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improved blending accuracy to fix Glean test failures

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Brian Paul 2000-10-19 18:08:05 +00:00
parent 6aafd2491c
commit cc50ed60b3
1 changed files with 39 additions and 19 deletions
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58
src/mesa/main/blend.c
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@ -1,10 +1,10 @@
/* $Id: blend.c,v 1.18 2000/09/07 15:45:27 brianp Exp $ */
/* $Id: blend.c,v 1.19 2000/10/19 18:08:05 brianp Exp $ */
/*
* Mesa 3-D graphics library
* Version: 3.3
* Version: 3.5
*
* Copyright (C) 1999 Brian Paul All Rights Reserved.
* Copyright (C) 1999-2000 Brian Paul All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
@ -354,11 +354,31 @@ blend_transparency( GLcontext *ctx, GLuint n, const GLubyte mask[],
/* 100% alpha, no-op */
}
else {
#if 0
/* This is pretty close, but Glean complains */
const GLint s = CHAN_MAX - t;
const GLint r = (rgba[i][RCOMP] * t + dest[i][RCOMP] * s) >> 8;
const GLint g = (rgba[i][GCOMP] * t + dest[i][GCOMP] * s) >> 8;
const GLint b = (rgba[i][BCOMP] * t + dest[i][BCOMP] * s) >> 8;
const GLint a = (rgba[i][ACOMP] * t + dest[i][ACOMP] * s) >> 8;
const GLint r = (rgba[i][RCOMP] * t + dest[i][RCOMP] * s + 1) >> 8;
const GLint g = (rgba[i][GCOMP] * t + dest[i][GCOMP] * s + 1) >> 8;
const GLint b = (rgba[i][BCOMP] * t + dest[i][BCOMP] * s + 1) >> 8;
const GLint a = (rgba[i][ACOMP] * t + dest[i][ACOMP] * s + 1) >> 8;
#elif 0
/* This is slower but satisfies Glean */
const GLint s = CHAN_MAX - t;
const GLint r = (rgba[i][RCOMP] * t + dest[i][RCOMP] * s) / 255;
const GLint g = (rgba[i][GCOMP] * t + dest[i][GCOMP] * s) / 255;
const GLint b = (rgba[i][BCOMP] * t + dest[i][BCOMP] * s) / 255;
const GLint a = (rgba[i][ACOMP] * t + dest[i][ACOMP] * s) / 255;
#else
/* This satisfies Glean and should be reasonably fast */
/* Contributed by Nathan Hand */
#define DIV255(X) (((X) << 8) + (X) + 256) >> 16
const GLint s = CHAN_MAX - t;
const GLint r = DIV255(rgba[i][RCOMP] * t + dest[i][RCOMP] * s);
const GLint g = DIV255(rgba[i][GCOMP] * t + dest[i][GCOMP] * s);
const GLint b = DIV255(rgba[i][BCOMP] * t + dest[i][BCOMP] * s);
const GLint a = DIV255(rgba[i][ACOMP] * t + dest[i][ACOMP] * s);
#undef DIV255
#endif
ASSERT(r <= CHAN_MAX);
ASSERT(g <= CHAN_MAX);
ASSERT(b <= CHAN_MAX);
@ -770,22 +790,22 @@ blend_general( GLcontext *ctx, GLuint n, const GLubyte mask[],
/* compute blended color */
if (ctx->Color.BlendEquation==GL_FUNC_ADD_EXT) {
r = Rs * sR + Rd * dR;
g = Gs * sG + Gd * dG;
b = Bs * sB + Bd * dB;
a = As * sA + Ad * dA;
r = Rs * sR + Rd * dR + 0.5F;
g = Gs * sG + Gd * dG + 0.5F;
b = Bs * sB + Bd * dB + 0.5F;
a = As * sA + Ad * dA + 0.5F;
}
else if (ctx->Color.BlendEquation==GL_FUNC_SUBTRACT_EXT) {
r = Rs * sR - Rd * dR;
g = Gs * sG - Gd * dG;
b = Bs * sB - Bd * dB;
a = As * sA - Ad * dA;
r = Rs * sR - Rd * dR + 0.5F;
g = Gs * sG - Gd * dG + 0.5F;
b = Bs * sB - Bd * dB + 0.5F;
a = As * sA - Ad * dA + 0.5F;
}
else if (ctx->Color.BlendEquation==GL_FUNC_REVERSE_SUBTRACT_EXT) {
r = Rd * dR - Rs * sR;
g = Gd * dG - Gs * sG;
b = Bd * dB - Bs * sB;
a = Ad * dA - As * sA;
r = Rd * dR - Rs * sR + 0.5F;
g = Gd * dG - Gs * sG + 0.5F;
b = Bd * dB - Bs * sB + 0.5F;
a = Ad * dA - As * sA + 0.5F;
}
else {
/* should never get here */