gonetz
commented
2 months ago The current code uses the second nibble of the command to get the number of triangles. As you can see, in command 0x05110020, it is also 2. I checked, for command cmd, the second nibble is always equal to the sixth nibble + 1: ((cmd>>20)&15)+1) == ((cmd>>4)&15) But if the ucode actually uses value of the sixth nibble, ok.
if 0, texturing is set off. if 1, texturing is set on
I was not used. I added that code.
The rest is already implemented exactly as you described, see gSPDMATriangles function.
Fixed in commit b021d8ee4372. I don't expect any changes in Mickey Speedway USA and JFG, which use that ucode.
olivieryuyu
Checking out the ucode of Mickey Speedway USA, i went through command 0x05.
I am not sure that the implementation in Gliden64 matches it.
At the start of the command, the code checks this nibble:
05110020
if 0, texturing is set off.
if 1, texturing is set on
The number of triangles managed by this command is this nibble + 1
0x05110020
in this example it is therefore 2.
The code goes to the list retrieved from RDRAM to DMEM, decrementing the number of triangles to draw till 0.
data retrieved from RDRAM to DMEM has this structure
byte: mode byte: vtx0 byte: vtx1 byte: vtx2 word0: S&T0 word1: S&T1 word2: S1T2
the higher nibble of byte mode is either 4 or 0.
4 means that G_CULL_BACK in geomode is getting off.
0 means that G_CULL_BACK in geomode is getting on.
This is all what this command does for what i can understand from the code.