Closed Dragorn421 closed 3 years ago
I had some hardware testing done for drawing triangles that used (combiner constants names in gbi.h) PRIM_LOD_FRAC (red, green tris) and LOD_FRACTION (blue tri) in the combiner, and used setPrimColor to change the lodFrac each frame
As expected angrylion shows the red and green tris fading in On hardware (no idea why stuff is black and white and messed up on this rom I made): https://streamable.com/ooauxg at 35s the same tris are fading in
So setPrimColor does set the value used by PRIM_LOD_FRAC and LOD_FRACTION is for something else
TLDR: angrylion is right, as always
Angrylion sets the primitive lod frac from the gDPSetPrimColor command:
https://github.com/ata4/angrylion-rdp-plus/blob/master/src/core/n64video/rdp/combiner.c#L507
However, what I read suggests that the setprimcolor command sets the "lod frac" and not the "primitive lod frac": Ocarina Of Time 64 wiki: https://wiki.cloudmodding.com/oot/F3DZEX2#Parameter_Description :
N64 manual uses "lod fraction" and not "primitive lod fraction" around
gDPSetPrimColor
: http://n64devkit.square7.ch/keywords/index/data/graphics.htm#primitive%20color%20register :http://n64devkit.square7.ch/pro-man/pro12/12-06.htm#02 :
My current guess is "lod frac" is just another value for use in the combiner, and "prim lod frac" is some kind of computed value (but according to what rules?). But Angrylion does the opposite.
So here I am, asking if whoever maintains this has more sources on what "lod frac" and "prim lod frac" do. Thanks in advance!