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Document fog functions Gfx_SetFog(2) and Play_SetFog

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Thar0 2024-03-08 03:09:54 +00:00
parent 68a86d2d00
commit df59993a94
2 changed files with 35 additions and 4 deletions
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4
src/code/z_play.c
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@ -173,6 +173,10 @@ void func_800BC88C(PlayState* this) {
this->transitionCtx.transitionType = -1;
}
/**
* Set the default fog state controlled by the environment system.
* If a custom fog state is used in rendering it is expected that it be reset back to this default state.
*/
Gfx* Play_SetFog(PlayState* this, Gfx* gfx) {
return Gfx_SetFog2(gfx, this->lightCtx.fogColor[0], this->lightCtx.fogColor[1], this->lightCtx.fogColor[2], 0,
this->lightCtx.fogNear, 1000);

35
src/code/z_rcp.c
View file

@ -847,28 +847,50 @@ Gfx gEmptyDL[] = {
gsSPEndDisplayList(),
};
/**
* Set fog color and range.
*
* At or prior to fog near, geometry is unaffected by fog. At or beyond fog far, geometry is fully fogged.
* Between near and far pixels will be linearly interpolated between the unfogged color and the supplied fog color.
*
* Fog far should be in the range 0 to 1000 and greater than or equal to fog near. If fog near is negative everything
* will be fully fogged. If fog near is 1000 or greater there is no fog.
*/
Gfx* Gfx_SetFog(Gfx* gfx, s32 r, s32 g, s32 b, s32 a, s32 near, s32 far) {
// Ensure fog far is greater than near
if (far == near) {
far++;
}
ASSERT(near != far, "n != f", "../z_rcp.c", 1155);
// Set the fog color, far away geometry will be rendered as this solid color.
gDPSetFogColor(gfx++, r, g, b, a);
if (near >= 1000) {
// Fog far is expected to be at most 1000 so near >= far. Set a constant shade alpha of 0 for no fog
gSPFogFactor(gfx++, 0, 0);
} else if (near >= 997) {
gSPFogFactor(gfx++, 0x7FFF, 0x8100);
} else if (near > 996) {
// Calculating the fog multiplier when far = 1000 and near >= 997 using `128000 / (far - near)` as in
// SPFogPosition would result in an overflow since 128000 / (1000 - 997) > 32767. Avoid this overflow by
// effectively clamping near to ~996. This is almost SPFogPosition(996.0937f, 1000)
gSPFogFactor(gfx++, 0x7FFF, -0x7F00); // Fixed point: 0x7FFF = 1.0, -0x7F00 = -0.992
} else if (near < 0) {
// Fog near is out of range. Set a constant shade alpha of 255 for fully fogged
gSPFogFactor(gfx++, 0, 255);
} else {
// Normal range. Shade alpha is 0 at z <= near and 255 at z >= far, linearly interpolated in between.
//! @bug If the difference between near and far is not at least 4, the fog multiplier will overflow. This is
//! handled above when fog far is 1000 but for closer fog far it is not accounted for.
gSPFogPosition(gfx++, near, far);
}
return gfx;
}
/**
* Like Gfx_SetFog but issues a pipesync before changing fog color.
*
* @see Gfx_SetFog
*/
Gfx* Gfx_SetFogWithSync(Gfx* gfx, s32 r, s32 g, s32 b, s32 a, s32 near, s32 far) {
if (far == near) {
far++;
@ -891,6 +913,11 @@ Gfx* Gfx_SetFogWithSync(Gfx* gfx, s32 r, s32 g, s32 b, s32 a, s32 near, s32 far)
return gfx;
}
/**
* Wrapper for Gfx_SetFog
*
* @see Gfx_SetFog
*/
Gfx* Gfx_SetFog2(Gfx* gfx, s32 r, s32 g, s32 b, s32 a, s32 near, s32 far) {
return Gfx_SetFog(gfx, r, g, b, a, near, far);
}