Add and Subtract blend modes for image tint

Author: KirbysDarkNebula

include/c2d/base.h

@@ -37,6 +37,8 @@ typedef enum
 	C2D_TintSolid, ///< Plain solid tint color
 	C2D_TintMult,  ///< Tint color multiplied by texture color
 	C2D_TintLuma,  ///< Tint color multiplied by grayscale converted texture color
+	C2D_TintAdd,  ///< Tint color added to the texture color
+	C2D_TintSub,  ///< Tint color subtracted from the texture color
 } C2D_TintMode;
 
 typedef struct

source/base.c

@@ -329,6 +329,12 @@ bool C2D_SetTintMode(C2D_TintMode mode)
 		case C2D_TintLuma:
 			new_mode = C2DiF_Mode_ImageLuma;
 			break;
+		case C2D_TintAdd:
+			new_mode = C2DiF_Mode_ImageAdd;
+			break;
+		case C2D_TintSub:
+			new_mode = C2DiF_Mode_ImageSub;
+			break;
 	}
 
 	ctx->flags = (ctx->flags &~ C2DiF_TintMode_Mask) | (new_mode << (C2DiF_TintMode_Shift - C2DiF_Mode_Shift));
@@ -714,6 +720,54 @@ void C2Di_Update(void)
 			C3D_TexEnvFunc(env, C3D_RGB, GPU_INTERPOLATE);
 			break;
 		}
+		case C2DiF_Mode_ImageAdd:
+		{
+			// Use texenv to blend the color source with the addition-tinted version of it,
+			// according to a parameter that is passed through with the help of proctex.
+			proctex = C2DiF_ProcTex_Blend;
+
+			// texenv0 = texclr + vtxcolor
+			env = C3D_GetTexEnv(0);
+			C3D_TexEnvInit(env);
+			C3D_TexEnvSrc(env, C3D_Both, GPU_TEXTURE0, GPU_PRIMARY_COLOR, GPU_PRIMARY_COLOR);
+			C3D_TexEnvFunc(env, C3D_RGB, GPU_ADD);
+
+			// texenv1.rgb = mix(texclr.rgb, texenv0.rgb, vtx.blend.y);
+			env = C3D_GetTexEnv(1);
+			C3D_TexEnvInit(env);
+			C3D_TexEnvSrc(env, C3D_RGB, GPU_TEXTURE0, GPU_PREVIOUS, GPU_TEXTURE3);
+			C3D_TexEnvOpRgb(env, GPU_TEVOP_RGB_SRC_COLOR, GPU_TEVOP_RGB_SRC_COLOR, GPU_TEVOP_RGB_ONE_MINUS_SRC_ALPHA);
+			C3D_TexEnvFunc(env, C3D_RGB, GPU_INTERPOLATE);
+
+			// Reset unused texenv stages
+			C3D_TexEnvInit(C3D_GetTexEnv(2));
+			C3D_TexEnvInit(C3D_GetTexEnv(3));
+			break;
+		}
+		case C2DiF_Mode_ImageSub:
+		{
+			// Use texenv to blend the color source with the subtraction-tinted version of it,
+			// according to a parameter that is passed through with the help of proctex.
+			proctex = C2DiF_ProcTex_Blend;
+
+			// texenv0 = texclr - vtxcolor
+			env = C3D_GetTexEnv(0);
+			C3D_TexEnvInit(env);
+			C3D_TexEnvSrc(env, C3D_Both, GPU_TEXTURE0, GPU_PRIMARY_COLOR, GPU_PRIMARY_COLOR);
+			C3D_TexEnvFunc(env, C3D_RGB, GPU_SUBTRACT);
+
+			// texenv1.rgb = mix(texclr.rgb, texenv0.rgb, vtx.blend.y);
+			env = C3D_GetTexEnv(1);
+			C3D_TexEnvInit(env);
+			C3D_TexEnvSrc(env, C3D_RGB, GPU_TEXTURE0, GPU_PREVIOUS, GPU_TEXTURE3);
+			C3D_TexEnvOpRgb(env, GPU_TEVOP_RGB_SRC_COLOR, GPU_TEVOP_RGB_SRC_COLOR, GPU_TEVOP_RGB_ONE_MINUS_SRC_ALPHA);
+			C3D_TexEnvFunc(env, C3D_RGB, GPU_INTERPOLATE);
+
+			// Reset unused texenv stages
+			C3D_TexEnvInit(C3D_GetTexEnv(2));
+			C3D_TexEnvInit(C3D_GetTexEnv(3));
+			break;
+		}
 	}
 
 	if (proctex && proctex != (ctx->flags & C2DiF_ProcTex_Mask))

source/internal.h

@@ -55,6 +55,8 @@ enum
 	C2DiF_Mode_ImageSolid = 3   << C2DiF_Mode_Shift,
 	C2DiF_Mode_ImageMult  = 4   << C2DiF_Mode_Shift,
 	C2DiF_Mode_ImageLuma  = 5   << C2DiF_Mode_Shift,
+	C2DiF_Mode_ImageAdd   = 6   << C2DiF_Mode_Shift,
+	C2DiF_Mode_ImageSub   = 7   << C2DiF_Mode_Shift,
 
 	C2DiF_ProcTex_Shift  = 12,
 	C2DiF_ProcTex_Mask   = 0xf << C2DiF_ProcTex_Shift,