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Diffstat (limited to 'src/mesa/swrast/s_alpha.c')
| -rw-r--r-- | src/mesa/swrast/s_alpha.c | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/src/mesa/swrast/s_alpha.c b/src/mesa/swrast/s_alpha.c new file mode 100644 index 00000000000..55c1e6a58f8 --- /dev/null +++ b/src/mesa/swrast/s_alpha.c @@ -0,0 +1,224 @@ + +/* + * Mesa 3-D graphics library + * Version: 4.1 + * + * Copyright (C) 1999-2002 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"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included + * in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS + * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN + * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + */ + +/** + * \file swrast/s_alpha.c + * \brief Functions to apply alpha test. + */ + +#include "glheader.h" +#include "context.h" +#include "colormac.h" +#include "macros.h" + +#include "s_alpha.h" +#include "s_context.h" + + +/** + * \fn GLint _swrast_alpha_test( const GLcontext *ctx, struct sw_span *span ) + * \brief Apply the alpha test to a span of pixels. + * \return + * - "0" = all pixels in the span failed the alpha test. + * - "1" = one or more pixels passed the alpha test. + */ +GLint +_swrast_alpha_test( const GLcontext *ctx, struct sw_span *span ) +{ + const GLchan (*rgba)[4] = (const GLchan (*)[4]) span->array->rgba; + GLchan ref; + const GLuint n = span->end; + GLubyte *mask = span->array->mask; + GLuint i; + + CLAMPED_FLOAT_TO_CHAN(ref, ctx->Color.AlphaRef); + + if (span->arrayMask & SPAN_RGBA) { + /* Use the array values */ + switch (ctx->Color.AlphaFunc) { + case GL_LESS: + for (i = 0; i < n; i++) + mask[i] &= (rgba[i][ACOMP] < ref); + break; + case GL_LEQUAL: + for (i = 0; i < n; i++) + mask[i] &= (rgba[i][ACOMP] <= ref); + break; + case GL_GEQUAL: + for (i = 0; i < n; i++) + mask[i] &= (rgba[i][ACOMP] >= ref); + break; + case GL_GREATER: + for (i = 0; i < n; i++) + mask[i] &= (rgba[i][ACOMP] > ref); + break; + case GL_NOTEQUAL: + for (i = 0; i < n; i++) + mask[i] &= (rgba[i][ACOMP] != ref); + break; + case GL_EQUAL: + for (i = 0; i < n; i++) + mask[i] &= (rgba[i][ACOMP] == ref); + break; + case GL_ALWAYS: + /* do nothing */ + return 1; + case GL_NEVER: + /* caller should check for zero! */ + span->writeAll = GL_FALSE; + return 0; + default: + _mesa_problem( ctx, "Invalid alpha test in _swrast_alpha_test" ); + return 0; + } + } + else { + /* Use the interpolation values */ +#if CHAN_TYPE == GL_FLOAT + const GLfloat alphaStep = span->alphaStep; + GLfloat alpha = span->alpha; + ASSERT(span->interpMask & SPAN_RGBA); + switch (ctx->Color.AlphaFunc) { + case GL_LESS: + for (i = 0; i < n; i++) { + mask[i] &= (alpha < ref); + alpha += alphaStep; + } + break; + case GL_LEQUAL: + for (i = 0; i < n; i++) { + mask[i] &= (alpha <= ref); + alpha += alphaStep; + } + break; + case GL_GEQUAL: + for (i = 0; i < n; i++) { + mask[i] &= (alpha >= ref); + alpha += alphaStep; + } + break; + case GL_GREATER: + for (i = 0; i < n; i++) { + mask[i] &= (alpha > ref); + alpha += alphaStep; + } + break; + case GL_NOTEQUAL: + for (i = 0; i < n; i++) { + mask[i] &= (alpha != ref); + alpha += alphaStep; + } + break; + case GL_EQUAL: + for (i = 0; i < n; i++) { + mask[i] &= (alpha == ref); + alpha += alphaStep; + } + break; + case GL_ALWAYS: + /* do nothing */ + return 1; + case GL_NEVER: + /* caller should check for zero! */ + span->writeAll = GL_FALSE; + return 0; + default: + _mesa_problem( ctx, "Invalid alpha test in gl_alpha_test" ); + return 0; + } +#else + /* 8 or 16-bit channel interpolation */ + const GLfixed alphaStep = span->alphaStep; + GLfixed alpha = span->alpha; + ASSERT(span->interpMask & SPAN_RGBA); + switch (ctx->Color.AlphaFunc) { + case GL_LESS: + for (i = 0; i < n; i++) { + mask[i] &= (FixedToChan(alpha) < ref); + alpha += alphaStep; + } + break; + case GL_LEQUAL: + for (i = 0; i < n; i++) { + mask[i] &= (FixedToChan(alpha) <= ref); + alpha += alphaStep; + } + break; + case GL_GEQUAL: + for (i = 0; i < n; i++) { + mask[i] &= (FixedToChan(alpha) >= ref); + alpha += alphaStep; + } + break; + case GL_GREATER: + for (i = 0; i < n; i++) { + mask[i] &= (FixedToChan(alpha) > ref); + alpha += alphaStep; + } + break; + case GL_NOTEQUAL: + for (i = 0; i < n; i++) { + mask[i] &= (FixedToChan(alpha) != ref); + alpha += alphaStep; + } + break; + case GL_EQUAL: + for (i = 0; i < n; i++) { + mask[i] &= (FixedToChan(alpha) == ref); + alpha += alphaStep; + } + break; + case GL_ALWAYS: + /* do nothing */ + return 1; + case GL_NEVER: + /* caller should check for zero! */ + span->writeAll = GL_FALSE; + return 0; + default: + _mesa_problem( ctx, "Invalid alpha test in gl_alpha_test" ); + return 0; + } +#endif /* CHAN_TYPE */ + } + +#if 0 + /* XXXX This causes conformance failures!!!! */ + while ((span->start <= span->end) && + (mask[span->start] == 0)) + span->start ++; + + while ((span->end >= span->start) && + (mask[span->end] == 0)) + span->end --; +#endif + + span->writeAll = GL_FALSE; + + if (span->start >= span->end) + return 0; + else + return 1; +} |