| 1 | /* $Id: alpha.c,v 1.3 2000-05-23 20:40:20 jeroen Exp $ */
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| 2 |
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| 3 | /*
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| 4 | * Mesa 3-D graphics library
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| 5 | * Version: 3.3
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| 6 | *
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| 7 | * Copyright (C) 1999 Brian Paul All Rights Reserved.
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| 8 | *
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| 9 | * Permission is hereby granted, free of charge, to any person obtaining a
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| 10 | * copy of this software and associated documentation files (the "Software"),
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| 11 | * to deal in the Software without restriction, including without limitation
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| 12 | * the rights to use, copy, modify, merge, publish, distribute, sublicense,
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| 13 | * and/or sell copies of the Software, and to permit persons to whom the
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| 14 | * Software is furnished to do so, subject to the following conditions:
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| 15 | *
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| 16 | * The above copyright notice and this permission notice shall be included
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| 17 | * in all copies or substantial portions of the Software.
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| 18 | *
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| 19 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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| 20 | * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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| 21 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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| 22 | * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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| 23 | * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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| 24 | * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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| 25 | */
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| 26 | /* $XFree86: xc/lib/GL/mesa/src/alpha.c,v 1.2 1999/04/04 00:20:18 dawes Exp $ */
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| 27 |
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| 28 |
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| 29 |
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| 30 | #ifdef PC_HEADER
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| 31 | #include "all.h"
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| 32 | #else
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| 33 | #include "glheader.h"
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| 34 | #include "alpha.h"
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| 35 | #include "types.h"
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| 36 | #include "context.h"
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| 37 | #include "macros.h"
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| 38 | #include "mmath.h"
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| 39 | #endif
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| 40 |
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| 41 |
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| 42 |
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| 43 | void
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| 44 | _mesa_AlphaFunc( GLenum func, GLclampf ref )
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| 45 | {
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| 46 | GET_CURRENT_CONTEXT(ctx);
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| 47 | ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx, "glAlphaFunc");
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| 48 |
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| 49 | switch (func) {
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| 50 | case GL_NEVER:
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| 51 | case GL_LESS:
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| 52 | case GL_EQUAL:
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| 53 | case GL_LEQUAL:
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| 54 | case GL_GREATER:
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| 55 | case GL_NOTEQUAL:
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| 56 | case GL_GEQUAL:
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| 57 | case GL_ALWAYS:
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| 58 | ctx->Color.AlphaFunc = func;
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| 59 | if (ref <= 0.0)
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| 60 | ctx->Color.AlphaRef = (GLubyte) 0;
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| 61 | else if (ref >= 1.0)
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| 62 | ctx->Color.AlphaRef = (GLubyte) 255;
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| 63 | else
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| 64 | CLAMPED_FLOAT_COLOR_TO_UBYTE_COLOR(ctx->Color.AlphaRef, ref);
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| 65 | if (ctx->Driver.AlphaFunc) {
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| 66 | (*ctx->Driver.AlphaFunc)(ctx, func, ctx->Color.AlphaRef);
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| 67 | }
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| 68 | break;
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| 69 | default:
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| 70 | gl_error( ctx, GL_INVALID_ENUM, "glAlphaFunc(func)" );
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| 71 | break;
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| 72 | }
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| 73 | }
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| 74 |
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| 75 |
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| 76 |
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| 77 |
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| 78 | /*
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| 79 | * Apply the alpha test to a span of pixels.
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| 80 | * In: rgba - array of pixels
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| 81 | * In/Out: mask - current pixel mask. Pixels which fail the alpha test
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| 82 | * will set the corresponding mask flag to 0.
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| 83 | * Return: 0 = all pixels in the span failed the alpha test.
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| 84 | * 1 = one or more pixels passed the alpha test.
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| 85 | */
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| 86 | GLint
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| 87 | _mesa_alpha_test( const GLcontext* ctx,
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| 88 | GLuint n, CONST GLubyte rgba[][4], GLubyte mask[] )
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| 89 | {
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| 90 | GLuint i;
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| 91 | GLubyte ref = ctx->Color.AlphaRef;
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| 92 |
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| 93 | /* switch cases ordered from most frequent to less frequent */
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| 94 | switch (ctx->Color.AlphaFunc) {
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| 95 | case GL_LESS:
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| 96 | for (i=0;i<n;i++) {
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| 97 | mask[i] &= (rgba[i][ACOMP] < ref);
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| 98 | }
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| 99 | return 1;
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| 100 | case GL_LEQUAL:
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| 101 | for (i=0;i<n;i++) {
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| 102 | mask[i] &= (rgba[i][ACOMP] <= ref);
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| 103 | }
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| 104 | return 1;
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| 105 | case GL_GEQUAL:
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| 106 | for (i=0;i<n;i++) {
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| 107 | mask[i] &= (rgba[i][ACOMP] >= ref);
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| 108 | }
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| 109 | return 1;
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| 110 | case GL_GREATER:
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| 111 | for (i=0;i<n;i++) {
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| 112 | mask[i] &= (rgba[i][ACOMP] > ref);
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| 113 | }
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| 114 | return 1;
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| 115 | case GL_NOTEQUAL:
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| 116 | for (i=0;i<n;i++) {
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| 117 | mask[i] &= (rgba[i][ACOMP] != ref);
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| 118 | }
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| 119 | return 1;
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| 120 | case GL_EQUAL:
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| 121 | for (i=0;i<n;i++) {
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| 122 | mask[i] &= (rgba[i][ACOMP] == ref);
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| 123 | }
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| 124 | return 1;
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| 125 | case GL_ALWAYS:
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| 126 | /* do nothing */
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| 127 | return 1;
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| 128 | case GL_NEVER:
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| 129 | /* caller should check for zero! */
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| 130 | return 0;
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| 131 | default:
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| 132 | gl_problem( ctx, "Invalid alpha test in gl_alpha_test" );
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| 133 | return 0;
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| 134 | }
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| 135 | /* Never get here */
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| 136 | /*return 1;*/
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| 137 | }
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