shade color along the major edge (s15.16 format)
bit 15:0 dade.i[15:0]: Integer part of change in alpha channel shade color along the major edge (s15.16 format)

Word 5

bit 63:48 drdy.i[15:0]: Integer part of change in red channel shade color for each scanline (s15.16 format)
bit 47:32 dgdy.i[15:0]: Integer part of change in green channel shade color for each scanline (s15.16 format)
bit 31:16 dbdy.i[15:0]: Integer part of change in blue channel shade color for each scanline (s15.16 format)
bit 15:0 dady.i[15:0]: Integer part of change in alpha channel shade color for each scanline (s15.16 format)

Word 6

bit 63:48 drde.f[15:0]: Fractional part of change in red channel shade color along the major edge (s15.16 format)
bit 47:32 dgde.f[15:0]: Fractional part of change in green channel shade color along the major edge (s15.16 format)
bit 31:16 dbde.f[15:0]: Fractional part of change in blue channel shade color along the major edge (s15.16 format)
bit 15:0 dade.f[15:0]: Fractional part of change in alpha channel shade color along the major edge (s15.16 format)

Word 7

bit 63:48 drdy.f[15:0]: Fractional part of change in red channel shade color for each scanline (s15.16 format)
bit 47:32 dgdy.f[15:0]: Fractional part of change in green channel shade color for each scanline (s15.16 format)
bit 31:16 dbdy.f[15:0]: Fractional part of change in blue channel shade color for each scanline (s15.16 format)
bit 15:0 dady.f[15:0]: Fractional part of change in alpha channel shade color for each scanline (s15.16 format)

Optional Texturing Properties

If the texture bit was set in the base triangle description, the above words will be followed by these 8 words describing triangle texturing properties:

Fill Textured Triangle (suffix)
Word 0 63:48 s.i[15:0]
47:32 t.i[15:0]
31:16 w.i[15:0]
15:0
Word 1 63:48 dsdx.i[15:0]
47:32 dtdx.i[15:0]
31:16 dwdx.i[15:0]
15:0
Word 2 63:48 s.f[15:0]
47:32 t.f[15:0]
31:16 w.f[15:0]
15:0
Word 3 63:48 dsdx.f[15:0]
47:32 dtdx.f[15:0]
31:16 dwdx.f[15:0]
15:0
Word 4 63:48 dsde.i[15:0]
47:32 dtde.i[15:0]
31:16 dwde.i[15:0]
15:0
Word 5 63:48 dsdy.i[15:0]
47:32 dtdy.i[15:0]
31:16 dwdy.i[15:0]
15:0
Word 6 63:48 dsde.f[15:0]
47:32 dtde.f[15:0]
31:16 dwde.f[15:0]
15:0
Word 7 63:48 dsdy.f[15:0]
47:32 dtdy.f[15:0]
31:16 dwdy.f[15:0]
15:0

Word 0

bit 63:48 s.i[15:0]: Integer part of s-axis texture coordinate at (xh, floor(yh))
bit 47:32 t.i[15:0]: Integer part of t-axis texture coordinate at (xh, floor(yh))
bit 31:16 w.i[15:0]: Integer part of perspective scale at (xh, floor(yh))

Word 1

bit 63:48 dsdx.i[15:0]: Integer part of change in s-axis texture coordinate horizontally along a scanline
bit 47:32 dtdx.i[15:0]: Integer part of change in t-axis texture coordinate horizontally along a scanline
bit 31:16 dwdx.i[15:0]: Integer part of change in perspective scale horizontally along a scanline

Word 2

bit 63:48 s.f[15:0]: Fractional part of s-axis texture coordinate at (xh, floor(yh))
bit 47:32 t.f[15:0]: Fractional part of t-axis texture coordinate at (xh, floor(yh))
bit 31:16 w.f[15:0]: Fractional part of perspective scale at (xh, floor(yh))

Word 3

bit 63:48 dsdx.f[15:0]: Fractional part of change in s-axis texture coordinate horizontally along a scanline
bit 47:32 dtdx.f[15:0]: Fractional part of change in t-axis texture coordinate horizontally along a scanline
bit 31:16 dwdx.f[15:0]: Fractional part of change in perspective scale horizontally along a scanline

Word 4

bit 63:48 dsde.i[15:0]: Integer part of change in s-axis texture coordinate along the major edge
bit 47:32 dtde.i[15:0]: Integer part of change in t-axis texture coordinate along the major edge
bit 31:16 dwde.i[15:0]: Integer part of change in perspective scale along the major edge

Word 5

bit 63:48 dsdy.i[15:0]: Integer part of change in s-axis texture coordinate for each scanline
bit 47:32 dtdy.i[15:0]: Integer part of change in t-axis texture coordinate for each scanline
bit 31:16 dwdy.i[15:0]: Integer part of change in perspective scale for each scanline

Word 6

bit 63:48 dsde.f[15:0]: Fractional part of change in s-axis texture coordinate along the major edge
bit 47:32 dtde.f[15:0]: Fractional part of change in t-axis texture coordinate along the major edge
bit 31:16 dwde.f[15:0]: Fractional part of change in perspective scale along the major edge

Word 7

bit 63:48 dsdy.f[15:0]: Fractional part of change in s-axis texture coordinate for each scanline
bit 47:32 dtdy.f[15:0]: Fractional part of change in t-axis texture coordinate for each scanline
bit 31:16 dwdy.f[15:0]: Fractional part of change in perspective scale for each scanline

Optional Depth Properties

If the zbuffer bit was set in the base triangle description, the above words will be followed by these 2 words describing triangle depth properties:

Fill Z-Buffered Triangle (suffix)
Word 0 63:48 z.i[15:0]
47:32 z.f[15:0]
31:16 dzdx.i[15:0]
15:0 dzdx.f[15:0]
Word 1 63:48 dzde.i[15:0]
47:32 dzde.f[15:0]
31:16 dzdy.i[15:0]
15:0 dzdy.f[15:0]

Word 0

bit 63:48 z.i[15:0]: Integer part of depth at (xh, floor(yh))
bit 47:32 z.f[15:0]: Fractional part of depth at (xh, floor(yh))
bit 31:16 dzdx.i[15:0]: Integer part of change in depth horizontally along a scanline
bit 15:0 dzdx.f[15:0]: Fractional part of change in depth horizontally along a scanline

Word 1

bit 63:48 dzde.i[15:0]: Integer part of change in depth along the major edge
bit 47:32 dzde.f[15:0]: Fractional part of change in depth along the major edge
bit 31:16 dzdy.i[15:0]: Integer part of change in depth for each scanline
bit 15:0 dzdy.f[15:0]: Fractional part of change in depth for each scanline

0x24 and 0x25 - Texture Rectangle


Texture Rectangle 0x24 and Texture Rectangle Flip 0x25
Word 0 63:48 command[5:0] = 0x24 or 0x25 lrx[11:4]
47:32 lrx[3:0] lry[11:0]
31:16 tile[2:0] ulx[11:4]
15:0 ulx[3:0] uly[11:0]
Word 1 63:48 s[15:0]
47:32 t[15:0]
31:16 dsdx[15:0]
15:0 dtdy[15:0]

Word 0

bit 61:56 command[5:0]: 0x24 (Texture_Rectangle) or 0x25 (Texture_Rectangle_Flip)
bit 55:44 lrx[11:0]: Lower-right x screen coordinate (u10.2 format)
bit 43:32 lry[11:0]: Lower-right y screen coordinate (u10.2 format)
bit 26:24 tile[2:0]: Tile descriptor index
bit 23:12 ulx[11:0]: Upper-left x screen coordinate (u10.2 format)
bit 11:0 uly[11:0]: Upper-left y screen coordinate (u10.2 format)

Word 1

bit 63:48 s[15:0]: Upper-left s coordinate (s10.5 format)
bit 47:32 t[15:0]: Upper-left t coordinate (s10.5 format)
bit 31:16 dsdx[15:0]: Change in s per x (s5.10 format)
bit 15:0 dtdy[15:0]: Change in t per y (s5.10 format)

Renders a textured rectangle between upper-left coordinate (ulx,uly) and lower-right coordinate (lrx,lry), sampling texels using the tile descriptor indexed by tile. The coordinates (s,t) are the texture coordinates for the pixel at (ulx,uly), the derivatives dsdx and dtdy are added to these initial coordinates to determine the texture coordinates for every other pixel.

The screen coordinates are subpixel precise, integer values correspond to single pixels. In COPY and FILL mode the fractional bits are ignored and the lower-right bounds are inclusive, while in 1-Cycle and 2-Cycle modes the lower-right bounds are exclusive.

In COPY mode, since several pixels are written per cycle the dsdx parameter must account for this. It should be set such that it steps 64-bits worth of texels at a time, for example for a 16-bit color image it should be set to 4.0(s10.5) so that the s coordinate is incremented by 4 pixels (64 bits).

In FILL mode this behaves identically to Fill Rectangle, the texturing properties are ignored.

Internally, this command is equivalent to a left-major triangle where dxhdy = dxmdy = dxldy = 0, yl = ym = lry, yh = uly, xl = xm = lrx, xh = ulx

Hazards

  • In 1-Cycle and 2-Cycle mode using attributes such as shade color and per-pixel depth may be ill-defined. (TOVERIFY: It's either always 0 or uses the last value from previous primitives, check which)

0x26 - Sync Load


Sync Load 0x26
63:48 command = 0x26[5:0]
47:32
31:16
15:0
bit 61:56 command[5:0]: 0x26

Stalls the RDP pipeline for exactly 25 GCLK cycles. This guarantees that the loading pipeline will be available for use following any prior operation.

The stall is always 25 cycles and does not wait on any particular internal signal(s), if a Sync Load is queued when it is not needed it simply wastes the full length of time.

0x27 - Sync Pipe


Sync Pipe 0x27
63:48 command = 0x27[5:0]
47:32
31:16
15:0
bit 61:56 command[5:0]: 0x27

Stalls the RDP pipeline for exactly 50 GCLK cycles. This guarantees that any preceding primitives will be fully rendered and it is safe to modify rendering attributes such as color registers, othermodes and combine mode.

The stall is always 50 cycles and does not wait on any particular internal signal(s), if a Sync Pipe is queued when it is not needed it simply wastes the full length of time.

(TOVERIFY/Speculation: Changing an attribute without a sync typically corrupts only up to at most 24 pixels of the last primitive, suggesting the RDP pixel pipeline is ~24 cycles deep. Can a tile sync account for all or at least almost all attribute changes?)

0x28 - Sync Tile


Sync Tile 0x28
63:48 command = 0x28[5:0]
47:32
31:16
15:0
bit 61:56 command[5:0]: 0x28

Stalls the RDP pipeline for exactly 33 GCLK cycles. This guarantees that any preceding primitives will have finished using tile information and that it is now safe to modify tile descriptors without affecting prior primitives.

The stall is always 33 cycles and does not wait on any particular internal signal(s), if a Sync Tile is queued when it is not needed it simply wastes the full length of time.

0x29 - Sync Full


Sync Full 0x29
63:48 command = 0x29[5:0]
47:32
31:16
15:0
bit 61:56 command[5:0]: 0x29

Waits for all currently staged pipeline and memory operations to complete before halting the RDP pipeline counter and raising the DP interrupt in the MIPS Interface.

Hazards

  • Ensure this is the final command consumed before hitting DP_END, otherwise the RDP may hang.
  • Ensure no other commands are sent to RDP (via DP_START/DP_END) while a Sync Full is in progress, otherwise the RDP may hang.

0x2A - Set Key GB


Set Key GB 0x2a
63:48 command = 0x2a[5:0] width_G[11:4]
47:32 width_G[3:0] width_B[11:0]
31:16 center_G[7:0] scale_G[7:0]
15:0 center_B[7:0] scale_B[7:0]
bit 61:56 command[5:0]: 0x2a
bit 55:44 width_G[11:0]: Keying window half-width for green channel (4.8 format)
bit 43:32 width_B[11:0]: Keying window half-width for blue channel (4.8 format)
bit 31:24 center_G[7:0]: Center Color Combiner input for green channel
bit 23:16 scale_G[7:0]: Scale Color Combiner input for green channel
bit 15:8 center_B[7:0]: Center Color Combiner input for blue channel
bit 7:0 scale_B[7:0]: Scale Color Combiner input for blue channel

Sets chroma Key parameters for the green and blue color channels.

Key width is used exclusively in the chroma key pipeline stage following the Color Combiner (if enabled in othermodes)

Key center and scale are Color Combiner inputs, the expectation is that the Color Combiner is configured to when chroma keying, where is any color source. If not chroma keying, these may be used as general-purpose Color Combiner inputs.

0x2B - Set Key R


Set Key R 0x2b
63:48 command = 0x2b[5:0]
47:32
31:16 width_R[11:0]
15:0 center_R[7:0] scale_R[7:0]
bit 61:56 command[5:0]: 0x2b
bit 27:16 width_R[11:0]: Keying window half-width for red channel (4.8 format)
bit 15:8 center_R[7:0]: Center Color Combiner input for red channel
bit 7:0 scale_R[7:0]: Scale Color Combiner input for red channel

Sets Chroma Key parameters for the red color channel. See Set Key GB for discussion.

0x2C - Set Convert


Set Convert 0x2c
63:48 command = 0x2c[5:0] K0[8:3]
47:32 K0[2:0] K1[8:0] K2[8:5]
31:16 K2[4:0] K3[8:0] K4[8:7]
15:0 K4[6:0] K5[8:0]
bit 61:56 command[5:0]: 0x2c
bit 53:45 K0[8:0]: Color conversion constant K0
bit 44:36 K1[8:0]: Color conversion constant K1
bit 35:27 K2[8:0]: Color conversion constant K2
bit 26:18 K3[8:0]: Color conversion constant K3
bit 17:9 K4[8:0]: Color conversion constant K4
bit 8:0 K5[8:0]: Color conversion constant K5

Sets colorspace conversion coefficients intended for YUV -> RGB conversion.

K0 through K3 are used in the Texture Filter color conversion step:

K4 and K5 are made available as Color Combiner inputs, with the intention that the CC complete the colorspace conversion process after receiving values from the Texture Filter.

K4 and K5 may also simply be used as additional general-purpose CC inputs.

0x2D - Set Scissor


Set Scissor 0x2d
63:48 command = 0x2d[5:0] upper_left.x[11:4]
47:32 upper_left.x[3:0] upper_left.y[11:0]
31:16 field odd lower_right.x[11:4]
15:0 scissor.x.lo[3:0] lower_right.y[11:0]
bit 61:56 command[5:0]: 0x2d
bit 55:44 upper_left.x[11:0]: Upper left x coordinate (u10.2 format)
bit 43:32 upper_left.y[11:0]: Upper left y coordinate (u10.2 format)
bit 25 field: Whether to perform interlaced rendering, only even or odd lines will be processed
bit 24 odd: Whether to keep even (0) or odd (1) lines when interlaced rendering is enabled
bit 23:12 lower_right.x[11:0]: Lower right x coordinate (u10.2 format)
bit 11:0 lower_right.y[11:0]: Lower right y coordinate (u10.2 format)

Sets the scissor region, pixels that are outside of this region will not be processed in the pixel pipeline and will not be written to memory. Note that only the scissor determines this, the color image width has no effect. Typically the scissor width should not be larger than the color image width.

The RDP is capable of efficiently rejecting pixels that lie outside the left, right and lower scissor boundaries at no cost in time. The same cannot be said of pixels lying above the scissor region: for every line for which a primitive extends above the scissor region the RDP spends one cycle advancing each line, since it must update the attribute start values for each line.

Hazards

  • The scissor region is inclusive on the lower-right edges in FILL and COPY modes, while it is exclusive on the lower-right edges in 1-Cycle and 2-Cycle modes.
  • The scissor region must be configured before rendering anything. There is no way to disable the scissor, if it is not configured it will use whatever configuration was last in the registers.
  • In COPY mode, upper_left.x should be 0 (TOVERIFY Is this always true? It appears to be an unavoidable crash, but needs further investigation)
  • In COPY mode, lower_right.x should be a multiple of 4 pixels (-1) to prevent possible memory corruption
  • In FILL mode, upper_left.x and lower_right.x should be multiples of 4 pixels (-1 for lower_right.x) to prevent possible memory corruption
  • FILL mode triangles interact bizarrely with the scissor bounds, avoid drawing such triangles that extend off-screen (TODO understand this better)
  • In FILL mode sometimes scissor works at the level of individual pixels while sometimes it only works at 4-pixel boundaries. (TODO understand this better, probably to do with memory alignment)

0x2E - Set Primitive Depth


Set Primitive Depth 0x2e
63:48 command = 0x2e[5:0]
47:32
31:16 z[15:0]
15:0 dz[15:0]
bit 61:56 command[5:0]: 0x2e
bit 31:16 z[15:0]: Primitive depth value
bit 15:0 dz[15:0]: Primitive dz value

Sets the primitive depth registers to the provided values. Primitive depth may be selected for depth compare instead of using per-pixel depth in the othermodes configuration. This is the only way to set a depth value for rectangle commands.

When used, the primitive depth value is taken to be the integer part of the s15.3 fixed-point z value, the fractional bits will be zero. Notably, due to not having control over the fractional bits it is impossible to configure a primitive depth value that writes the maximum possible depth value into the z-buffer.

Unlike the majority of other attribute-setters, primitive depth operates correctly even in the absence of pipeline synchronizations. Primitive depth may be changed between primitive rendering without corrupting prior primitives.

Hazards

  • The dz value provided should be a power of 2 to ensure correct operation. RDP hardware uses a cheap integer log2 algorithm for computing log2(dz) that is only guaranteed to produce correct results when the input is a power of 2. Notably, the value 0xFFFF happens to work correctly.

0x2F - Set Other Modes


Set Other Modes 0x2f
63:48 command = 0x2f[5:0] atomic_prim - cycle_type[1:0] persp_tex_en detail_tex_en sharpen_tex_en tex_lod_en
47:32 tlut_en tlut_type sample_type mid_texel bi_lerp_0 bi_lerp_1 convert_one key_en rgb_dither_sel[1:0] alpha_dither_sel[1:0] -
31:16 bl_m1a_0[1:0] bl_m1a_1[1:0] bl_m1b_0[1:0] bl_m1b_1[1:0] bl_m2a_0[1:0] bl_m2a_1[1:0] bl_m2b_0[1:0] bl_m2b_1[1:0]
15:0 - force_blend alpha_cvg_select cvg_x_alpha z_mode[1:0] cvg_dest[1:0] color_on_cvg image_read_en z_update_en z_compare_en antialias_en z_source_sel dither_alpha_en alpha_compare_en
bit 61:56 command[5:0]: 0x2f
bit 55 atomic_prim: Enables span buffer coherency, forces active span segments to be written to the frame buffer before reading new span segments
bit 54 -: ?
bit 53:52 cycle_type[1:0]: Determines pipeline mode. Either 1-Cycle (0), 2-Cycle (1), COPY (2), FILL (3)
bit 51 persp_tex_en: Enables perspective correction of texture coordinates
bit 50 detail_tex_en: Enables "detail texture" mode in Texture LOD
bit 49 sharpen_tex_en: Enables "sharpen texture" mode in Texture LOD
bit 48 tex_lod_en: Enables Texture Level of Detail (LOD)
bit 47 tlut_en: Enables Texture Look-Up Table (TLUT) sampling. Texels are first fetched from low TMEM that are then used to index a palette in high TMEM to find the final color values.
bit 46 tlut_type: Determines TLUT texel format. Either RGBA16 (0) or IA16 (1)
bit 45 sample_type: Determines texel sampling mode. Either point-sampled (0) or 2x2 bilinear (1)
bit 44 mid_texel: Determines bilinear filter mode. Either 3-point (0) or average mode (1)
bit 43 bi_lerp_0: Determines texture filter mode for the first cycle. Either YUV to RGB conversion (See Set Convert) (0) or bilinear filter (1)
bit 42 bi_lerp_1: Determines texture filter mode for the second cycle. Either YUV to RGB conversion (See Set Convert) (0) or bilinear filter (1)
bit 41 convert_one: Determines the input to the second texture filter stage. Either the sample from the second stage of texture sampling (0) or the result from the first texture filter cycle (1)
bit 40 key_en: Enables chroma keying following the Color Combiner stage
bit 39:38 rgb_dither_sel[1:0]: Set RGB dither mode
bit 37:36 alpha_dither_sel[1:0]: Set Alpha dither mode
bit 35:32 -: ?
bit 31:30 bl_m1a_0[1:0]: Blender input P (first cycle)
bit 29:28 bl_m1a_1[1:0]: Blender input P (second cycle)
bit 27:26 bl_m1b_0[1:0]: Blender input A (first cycle)
bit 25:24 bl_m1b_1[1:0]: Blender input A (second cycle)
bit 23:22 bl_m2a_0[1:0]: Blender input M (first cycle)
bit 21:20 bl_m2a_1[1:0]: Blender input M (second cycle)
bit 19:18 bl_m2b_0[1:0]: Blender input B (first cycle)
bit 17:16 bl_m2b_1[1:0]: Blender input B (second cycle)
bit 15 -: ?
bit 14 force_blend: Enables blending for all pixels rather than only edge pixels
bit 13 alpha_cvg_select: Use coverage (or coverage multiplied by CC alpha) for alpha input to blender rather than alpha output from CC
bit 12 cvg_x_alpha: Multiply coverage and alpha from CC (used in conjunction with alpha_cvg_sel)
bit 11:10 z_mode[1:0]: Determines z-buffer comparator mode
bit 9:8 cvg_dest[1:0]: Determines coverage output mode
bit 7 color_on_cvg: If enabled, writes the blender output only if coverage overflowed, otherwise write the 2B input verbatim
bit 6 image_read_en: Enable color image reading
bit 5 z_update_en: Enable z-buffer writing
bit 4 z_compare_en: Enable z-buffer reading and depth comparison
bit 3 antialias_en: Enable anti-aliasing, which may enable blending on edge pixels
bit 2 z_source_sel: Selects either per-pixel (0) or primitive (1) depth as depth source to compare against the z-buffer
bit 1 dither_alpha_en: Determines alpha compare threshold source. (0 blend color register alpha, 1 random)
bit 0 alpha_compare_en: Enables alpha compare, pixels below the alpha threshold (compared against CC alpha output) are not written

Configures the RDP "Other Modes", a collection of global settings.

RGB dither modes

Value Description
0 4x4 Magic Square dither matrix
1 4x4 Bayer dither matrix
2 Random noise
3 Disabled, no dithering applied

Alpha dither modes

Value Description
0 Same pattern as chosen in RGB. If noise was chosen, use magic square. If RGB dither was disabled, use bayer.
1 Inverse of the same pattern as chosen in RGB. Same rules as above if RGB was noise or disabled.
2 Random noise
3 Disabled, no dithering applied

Z modes

Value Description
0 Opaque surface mode.
1 Interpenetrating surface mode.
2 Transparent surface mode.
3 Decal surface mode.

Coverage destination modes

Value Description
0 Clamp. Sums new and old coverage, clamps to full if there is an overflow.
1 Wrap. Sums new and old coverage, writes this sum modulo 8.
2 Full. Always write full coverage.
3 Save. Always write old coverage, discard new coverage. Requires image_read_en, otherwise it will behave like Full.

Blender Configuration

Other modes include the blender input configuration. The blender computes either

or

The latter is performed only when force_blend is disabled and anti-aliasing is enabled, where it is performed only on edge pixels.

Blender P and M Inputs

Value Description
0 First cycle: output color from Color Combiner final stage; Second cycle: output color from first blender cycle
1 Memory color from framebuffer
2 Blend color register RGB
3 Fog color register RGB

Blender A Inputs

Value Description
0 Output alpha from Color Combiner final stage
1 Fog color register Alpha
2 Shade Alpha (interpolated per-pixel)
3 Fixed 0.0

Blender B Inputs

Value Description
0 1.0 - A, where A is the other alpha input
1 Memory coverage from framebuffer
2 Fixed 1.0
3 Fixed 0.0

Hazards

  • This is a pipeline configuration command that requires pipeline synchronization before use, otherwise currently rendering primitives may be partially rendered using both the old other modes configuration and the new other modes configuration.
  • Blender hazards:
    • If memory color was set as a blender input, image_read_en should be enabled for proper operation.
    • If memory coverage was set as a blender input, image_read_en should be enabled for proper operation. If it is left disabled, memory coverage is set to full.
    • 2-Cycle mode pipeline bug: In the first cycle of 2-cycle mode, memory color is read from the previous pixel.
    • 2-Cycle mode pipeline bug: In the first cycle of 2-cycle mode, memory coverage is read from the previous pixel.
    • 2-Cycle mode pipeline bug: In the second cycle of 2-cycle mode, shade alpha is read from the next pixel.

0x30 - Load TLUT


Load TLUT 0x30
63:48 command = 0x34[5:0] upper_left.s[11:4]
47:32 upper_left.s[3:0] upper_left.t[11:0]
31:16 tile[2:0] lower_right.s[11:4]
15:0 lower_right.s[3:0] lower_right.t[11:0]
bit 61:56 command[5:0]: 0x30
bit 55:44 upper_left.s[11:0]: Upper-left s coordinate (u10.2)
bit 43:32 upper_left.t[11:0]: Upper-left t coordinate (u10.2)
bit 26:24 tile[2:0]: Tile descriptor index
bit 23:12 lower_right.s[11:0]: Lower-right s coordinate (u10.2)
bit 11:0 lower_right.t[11:0]: Lower-right t coordinate (u10.2)

Loads a Texture Look-Up Table (TLUT) into TMEM.

When loading with Load TLUT, every texel loaded from RDRAM is quadrupled and placed adjacently in TMEM. A 256-color TLUT therefore takes up bytes of TMEM, which is the maximum size of a TLUT as it must fit in high TMEM. A 16-color TLUT takes up only bytes of TMEM, 16 of these may reside in high TMEM at the same time.

Typical usage of Load TLUT may resemble (uls=0, ult=0, lrs=count-1, lrt=0) where count is the number of texels making up the TLUT, e.g. 255 for a 256-color palette.

Hazards

  • For correct sampling, the base TMEM address for a TLUT must reside in the upper half of TMEM, that is at TMEM word address 0x100 (byte address 0x800) or greater.
  • For correct sampling, the base TMEM address for a TLUT must be aligned to 16 TMEM words or 128 bytes.

0x32 - Set Tile Size


Set Tile Size 0x32
63:48 command = 0x32[5:0] upper_left.s[11:4]
47:32 upper_left.s[3:0] upper_left.t[11:0]
31:16 index[2:0] lower_right.s[11:4]
15:0 lower_right.s[3:0] lower_right.t[11:0]
bit 61:56 command[5:0]: 0x32
bit 55:44 upper_left.s[11:0]: Upper-left s coordinate (u10.2 format)
bit 43:32 upper_left.t[11:0]: Upper-left t coordinate (u10.2 format)
bit 26:24 index[2:0]: Tile descriptor index
bit 23:12 lower_right.s[11:0]: Lower-right s coordinate (u10.2 format)
bit 11:0 lower_right.t[11:0]: Lower-right t coordinate (u10.2 format)

Updates the tile extents for the tile descriptor specified by the index parameter.

The upper-left coordinate specifies the origin of the tile, where texture coordinates (0,0) would sample from, and sets the lower extents for clamp/mask/mirror in texture sampling.

The lower-right coordinate specifies the upper extents for clamp/mask/mirror in texture sampling.

0x33 - Load Block


Load Block 0x33
63:48 command = 0x33[5:0] upper_left.s[11:4]
47:32 upper_left.s[3:0] upper_left.t[11:0]
31:16 tile[2:0] lower_right.s[11:4]
15:0 lower_right.s[3:0] dxt[11:0]
bit 61:56 command[5:0]: 0x33
bit 55:44 upper_left.s[11:0]: Upper-left s coordinate (u10.2)
bit 43:32 upper_left.t[11:0]: Upper-left t coordinate (u10.2)
bit 26:24 tile[2:0]: Tile descriptor index
bit 23:12 lower_right.s[11:0]: Lower-right s coordinate (u10.2)
bit 11:0 dxt[11:0]: Change in x per t (u1.11)

Load Block loads texels to the TMEM address specified by the selected tile descriptor from the RDRAM location pointed to by the current texture image (see Set Texture Image).

Only 2048 texels of any size can be loaded at once, loads configured to read more than 2048 texels will fail resulting in nothing being written into TMEM. For 4 and 8 bit types the texture image texel size can be set to 16-bit to facilitate loading more than 2048 texels, it is not possible to use the 32-bit texel size in this way without advance preparation as 32-bit texels have a different TMEM layout. lower_right.s - upper_left.s determines the number of texels to load.

Load Block is the fastest way to move data from RDRAM into TMEM, however not all width/height combinations are valid. Texture lines loaded with Load Block must be a multiple of 64 bits in size, either naturally or by explicitly padding each line in RDRAM. Further, for a given width there is a maximum height based on imprecision in the dxt value. For each 64-bit TMEM word loaded with Load Block, an internal counter is incremented by dxt. This counter can be thought of as a 1.11 fixed-point value; when the counter holds a value greater than one the current word being loaded belongs to an odd-numbered line, otherwise it belongs to an even-numbered line. For texture sampling reasons odd lines must have their 32-bit words swapped when loaded from RDRAM, this is done automatically by the loading hardware hence why it tracks which lines are even or odd. However if dxt is sufficiently imprecise the counter may miss a word at the end of a line, leading to corruptions as that word will not be swapped correctly.

Hazards

  • Some texture image addresses may hang the RDP if an attempt is made to load from it. See Set Texture Image hazards.
  • Load Block sets the tile size for the associated tile descriptor to (upper_left.s, upper_left.t, lower_right.s, dxt). This is generally not a useful configuration for rendering the image.

0x34 - Load Tile


Load Tile 0x34
63:48 command = 0x34[5:0] upper_left.s[11:4]
47:32 upper_left.s[3:0] upper_left.t[11:0]
31:16 tile[2:0] lower_right.s[11:4]
15:0 lower_right.s[3:0] lower_right.t[11:0]
bit 61:56 command[5:0]: 0x34
bit 55:44 upper_left.s[11:0]: Upper-left s coordinate (u10.2)
bit 43:32 upper_left.t[11:0]: Upper-left t coordinate (u10.2)
bit 26:24 tile[2:0]: Tile descriptor index
bit 23:12 lower_right.s[11:0]: Lower-right s coordinate (u10.2)
bit 11:0 lower_right.t[11:0]: Lower-right t coordinate (u10.2)

Load Tile loads an arbitrary rectangle of texels to the TMEM address specified by the selected tile descriptor from the RDRAM location pointed to by the current texture image (see Set Texture Image). The rectangle in RDRAM to load from is specified by the provided upper_left and lower_right coordinates and the line parameter in the tile descriptor, the RDRAM width is lower_right.s - upper_left.s while the TMEM width is the tile line parameter. The upper_left location in RDRAM is mapped to the tile TMEM address.

Load Tile is slower than Load Block, however it is more flexible as there is no need to explicitly pad texture lines in RDRAM to 8-byte boundaries, and there are no issues with word-swapping.

Load Tile updates the tile size for the selected tile descriptor to (upper_left.s, upper_left.t, lower_right.s, lower_right.t) which may be used for subsequent rendering.

Hazards

  • The texel size specified in Set Texture Image should match the texel size in the tile descriptor used for loading, otherwise operation is not guaranteed.
  • Loads that extend past the end of TMEM will wrap back to the start.

0x35 - Set Tile


Set Tile 0x35
63:48 command = 0x35[5:0] format[2:0] size[1:0] line[8:7]
47:32 line[6:0] address[8:0]
31:16 index[2:0] palette[3:0] clamp_T mirror_T mask_T[3:2]
15:0 mask_T[1:0] shift_T[3:0] clamp_S mirror_S mask_S[3:0] shift_S[3:0]
bit 61:56 command[5:0]: 0x35
bit 55:53 format[2:0]: Tile texel format
bit 52:51 size[1:0]: Tile texel size
bit 49:41 line[8:0]: Tile line length in TMEM words
bit 40:32 address[8:0]: TMEM address in TMEM words
bit 26:24 index[2:0]: Tile index
bit 23:20 palette[3:0]: Palette index
bit 19 clamp_T: Clamp enable (T-axis)
bit 18 mirror_T: Mirror enable (T-axis)
bit 17:14 mask_T[3:0]: Mask (T-axis)
bit 13:10 shift_T[3:0]: Shift (T-axis)
bit 9 clamp_S: Clamp enable (S-axis)
bit 8 mirror_S: Mirror enable (S-axis)
bit 7:4 mask_S[3:0]: Mask (S-axis)
bit 3:0 shift_S[3:0]: Shift (S-axis)

Configures the tile descriptor specified by the index parameter.

The texel format parameter is selected from

Format Name Format Value
RGBA 0
YUV 1
Color-Indexed (CI) 2
Intensity-Alpha (IA) 3
Intensity (I) 4+

The texel size parameter is selected from

Bits per pixel Size Value
4 0
8 1
16 2
32 3

Officially supported format/size combinations

RGBA YUV CI IA I
4 - - checkY checkY checkY
8 - - checkY checkY checkY
16 checkY checkY - checkY -
32 checkY - - - -

The line parameter indicates the number of TMEM (64-bit) words in a single row of the tile. This quantity is typically calculated from the tile width in texels and texel size as (width * NBITS(size) + 63) / 64 where NBITS(size) is the number of bits per texel. If a texture width is not an integral number of TMEM words, each row must be padded to begin on a new TMEM word; Load Tile performs this padding transparently when loading texture data from RDRAM into TMEM, for Load Block the data must already be padded in RDRAM.

The address is a TMEM word (64-bit) address. For example an address of 0x100 resolves to byte address 0x800, half way through TMEM.

The palette parameter is for CI4 formatted tiles, for CI formats of other sizes it is ignored altogether. It is the upper half of a TMEM address, indicating where the tile can find the associated color palette. The lower half of the TMEM address is populated by the color index in the CI4 texture data.

The clamp/mirror/mask/shift parameters for each texture coordinate axis influence how texels are sampled from the tile during texture sampling. (TODO link texture sampling article)

  • clamp: Enables clamping. When the tile is sampled with coordinates that fall outside the tile boundaries, the nearest texel that is within the tile bounds will be used. If disabled, coordinates are brought into the tile range by wrapping based on the mask value, which operates on powers of 2. Therefore, if a tile extent is not a power of 2 clamping should typically be used.
  • mirror: Enables mirroring. When oversampling the tile, flip the axis.
  • mask: Determines how many bits of the integer part of the texture coordinate should be considered for sampling from this tile. A mask of 0 indicates all bits should be considered.
  • shift: Optional shift amount for texture coordinates. Values 1-10 shift right while 11-15 shift left.
Shift value Operation
0 N/A
1 >> 1
2 >> 2
...
10 >> 10
11 << 5
12 << 4
13 << 3
14 << 2
15 << 1

0x36 - Fill Rectangle


Fill Rectangle 0x36
63:48 command = 0x36[5:0] lower_right.x[11:4]
47:32 lower_right.x[3:0] lower_right.y[11:0]
31:16 upper_left.x[11:4]
15:0 upper_left.x[3:0] upper_left.y[11:0]
bit 61:56 command[5:0]: 0x36
bit 55:44 lower_right.x[11:0]: Lower-right x coordinate (u10.2 format)
bit 43:32 lower_right.y[11:0]: Lower-right y coordinate (u10.2 format)
bit 23:12 upper_left.x[11:0]: Upper-left x coordinate (u10.2 format)
bit 11:0 upper_left.y[11:0]: Upper-right y coordinate (u10.2 format)

Renders a solid-color rectangle.

In FILL and COPY mode, the rectangle coordinates are inclusive on the right and lower edges while in 1-Cycle and 2-Cycle mode they are exclusive.

In 1-Cycle or 2-Cycle mode, the rectangle is rendered with subpixel accuracy and can be anti-aliased if pixels are only partially covered. The color is determined by the blender output as with triangles and texture rectangles, not the fill color register.

In FILL mode, the rectangle is rendered without subpixel accuracy (upper-left coordinates are rounded down, lower-right coordinates are rounded up) and the color is determined solely by the fill color register.

Internally, this command is equivalent to a left-major triangle where dxhdy = dxmdy = dxldy = 0, yl = ym = lry, yh = uly, xl = xm = lrx, xh = ulx

Hazards

  • In 1-Cycle and 2-Cycle mode using attributes such as shade color, texture coordinates and per-pixel depth may be ill-defined. (TOVERIFY: It's either always 0 or uses the last value from previous primitives, check which)
  • In COPY mode, fill rectangle behaves like texture rectangle with all texture attributes (tile, s, t, dsdx, dtdy) set to 0. (TOVERIFY: as above, is it always 0 or is it left over values from previous primitives?)

0x37 - Set Fill Color


Set Fill Color 0x37
63:48 command = 0x37[5:0]
47:32
31:16 color[31:16]
15:0 color[15:0]
bit 61:56 command[5:0]: 0x37
bit 31:0 color[31:0]: Fill Color. Format varies based on color image pixel size, see below

Sets the fill color register, the color to use when rendering primitives in FILL mode. This is the only color sampled by FILL mode as all other pipeline stages are bypassed. This color is not made available to the Color Combiner or the Blender, and Fill Rectangle outside of FILL mode does not use it.

Since FILL mode simply repeats the 32-bit value verbatim out to memory, proper usage of the color parameter will depend on the color image configuration:

  • 32-bit: A single RGBA32 color occupying all 32 bits.
  • 16-bit: Two RGBA16 colors occupying the upper and lower 16 bits respectively. Even pixels sample the upper half and odd pixels sample the lower half. For filling the color image with a solid color, simply let the upper and lower halves hold the same value.
  • 8-bit: Four 8-bit intensity values, repeating every four pixels.
  • 4-bit: N/A, crash

Hazards

  • This is an attribute-setting command that requires pipeline synchronization before use, otherwise currently rendering primitives may be partially rendered using both the old fill color and the new fill color, if it was used.

0x38 - Set Fog Color


Set Fog Color 0x38
63:48 command = 0x38[5:0]
47:32
31:16 red[7:0] green[7:0]
15:0 blue[7:0] alpha[7:0]
bit 61:56 command[5:0]: 0x38
bit 31:24 red[7:0]: Fog Red Value
bit 23:16 green[7:0]: Fog Green Value
bit 15:8 blue[7:0]: Fog Blue Value
bit 7:0 alpha[7:0]: Fog Alpha Value

Sets the "Fog" color register to the provided RGBA value. This color is accessible from the Blender as an input.

The name "Fog" reflects only one particular usage of how the color may be used, the name does not relate to any particular meaning in the hardware.

Hazards

  • This is an attribute-setting command that requires pipeline synchronization before use, otherwise currently rendering primitives may be partially rendered using both the old fog color and the new fog color, if it was used.

0x39 - Set Blend Color


Set Blend Color 0x39
63:48 command = 0x39[5:0]
47:32
31:16 red[7:0] green[7:0]
15:0 blue[7:0] alpha[7:0]
bit 61:56 command[5:0]: 0x39
bit 31:24 red[7:0]: Blend Red Value
bit 23:16 green[7:0]: Blend Green Value
bit 15:8 blue[7:0]: Blend Blue Value
bit 7:0 alpha[7:0]: Blend Alpha Value

Sets the "Blend" color register to the provided RGBA value. This color is accessible from the Blender as an input.

The name "Blend" reflects only one particular usage of how the color may be used, the name does not relate to any particular meaning in the hardware.

Hazards

  • This is an attribute-setting command that requires pipeline synchronization before use, otherwise currently rendering primitives may be partially rendered using both the old blend color and the new blend color, if it was used.

0x3A - Set Primitive Color


Set Primitive Color 0x3a
63:48 command = 0x3a[5:0]
47:32 min_level[7:0] prim_lod_frac[7:0]
31:16 red[7:0] green[7:0]
15:0 blue[7:0] alpha[7:0]
bit 61:56 command[5:0]: 0x3a
bit 47:40 min_level[7:0]: Minimum LOD level
bit 39:32 prim_lod_frac[7:0]: Primitive LOD Fraction Color Combiner input
bit 31:24 red[7:0]: Primitive Red Value
bit 23:16 green[7:0]: Primitive Green Value
bit 15:8 blue[7:0]: Primitive Blue Value
bit 7:0 alpha[7:0]: Primitive Alpha Value

Sets the "Primitive" color register to the provided RGBA value, and some LOD parameters. The color is accessible from the Color Combiner as an input.

The name "Primitive" reflects only one particular usage of how the color may be used, the name does not relate to any particular meaning in the hardware.

prim_lod_frac is simply another Color Combiner input, despite the name it is not used by the texture LOD hardware feature. It may be used as a fixed interpolation factor.

min_level is used in the texture LOD hardware, it bounds the LOD tile selection from below. The LOD value selecting a particular tile N can be computed by

where Tbase is the tile number set in the triangle command. For texture rectangles this is tile 0.

If the LOD computed for a particular pixel during texture sampling is less than the minimum LOD level, tile 0 is used. Detail and sharpen modes may still apply. (TODO link to more detailed Texture LOD article)

Unlike the majority of other attribute-setters, primitive color operates correctly even in the absence of pipeline synchronizations. The primitive color may be changed between primitive rendering without corrupting prior primitives.

0x3B - Set Environment Color


Set Environment Color 0x3b
63:48 command = 0x3b[5:0]
47:32
31:16 red[7:0] green[7:0]
15:0 blue[7:0] alpha[7:0]
bit 61:56 command[5:0]: 0x3b
bit 31:24 red[7:0]: Environment Red value
bit 23:16 green[7:0]: Environment Green value
bit 15:8 blue[7:0]: Environment Blue value
bit 7:0 alpha[7:0]: Environment Alpha value

Sets the "Environment" color register to the provided RGBA value. This color is accessible from the Color Combiner as an input.

The name "Environment" reflects only one particular usage of how the color may be used, the name does not relate to any particular meaning in the hardware.

Hazards

  • This is an attribute-setting command that requires pipeline synchronization before use, otherwise currently rendering primitives may be partially rendered using both the old environment color and the new environment color, if it was used.

0x3C - Set Combine Mode


Set Combine Mode 0x3c
63:48 command = 0x3c[5:0] RGB_A_0[3:0] RGB_C_0[4:1]
47:32 RGB_C_0[0] Alpha_A_0[2:0] Alpha_C_0[2:0] RGB_A_1[3:0] RGB_C_1[4:0]
31:16 RGB_B_0[3:0] RGB_B_1[3:0] Alpha_A_1[2:0] Alpha_C_1[2:0] RGB_D_0[2:1]
15:0 RGB_D_0[0] Alpha_B_0[2:0] Alpha_D_0[2:0] RGB_D_1[2:0] Alpha_B_1[2:0] Alpha_D_1[2:0]
bit 61:56 command[5:0]: 0x3c
bit 55:52 RGB_A_0[3:0]: RGB A Input (First Cycle)
bit 51:47 RGB_C_0[4:0]: RGB C Input (First Cycle)
bit 46:44 Alpha_A_0[2:0]: Alpha A Input (First Cycle)
bit 43:41 Alpha_C_0[2:0]: Alpha C Input (First Cycle)
bit 40:37 RGB_A_1[3:0]: RGB A Input (Second Cycle)
bit 36:32 RGB_C_1[4:0]: RGB C Input (Second Cycle)
bit 31:28 RGB_B_0[3:0]: RGB B Input (First Cycle)
bit 27:24 RGB_B_1[3:0]: RGB B Input (Second Cycle)
bit 23:21 Alpha_A_1[2:0]: Alpha A Input (Second Cycle)
bit 20:18 Alpha_C_1[2:0]: Alpha C Input (Second Cycle)
bit 17:15 RGB_D_0[2:0]: RGB D Input (First Cycle)
bit 14:12 Alpha_B_0[2:0]: Alpha B Input (First Cycle)
bit 11:9 Alpha_D_0[2:0]: Alpha D Input (First Cycle)
bit 8:6 RGB_D_1[2:0]: RGB D Input (Second Cycle)
bit 5:3 Alpha_B_1[2:0]: Alpha B Input (Second Cycle)
bit 2:0 Alpha_D_1[2:0]: Alpha D Input (Second Cycle)

Configures the inputs to the Color Combiner pipeline stage. The Color Combiner stage computes the following equation

This equation can be configured differently for

  • Cycle 1 RGB
  • Cycle 1 Alpha
  • Cycle 2 RGB
  • Cycle 2 Alpha

In 1-Cycle mode only the Cycle 2 configuration is computed, while in 2-Cycle mode both are computed and the output from Cycle 1 can be used as an input to Cycle 2. Besides some inputs behaving differently the second cycle of 2-Cycle mode and the only cycle of 1-Cycle mode behave identically, the first cycle of 2-Cycle mode is greatly simplified with no clamping occurring between combiner cycles.

Inputs for A (RGB)

Value Name Description
0 COMBINED Combined color from first cycle
1 TEX0 Texture color sampled from the tile set in the primitive command, after texture LOD if enabled
2 TEX1 Texture color sampled from the tile set in the primitive command, after texture LOD if enabled, plus one
3 PRIMITIVE Primitive color register (rgb)
4 SHADE Shade color interpolated per-pixel from shade coefficients
5 ENVIRONMENT Environment color register (rgb)
6 1 Fixed 1
7 NOISE Per-pixel noise
8+ 0 Fixed 0

Inputs for A (Alpha)

Value Name Description
0 COMBINED Combined alpha from first cycle
1 TEX0 Texture alpha sampled from the tile set in the primitive command, after texture LOD if enabled
2 TEX1 Texture alpha sampled from the tile set in the primitive command, after texture LOD if enabled, plus one
3 PRIMITIVE Primitive color register (alpha)
4 SHADE Shade alpha interpolated per-pixel from shade coefficients
5 ENVIRONMENT Environment color register (alpha)
6 1 Fixed 1
7 0 Fixed 0

Inputs for B (RGB)

Value Name Description
0 COMBINED Combined color from first cycle
1 TEX0 Texture color sampled from the tile set in the primitive command, after texture LOD if enabled
2 TEX1 Texture color sampled from the tile set in the primitive command, after texture LOD if enabled, plus one
3 PRIMITIVE Primitive color register (rgb)
4 SHADE Shade color interpolated per-pixel from shade coefficients
5 ENVIRONMENT Environment color register (rgb)
6 CENTER Chroma key center (see Set Key R and Set Key GB)
7 K4 K4 value (see Set Convert)
8+ 0 Fixed 0

Inputs for B (Alpha)

Value Name Description
0 COMBINED Combined alpha from first cycle
1 TEX0 Texture alpha sampled from the tile set in the primitive command, after texture LOD if enabled
2 TEX1 Texture alpha sampled from the tile set in the primitive command, after texture LOD if enabled, plus one
3 PRIMITIVE Primitive color register (alpha)
4 SHADE Shade alpha interpolated per-pixel from shade coefficients
5 ENVIRONMENT Environment color register (alpha)
6 1 Fixed 1
7 0 Fixed 0

Inputs for C (RGB)

Value Name Description
0 COMBINED Combined color from first cycle
1 TEX0 Texture color sampled from the tile set in the primitive command, after texture LOD if enabled
2 TEX1 Texture color sampled from the tile set in the primitive command, after texture LOD if enabled, plus one
3 PRIMITIVE Primitive color register (rgb)
4 SHADE Shade color interpolated per-pixel from shade coefficients
5 ENVIRONMENT Environment color register (rgb)
6 CENTER Chroma key center (see Set Key R and Set Key GB)
7 COMBINED_ALPHA Combined alpha from first cycle
8 TEX0_ALPHA Texture alpha sampled from the tile set in the primitive command, after texture LOD if enabled
9 TEX1_ALPHA Texture alpha sampled from the tile set in the primitive command, after texture LOD if enabled, plus one
10 PRIMITIVE_ALPHA Primitive color register (alpha)
11 SHADE_ALPHA Shade alpha interpolated per-pixel from shade coefficients
12 ENVIRONMENT_ALPHA Environment color register (alpha)
13 LOD_FRACTION LOD Fraction computed as part of Texture LOD
14 PRIM_LOD_FRAC Primitive LOD Fraction (see Set Primitive Color)
15 K5 K5 value (see Set Convert)
16+ 0 Fixed 0

Inputs for C (Alpha)

Value Name Description
0 LOD_FRACTION LOD Fraction computed as part of Texture LOD
1 TEX0 Texture alpha sampled from the tile set in the primitive command, after texture LOD if enabled
2 TEX1 Texture alpha sampled from the tile set in the primitive command, after texture LOD if enabled, plus one
3 PRIMITIVE Primitive color register (alpha)
4 SHADE Shade alpha interpolated per-pixel from shade coefficients
5 ENVIRONMENT Environment color register (alpha)
6 PRIM_LOD_FRAC Primitive LOD Fraction (see Set Primitive Color)
7 0 Fixed 0

Inputs for D (RGB)

Value Name Description
0 COMBINED Combined color from first cycle
1 TEX0 Texture color sampled from the tile set in the primitive command, after texture LOD if enabled
2 TEX1 Texture color sampled from the tile set in the primitive command, after texture LOD if enabled, plus one
3 PRIMITIVE Primitive color register (rgb)
4 SHADE Shade color interpolated per-pixel from shade coefficients
5 ENVIRONMENT Environment color register (rgb)
6 1 Fixed 1
7 0 Fixed 0

Inputs for D (Alpha)

Value Name Description
0 COMBINED Combined alpha from first cycle
1 TEX0 Texture alpha sampled from the tile set in the primitive command, after texture LOD if enabled
2 TEX1 Texture alpha sampled from the tile set in the primitive command, after texture LOD if enabled, plus one
3 PRIMITIVE Primitive color register (alpha)
4 SHADE Shade alpha interpolated per-pixel from shade coefficients
5 ENVIRONMENT Environment color register (alpha)
6 1 Fixed 1
7 0 Fixed 0

Hazards

  • This is a pipeline configuration command that requires pipeline synchronization before use, otherwise currently rendering primitives may be partially rendered using both the old combiner configuration and the new combiner configuration.
  • In 1-Cycle mode only the second cycle configuration is used, the first cycle configuration is ignored.
  • COMBINED in the first cycle (or in 1-Cycle mode) is ill-defined. It will (generally) read the previous pixel combiner output.
  • If using the SHADE input the primitive must have provided shade coefficients. The SHADE input is therefore always invalid for rectangle commands as there is no option for providing shade coefficients for those.
  • If using the TEX0/1 inputs the primitive must have provided texture coordinates and a tile number. Fill Rectangles cannot provide either of these so these options are always invalid for those.
  • If using the LOD_FRACTION input, Texture LOD must have been enabled in othermodes.
  • In 1-Cycle mode, LOD_FRACTION is not valid. (TOVERIFY in what way is it not valid? Does the 1-Cycle pipeline bypass LOD altogether, so does not update this input?)
  • In 1-Cycle mode, TEX1 reads next pixel TEX0 (with some ambiguity at scanline edges)
  • In 2-Cycle mode there is a pipeline bug involving TEX0 and TEX1. In the second cycle of 2-Cycle mode, TEX0 refers to TEX1 and TEX1 refers to next pixel TEX0 (with some ambiguity at scanline edges)
  • The color combiner is quick to overflow. Values between 256 and 383 saturate to 255 while 384 to 511 overflow to 0. Values greater than or equal to 512 overflow the 9-bit color completely.
  • Sign-extension properties differ between the A,B,D and C inputs. C is more prone to overflow, it is advisable to keep the COMBINED input out of the C input as much as possible.
  • The 1 input is valued at 256, not 255. This may contribute to overflow issues.

0x3D - Set Texture Image


Set Texture Image 0x3d
63:48 command = 0x3d[5:0] format[2:0] size[1:0]
47:32 width[9:0]
31:16 dramAddress[23:16]
15:0 dramAddress[15:0]
bit 61:56 command[5:0]: 0x3d
bit 55:53 format[2:0]: Texture image format
bit 52:51 size[1:0]: Texture image pixel size
bit 41:32 width[9:0]: Texture image width in pixels (-1) (possible range of 1 to 4096 pixels)
bit 23:0 dramAddress[23:0]: RDRAM physical address of the buffer containing texture data

Sets the texture image, the location in RDRAM where the texture loading pipeline should source image data, and related properties.

The texture image format parameter seems to have no function, it has no effect on any operation unlike the tile format.

Format Name Format Value
RGBA 0
YUV 1
Color-Indexed (CI) 2
Intensity-Alpha (IA) 3
Intensity (I) 4+

The size parameter is used to increment the RDRAM address during texture loading.

Bits per pixel Size Value
4 0
8 1
16 2
32 3

The width parameter is used to calculate the start address of each texture image row during loading.

This is an attribute-setting command but is not used in the rendering pipeline so does not require a pipeline synchronization before changing it. (TOVERIFY is a sync required if changing it following a load command?)

Hazards

  • Memory alignment should be 8-byte to guarantee operation. If the address falls into the range [1,7] mod 64, the RDP may hang when loading from it.

0x3E - Set Depth Image


Set Depth Image 0x3e
63:48 command = 0x3e[5:0]
47:32
31:16 dramAddress[23:16]
15:0 dramAddress[15:0]
bit 61:56 command[5:0]: 0x3e
bit 23:0 dramAddress[23:0]: RDRAM physical address of the buffer to store depth information

Sets the depth image, the region in RDRAM where depth information will be stored. The depth image width is the same as the image width for the current color image. The depth buffer format is a fixed 18-bit-per-pixel format irrespective of the color image format.

Hazards

  • This attribute must be set before rendering any primitives that read or write depth, else it will read/write depth data at an unspecified location.
  • Memory alignment must be 64-byte for all rendering operations to behave as expected.

0x3F - Set Color Image


Set Color Image 0x3f
63:48 command = 0x3f[5:0] format[2:0] size[1:0]
47:32 width[9:0]
31:16 dramAddress[23:16]
15:0 dramAddress[15:0]
bit 61:56 command[5:0]: 0x3f
bit 55:53 format[2:0]: Pixel format (same meaning as in texture format)
bit 52:51 size[1:0]: Pixel size (same meaning as in texture size)
bit 41:32 width[9:0]: Image width in pixels (-1) (possible range of 1 to 4096 pixels)
bit 23:0 dramAddress[23:0]: RDRAM physical address of the buffer where pixels will be written

Sets the color image address and properties, the region in RDRAM where primitives will be rendered to as pixels.

The image is arrayed in row-order, that is rows are adjacent in memory. It is generally more efficient to draw wide triangles rather than horizontally thin triangles that overlap many rows; for single rows span buffers are employed to alleviate stalls due to waiting on memory read/write requests while there is no such buffering across multiple rows.

Valid format/size combinations are RGBA32, RGBA16, I8. 4-bit modes only write 0s as bytes, all 8-bit modes behave identically, 16-bit and 32-bit RGBA modes differ from other modes.

Hazards

  • This attribute must be set before rendering any primitives, else it will render to an unspecified location.
  • This is an attribute-setting command that requires pipeline synchronization before use, otherwise currently rendering primitives may be split partially between the old color image and new color image. (TOVERIFY there are conflicting accounts of whether Set Color Image requires a sync, the current consensus is that sync is required to avoid all edge cases)
  • Memory alignment must be 64-byte for all rendering operations to behave as expected.
  • Rendering any primitive in FILL mode to a 4-bit color image will crash the RDP.
  • Copying a 4-bit or 8-bit texture with COPY mode is only possible if the destination color image is 8-bit.
  • Copying a 16-bit texture with COPY mode is only possible if the destination color image is 16-bit. (Note that CI textures are treated as 16-bit in COPY mode as the TLUT is 16-bit)
  • COPY mode is unavailable when a 32-bit color image is configured.