diff options
Diffstat (limited to 'mesalib/src/mesa/swrast/s_alpha.c')
| -rw-r--r-- | mesalib/src/mesa/swrast/s_alpha.c | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/mesalib/src/mesa/swrast/s_alpha.c b/mesalib/src/mesa/swrast/s_alpha.c new file mode 100644 index 000000000..5761bb00b --- /dev/null +++ b/mesalib/src/mesa/swrast/s_alpha.c @@ -0,0 +1,160 @@ +/* + * Mesa 3-D graphics library + * Version: 6.5.2 + * + * Copyright (C) 1999-2006 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 "main/glheader.h" +#include "main/context.h" +#include "main/colormac.h" +#include "main/macros.h" + +#include "s_alpha.h" +#include "s_context.h" + + +#define ALPHA_TEST(ALPHA, LOOP_CODE) \ +do { \ + switch (ctx->Color.AlphaFunc) { \ + case GL_LESS: \ + for (i = 0; i < n; i++) { \ + mask[i] &= (ALPHA < ref); \ + LOOP_CODE; \ + } \ + break; \ + case GL_LEQUAL: \ + for (i = 0; i < n; i++) { \ + mask[i] &= (ALPHA <= ref); \ + LOOP_CODE; \ + } \ + break; \ + case GL_GEQUAL: \ + for (i = 0; i < n; i++) { \ + mask[i] &= (ALPHA >= ref); \ + LOOP_CODE; \ + } \ + break; \ + case GL_GREATER: \ + for (i = 0; i < n; i++) { \ + mask[i] &= (ALPHA > ref); \ + LOOP_CODE; \ + } \ + break; \ + case GL_NOTEQUAL: \ + for (i = 0; i < n; i++) { \ + mask[i] &= (ALPHA != ref); \ + LOOP_CODE; \ + } \ + break; \ + case GL_EQUAL: \ + for (i = 0; i < n; i++) { \ + mask[i] &= (ALPHA == ref); \ + LOOP_CODE; \ + } \ + break; \ + default: \ + _mesa_problem(ctx, "Invalid alpha test in _swrast_alpha_test" ); \ + return 0; \ + } \ +} while (0) + + + +/** + * Perform the alpha test for an array of pixels. + * For pixels that fail the test, mask[i] will be set to 0. + * \return 0 if all pixels in the span failed the alpha test, + * 1 if one or more pixels passed the alpha test. + */ +GLint +_swrast_alpha_test(const GLcontext *ctx, SWspan *span) +{ + const GLuint n = span->end; + GLubyte *mask = span->array->mask; + GLuint i; + + if (ctx->Color.AlphaFunc == GL_ALWAYS) { + /* do nothing */ + return 1; + } + else if (ctx->Color.AlphaFunc == GL_NEVER) { + /* All pixels failed - caller should check for this return value and + * act accordingly. + */ + span->writeAll = GL_FALSE; + return 0; + } + + if (span->arrayMask & SPAN_RGBA) { + /* Use array's alpha values */ + if (span->array->ChanType == GL_UNSIGNED_BYTE) { + GLubyte (*rgba)[4] = span->array->rgba8; + GLubyte ref; + CLAMPED_FLOAT_TO_UBYTE(ref, ctx->Color.AlphaRef); + ALPHA_TEST(rgba[i][ACOMP], ;); + } + else if (span->array->ChanType == GL_UNSIGNED_SHORT) { + GLushort (*rgba)[4] = span->array->rgba16; + GLushort ref; + CLAMPED_FLOAT_TO_USHORT(ref, ctx->Color.AlphaRef); + ALPHA_TEST(rgba[i][ACOMP], ;); + } + else { + GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0]; + const GLfloat ref = ctx->Color.AlphaRef; + ALPHA_TEST(rgba[i][ACOMP], ;); + } + } + else { + /* Interpolate alpha values */ + ASSERT(span->interpMask & SPAN_RGBA); + if (span->array->ChanType == GL_UNSIGNED_BYTE) { + const GLfixed alphaStep = span->alphaStep; + GLfixed alpha = span->alpha; + GLubyte ref; + CLAMPED_FLOAT_TO_UBYTE(ref, ctx->Color.AlphaRef); + ALPHA_TEST(FixedToInt(alpha), alpha += alphaStep); + } + else if (span->array->ChanType == GL_UNSIGNED_SHORT) { + const GLfixed alphaStep = span->alphaStep; + GLfixed alpha = span->alpha; + GLushort ref; + CLAMPED_FLOAT_TO_USHORT(ref, ctx->Color.AlphaRef); + ALPHA_TEST(FixedToInt(alpha), alpha += alphaStep); + } + else { + const GLfloat alphaStep = span->alphaStep; + GLfloat alpha = span->alpha; + const GLfloat ref = ctx->Color.AlphaRef; + ALPHA_TEST(alpha, alpha += alphaStep); + } + } + + span->writeAll = GL_FALSE; + + /* XXX examine mask[] values? */ + return 1; +} |