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390 lines
12 KiB
C
390 lines
12 KiB
C
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/* $Id: fog.c,v 1.9 1997/07/24 01:25:01 brianp Exp $ */
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/*
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* Mesa 3-D graphics library
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* Version: 2.4
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* Copyright (C) 1995-1996 Brian Paul
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free
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* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/*
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* $Log: fog.c,v $
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* Revision 1.9 1997/07/24 01:25:01 brianp
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* changed precompiled header symbol from PCH to PC_HEADER
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*
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* Revision 1.8 1997/06/20 04:14:47 brianp
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* changed color components from GLfixed to GLubyte
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*
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* Revision 1.7 1997/05/28 03:24:54 brianp
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* added precompiled header (PCH) support
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*
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* Revision 1.6 1997/05/22 03:03:47 brianp
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* don't apply fog to alpha values
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*
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* Revision 1.5 1997/04/20 20:28:49 brianp
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* replaced abort() with gl_problem()
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*
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* Revision 1.4 1996/11/04 02:30:15 brianp
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* optimized gl_fog_color_pixels() and gl_fog_index_pixels()
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*
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* Revision 1.3 1996/09/27 01:26:52 brianp
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* added missing default cases to switches
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*
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* Revision 1.2 1996/09/15 14:17:30 brianp
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* now use GLframebuffer and GLvisual
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*
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* Revision 1.1 1996/09/13 01:38:16 brianp
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* Initial revision
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*
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*/
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#ifdef PC_HEADER
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#include "all.h"
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#else
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#include <math.h>
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#include <stdlib.h>
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#include "context.h"
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#include "fog.h"
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#include "dlist.h"
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#include "macros.h"
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#include "types.h"
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#endif
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void gl_Fogfv( GLcontext *ctx, GLenum pname, const GLfloat *params )
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{
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GLenum m;
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switch (pname) {
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case GL_FOG_MODE:
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m = (GLenum) (GLint) *params;
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if (m==GL_LINEAR || m==GL_EXP || m==GL_EXP2) {
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ctx->Fog.Mode = m;
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}
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else {
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gl_error( ctx, GL_INVALID_ENUM, "glFog" );
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}
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break;
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case GL_FOG_DENSITY:
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if (*params<0.0) {
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gl_error( ctx, GL_INVALID_VALUE, "glFog" );
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}
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else {
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ctx->Fog.Density = *params;
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}
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break;
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case GL_FOG_START:
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#ifndef GL_VERSION_1_1
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if (*params<0.0F) {
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gl_error( ctx, GL_INVALID_VALUE, "glFog(GL_FOG_START)" );
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return;
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}
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#endif
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ctx->Fog.Start = *params;
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break;
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case GL_FOG_END:
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#ifndef GL_VERSION_1_1
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if (*params<0.0F) {
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gl_error( ctx, GL_INVALID_VALUE, "glFog(GL_FOG_END)" );
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return;
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}
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#endif
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ctx->Fog.End = *params;
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break;
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case GL_FOG_INDEX:
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ctx->Fog.Index = *params;
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break;
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case GL_FOG_COLOR:
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ctx->Fog.Color[0] = params[0];
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ctx->Fog.Color[1] = params[1];
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ctx->Fog.Color[2] = params[2];
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ctx->Fog.Color[3] = params[3];
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break;
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default:
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gl_error( ctx, GL_INVALID_ENUM, "glFog" );
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}
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}
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/*
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* Compute the fogged color for an array of vertices.
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* Input: n - number of vertices
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* v - array of vertices
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* color - the original vertex colors
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* Output: color - the fogged colors
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*/
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void gl_fog_color_vertices( GLcontext *ctx,
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GLuint n, GLfloat v[][4], GLubyte color[][4] )
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{
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GLuint i;
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GLfloat d;
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GLfloat fogr = ctx->Fog.Color[0] * ctx->Visual->RedScale;
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GLfloat fogg = ctx->Fog.Color[1] * ctx->Visual->GreenScale;
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GLfloat fogb = ctx->Fog.Color[2] * ctx->Visual->BlueScale;
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GLfloat end = ctx->Fog.End;
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switch (ctx->Fog.Mode) {
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case GL_LINEAR:
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d = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
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for (i=0;i<n;i++) {
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GLfloat f = (end - ABSF(v[i][2])) * d;
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f = CLAMP( f, 0.0F, 1.0F );
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color[i][0] = f * color[i][0] + (1.0F-f) * fogr;
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color[i][1] = f * color[i][1] + (1.0F-f) * fogg;
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color[i][2] = f * color[i][2] + (1.0F-f) * fogb;
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}
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break;
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case GL_EXP:
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d = -ctx->Fog.Density;
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for (i=0;i<n;i++) {
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GLfloat f = exp( d * ABSF(v[i][2]) );
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f = CLAMP( f, 0.0F, 1.0F );
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color[i][0] = f * color[i][0] + (1.0F-f) * fogr;
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color[i][1] = f * color[i][1] + (1.0F-f) * fogg;
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color[i][2] = f * color[i][2] + (1.0F-f) * fogb;
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}
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break;
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case GL_EXP2:
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d = -(ctx->Fog.Density*ctx->Fog.Density);
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for (i=0;i<n;i++) {
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GLfloat z = ABSF(v[i][2]);
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GLfloat f = exp( d * z*z );
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f = CLAMP( f, 0.0F, 1.0F );
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color[i][0] = f * color[i][0] + (1.0F-f) * fogr;
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color[i][1] = f * color[i][1] + (1.0F-f) * fogg;
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color[i][2] = f * color[i][2] + (1.0F-f) * fogb;
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}
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break;
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default:
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gl_problem(ctx, "Bad fog mode in gl_fog_color_vertices");
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return;
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}
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}
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/*
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* Compute the fogged color indexes for an array of vertices.
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* Input: n - number of vertices
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* v - array of vertices
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* In/Out: indx - array of vertex color indexes
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*/
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void gl_fog_index_vertices( GLcontext *ctx,
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GLuint n, GLfloat v[][4], GLuint indx[] )
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{
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/* NOTE: the extensive use of casts generates better/faster code for MIPS */
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switch (ctx->Fog.Mode) {
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case GL_LINEAR:
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{
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GLfloat d = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
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GLfloat fogindex = ctx->Fog.Index;
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GLfloat fogend = ctx->Fog.End;
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GLuint i;
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for (i=0;i<n;i++) {
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GLfloat f = (fogend - ABSF(v[i][2])) * d;
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f = CLAMP( f, 0.0F, 1.0F );
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indx[i] = (GLint)
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((GLfloat) (GLint) indx[i] + (1.0F-f) * fogindex);
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}
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}
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break;
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case GL_EXP:
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{
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GLfloat d = -ctx->Fog.Density;
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GLfloat fogindex = ctx->Fog.Index;
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GLuint i;
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for (i=0;i<n;i++) {
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GLfloat f = exp( d * ABSF(v[i][2]) );
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f = CLAMP( f, 0.0F, 1.0F );
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indx[i] = (GLint)
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((GLfloat) (GLint) indx[i] + (1.0F-f) * fogindex);
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}
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}
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break;
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case GL_EXP2:
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{
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GLfloat d = -(ctx->Fog.Density*ctx->Fog.Density);
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GLfloat fogindex = ctx->Fog.Index;
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GLuint i;
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for (i=0;i<n;i++) {
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GLfloat z = ABSF(v[i][2]);
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GLfloat f = exp( -d * z*z );
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f = CLAMP( f, 0.0F, 1.0F );
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indx[i] = (GLint)
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((GLfloat) (GLint) indx[i] + (1.0F-f) * fogindex);
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}
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}
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break;
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default:
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gl_problem(ctx, "Bad fog mode in gl_fog_index_vertices");
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return;
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}
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}
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/*
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* Apply fog to an array of RGBA pixels.
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* Input: n - number of pixels
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* z - array of integer depth values
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* red, green, blue, alpha - pixel colors
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* Output: red, green, blue, alpha - fogged pixel colors
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*/
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void gl_fog_color_pixels( GLcontext *ctx,
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GLuint n, const GLdepth z[], GLubyte red[],
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GLubyte green[], GLubyte blue[], GLubyte alpha[] )
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{
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GLfloat c = ctx->ProjectionMatrix[10];
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GLfloat d = ctx->ProjectionMatrix[14];
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GLuint i;
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GLfloat fog_red = ctx->Fog.Color[0] * ctx->Visual->RedScale;
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GLfloat fog_green = ctx->Fog.Color[1] * ctx->Visual->GreenScale;
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GLfloat fog_blue = ctx->Fog.Color[2] * ctx->Visual->BlueScale;
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GLfloat tz = ctx->Viewport.Tz;
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GLfloat szInv = 1.0F / ctx->Viewport.Sz;
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switch (ctx->Fog.Mode) {
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case GL_LINEAR:
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{
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GLfloat fogEnd = ctx->Fog.End;
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GLfloat fogScale = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
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for (i=0;i<n;i++) {
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GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
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GLfloat eyez = -d / (c+ndcz);
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GLfloat f, g;
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if (eyez < 0.0) eyez = -eyez;
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f = (fogEnd - eyez) * fogScale;
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f = CLAMP( f, 0.0F, 1.0F );
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g = 1.0F - f;
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red[i] = (GLint) (f * (GLfloat) red[i] + g * fog_red);
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green[i] = (GLint) (f * (GLfloat) green[i] + g * fog_green);
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blue[i] = (GLint) (f * (GLfloat) blue[i] + g * fog_blue);
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}
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}
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break;
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case GL_EXP:
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for (i=0;i<n;i++) {
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GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
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GLfloat eyez = -d / (c+ndcz);
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GLfloat f, g;
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if (eyez < 0.0) eyez = -eyez;
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f = exp( -ctx->Fog.Density * eyez );
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f = CLAMP( f, 0.0F, 1.0F );
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g = 1.0F - f;
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red[i] = (GLint) (f * (GLfloat) red[i] + g * fog_red);
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green[i] = (GLint) (f * (GLfloat) green[i] + g * fog_green);
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blue[i] = (GLint) (f * (GLfloat) blue[i] + g * fog_blue);
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}
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break;
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case GL_EXP2:
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{
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GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
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for (i=0;i<n;i++) {
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GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
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GLfloat eyez = -d / (c+ndcz);
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GLfloat f, g;
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if (eyez < 0.0) eyez = -eyez;
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f = exp( negDensitySquared * eyez*eyez );
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f = CLAMP( f, 0.0F, 1.0F );
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g = 1.0F - f;
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red[i] = (GLint) (f * (GLfloat) red[i] + g * fog_red);
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green[i] = (GLint) (f * (GLfloat) green[i] + g * fog_green);
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blue[i] = (GLint) (f * (GLfloat) blue[i] + g * fog_blue);
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}
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}
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break;
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default:
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gl_problem(ctx, "Bad fog mode in gl_fog_color_pixels");
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return;
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}
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}
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/*
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* Apply fog to an array of color index pixels.
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* Input: n - number of pixels
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* z - array of integer depth values
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* index - pixel color indexes
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* Output: index - fogged pixel color indexes
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*/
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void gl_fog_index_pixels( GLcontext *ctx,
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GLuint n, const GLdepth z[], GLuint index[] )
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{
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GLfloat c = ctx->ProjectionMatrix[10];
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GLfloat d = ctx->ProjectionMatrix[14];
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GLuint i;
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GLfloat tz = ctx->Viewport.Tz;
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GLfloat szInv = 1.0F / ctx->Viewport.Sz;
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switch (ctx->Fog.Mode) {
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case GL_LINEAR:
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{
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GLfloat fogEnd = ctx->Fog.End;
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GLfloat fogScale = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
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for (i=0;i<n;i++) {
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GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
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GLfloat eyez = -d / (c+ndcz);
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GLfloat f;
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if (eyez < 0.0) eyez = -eyez;
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f = (fogEnd - eyez) * fogScale;
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f = CLAMP( f, 0.0F, 1.0F );
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index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
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}
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}
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break;
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case GL_EXP:
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for (i=0;i<n;i++) {
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GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
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GLfloat eyez = -d / (c+ndcz);
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GLfloat f;
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if (eyez < 0.0) eyez = -eyez;
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f = exp( -ctx->Fog.Density * eyez );
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f = CLAMP( f, 0.0F, 1.0F );
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index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
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}
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break;
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case GL_EXP2:
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{
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GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
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for (i=0;i<n;i++) {
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GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
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GLfloat eyez = -d / (c+ndcz);
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GLfloat f;
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if (eyez < 0.0) eyez = -eyez;
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f = exp( negDensitySquared * eyez*eyez );
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f = CLAMP( f, 0.0F, 1.0F );
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index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
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}
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}
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break;
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default:
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gl_problem(ctx, "Bad fog mode in gl_fog_index_pixels");
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return;
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}
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}
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