Add some shadow-related texture functions:

- C3D_TexShadowParams: configure GPUREG_TEXUNIT0_SHADOW
- C3D_TexInitShadow: create shadow map texture
- C3D_TexInitShadowCube: as above, but for shadow cubemaps

include/c3d/texture.h

@@ -58,6 +58,8 @@ void C3D_TexBind(int unitId, C3D_Tex* tex);
 void C3D_TexFlush(C3D_Tex* tex);
 void C3D_TexDelete(C3D_Tex* tex);
 
+void C3D_TexShadowParams(bool perspective, float bias);
+
 static inline int C3D_TexCalcMaxLevel(u32 width, u32 height)
 {
 	return (31-__builtin_clz(width < height ? width : height)) - 3; // avoid sizes smaller than 8
@@ -113,6 +115,18 @@ static inline bool C3D_TexInitVRAM(C3D_Tex* tex, u16 width, u16 height, GPU_TEXC
 		(C3D_TexInitParams){ width, height, 0, format, GPU_TEX_2D, true });
 }
 
+static inline bool C3D_TexInitShadow(C3D_Tex* tex, u16 width, u16 height)
+{
+	return C3D_TexInitWithParams(tex, NULL,
+		(C3D_TexInitParams){ width, height, 0, GPU_RGBA8, GPU_TEX_SHADOW_2D, true });
+}
+
+static inline bool C3D_TexInitShadowCube(C3D_Tex* tex, C3D_TexCube* cube, u16 width, u16 height)
+{
+	return C3D_TexInitWithParams(tex, cube,
+		(C3D_TexInitParams){ width, height, 0, GPU_RGBA8, GPU_TEX_SHADOW_CUBE, true });
+}
+
 static inline GPU_TEXTURE_MODE_PARAM C3D_TexGetType(C3D_Tex* tex)
 {
 	return (GPU_TEXTURE_MODE_PARAM)((tex->param>>28)&0x7);

source/base.c

@@ -71,6 +71,7 @@ bool C3D_Init(size_t cmdBufSize)
 	C3D_FragOpShadow(0.0, 1.0);
 
 	ctx->texConfig = BIT(12);
+	ctx->texShadow = BIT(0);
 	ctx->texEnvBuf = 0;
 	ctx->texEnvBufClr = 0xFFFFFFFF;
 
@@ -188,6 +189,7 @@ void C3Di_UpdateContext(void)
 	{
 		ctx->flags &= ~C3DiF_TexStatus;
 		GPUCMD_AddWrite(GPUREG_TEXUNIT_CONFIG,  ctx->texConfig);
+		GPUCMD_AddWrite(GPUREG_TEXUNIT0_SHADOW, ctx->texShadow);
 		ctx->texConfig &= ~BIT(16); // Remove clear-texture-cache flag
 	}
 

source/internal.h

@@ -39,6 +39,7 @@ typedef struct
 	C3D_LightEnv* lightEnv;
 
 	u32 texConfig;
+	u32 texShadow;
 	C3D_Tex* tex[3];
 	C3D_TexEnv texEnv[6];
 

source/texture.c

@@ -255,6 +255,20 @@ void C3D_TexDelete(C3D_Tex* tex)
 	tex->data = NULL;
 }
 
+void C3D_TexShadowParams(bool perspective, float bias)
+{
+	C3D_Context* ctx = C3Di_GetContext();
+
+	if (!(ctx->flags & C3DiF_Active))
+		return;
+
+	u32 iBias = (u32)(fabs(bias) * BIT(24));
+	if (iBias >= BIT(24))
+		iBias = BIT(24)-1;
+
+	ctx->texShadow = (iBias &~ 1) | (perspective ? 0 : 1);
+}
+
 void C3Di_SetTex(int unit, C3D_Tex* tex)
 {
 	u32 reg[10];