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/* $Id: fog.c,v 1.8 1997/06/20 04:14:47 brianp Exp $ */
/*
* Mesa 3-D graphics library
* Version: 2.3
* Copyright (C) 1995-1996 Brian Paul
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* $Log: fog.c,v $
* Revision 1.8 1997/06/20 04:14:47 brianp
* changed color components from GLfixed to GLubyte
*
* Revision 1.7 1997/05/28 03:24:54 brianp
* added precompiled header (PCH) support
*
* Revision 1.6 1997/05/22 03:03:47 brianp
* don't apply fog to alpha values
*
* Revision 1.5 1997/04/20 20:28:49 brianp
* replaced abort() with gl_problem()
*
* Revision 1.4 1996/11/04 02:30:15 brianp
* optimized gl_fog_color_pixels() and gl_fog_index_pixels()
*
* Revision 1.3 1996/09/27 01:26:52 brianp
* added missing default cases to switches
*
* Revision 1.2 1996/09/15 14:17:30 brianp
* now use GLframebuffer and GLvisual
*
* Revision 1.1 1996/09/13 01:38:16 brianp
* Initial revision
*
*/
#ifdef PCH
#include "all.h"
#else
#include <math.h>
#include <stdlib.h>
#include "context.h"
#include "fog.h"
#include "dlist.h"
#include "macros.h"
#include "types.h"
#endif
void gl_Fogfv( GLcontext *ctx, GLenum pname, const GLfloat *params )
{
GLenum m;
switch (pname) {
case GL_FOG_MODE:
m = (GLenum) (GLint) *params;
if (m==GL_LINEAR || m==GL_EXP || m==GL_EXP2) {
ctx->Fog.Mode = m;
}
else {
gl_error( ctx, GL_INVALID_ENUM, "glFog" );
}
break;
case GL_FOG_DENSITY:
if (*params<0.0) {
gl_error( ctx, GL_INVALID_VALUE, "glFog" );
}
else {
ctx->Fog.Density = *params;
}
break;
case GL_FOG_START:
#ifndef GL_VERSION_1_1
if (*params<0.0F) {
gl_error( ctx, GL_INVALID_VALUE, "glFog(GL_FOG_START)" );
return;
}
#endif
ctx->Fog.Start = *params;
break;
case GL_FOG_END:
#ifndef GL_VERSION_1_1
if (*params<0.0F) {
gl_error( ctx, GL_INVALID_VALUE, "glFog(GL_FOG_END)" );
return;
}
#endif
ctx->Fog.End = *params;
break;
case GL_FOG_INDEX:
ctx->Fog.Index = *params;
break;
case GL_FOG_COLOR:
ctx->Fog.Color[0] = params[0];
ctx->Fog.Color[1] = params[1];
ctx->Fog.Color[2] = params[2];
ctx->Fog.Color[3] = params[3];
break;
default:
gl_error( ctx, GL_INVALID_ENUM, "glFog" );
}
}
/*
* Compute the fogged color for an array of vertices.
* Input: n - number of vertices
* v - array of vertices
* color - the original vertex colors
* Output: color - the fogged colors
*/
void gl_fog_color_vertices( GLcontext *ctx,
GLuint n, GLfloat v[][4], GLubyte color[][4] )
{
GLuint i;
GLfloat d;
GLfloat fogr = ctx->Fog.Color[0] * ctx->Visual->RedScale;
GLfloat fogg = ctx->Fog.Color[1] * ctx->Visual->GreenScale;
GLfloat fogb = ctx->Fog.Color[2] * ctx->Visual->BlueScale;
GLfloat end = ctx->Fog.End;
switch (ctx->Fog.Mode) {
case GL_LINEAR:
d = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
for (i=0;i<n;i++) {
GLfloat f = (end - ABSF(v[i][2])) * d;
f = CLAMP( f, 0.0F, 1.0F );
color[i][0] = f * color[i][0] + (1.0F-f) * fogr;
color[i][1] = f * color[i][1] + (1.0F-f) * fogg;
color[i][2] = f * color[i][2] + (1.0F-f) * fogb;
}
break;
case GL_EXP:
d = -ctx->Fog.Density;
for (i=0;i<n;i++) {
GLfloat f = exp( d * ABSF(v[i][2]) );
f = CLAMP( f, 0.0F, 1.0F );
color[i][0] = f * color[i][0] + (1.0F-f) * fogr;
color[i][1] = f * color[i][1] + (1.0F-f) * fogg;
color[i][2] = f * color[i][2] + (1.0F-f) * fogb;
}
break;
case GL_EXP2:
d = -(ctx->Fog.Density*ctx->Fog.Density);
for (i=0;i<n;i++) {
GLfloat z = ABSF(v[i][2]);
GLfloat f = exp( d * z*z );
f = CLAMP( f, 0.0F, 1.0F );
color[i][0] = f * color[i][0] + (1.0F-f) * fogr;
color[i][1] = f * color[i][1] + (1.0F-f) * fogg;
color[i][2] = f * color[i][2] + (1.0F-f) * fogb;
}
break;
default:
gl_problem(ctx, "Bad fog mode in gl_fog_color_vertices");
return;
}
}
/*
* Compute the fogged color indexes for an array of vertices.
* Input: n - number of vertices
* v - array of vertices
* In/Out: indx - array of vertex color indexes
*/
void gl_fog_index_vertices( GLcontext *ctx,
GLuint n, GLfloat v[][4], GLuint indx[] )
{
/* NOTE: the extensive use of casts generates better/faster code for MIPS */
switch (ctx->Fog.Mode) {
case GL_LINEAR:
{
GLfloat d = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
GLfloat fogindex = ctx->Fog.Index;
GLfloat fogend = ctx->Fog.End;
GLuint i;
for (i=0;i<n;i++) {
GLfloat f = (fogend - ABSF(v[i][2])) * d;
f = CLAMP( f, 0.0F, 1.0F );
indx[i] = (GLint)
((GLfloat) (GLint) indx[i] + (1.0F-f) * fogindex);
}
}
break;
case GL_EXP:
{
GLfloat d = -ctx->Fog.Density;
GLfloat fogindex = ctx->Fog.Index;
GLuint i;
for (i=0;i<n;i++) {
GLfloat f = exp( d * ABSF(v[i][2]) );
f = CLAMP( f, 0.0F, 1.0F );
indx[i] = (GLint)
((GLfloat) (GLint) indx[i] + (1.0F-f) * fogindex);
}
}
break;
case GL_EXP2:
{
GLfloat d = -(ctx->Fog.Density*ctx->Fog.Density);
GLfloat fogindex = ctx->Fog.Index;
GLuint i;
for (i=0;i<n;i++) {
GLfloat z = ABSF(v[i][2]);
GLfloat f = exp( -d * z*z );
f = CLAMP( f, 0.0F, 1.0F );
indx[i] = (GLint)
((GLfloat) (GLint) indx[i] + (1.0F-f) * fogindex);
}
}
break;
default:
gl_problem(ctx, "Bad fog mode in gl_fog_index_vertices");
return;
}
}
/*
* Apply fog to an array of RGBA pixels.
* Input: n - number of pixels
* z - array of integer depth values
* red, green, blue, alpha - pixel colors
* Output: red, green, blue, alpha - fogged pixel colors
*/
void gl_fog_color_pixels( GLcontext *ctx,
GLuint n, const GLdepth z[], GLubyte red[],
GLubyte green[], GLubyte blue[], GLubyte alpha[] )
{
GLfloat c = ctx->ProjectionMatrix[10];
GLfloat d = ctx->ProjectionMatrix[14];
GLuint i;
GLfloat fog_red = ctx->Fog.Color[0] * ctx->Visual->RedScale;
GLfloat fog_green = ctx->Fog.Color[1] * ctx->Visual->GreenScale;
GLfloat fog_blue = ctx->Fog.Color[2] * ctx->Visual->BlueScale;
GLfloat tz = ctx->Viewport.Tz;
GLfloat szInv = 1.0F / ctx->Viewport.Sz;
switch (ctx->Fog.Mode) {
case GL_LINEAR:
{
GLfloat fogEnd = ctx->Fog.End;
GLfloat fogScale = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = -d / (c+ndcz);
GLfloat f, g;
if (eyez < 0.0) eyez = -eyez;
f = (fogEnd - eyez) * fogScale;
f = CLAMP( f, 0.0F, 1.0F );
g = 1.0F - f;
red[i] = (GLint) (f * (GLfloat) red[i] + g * fog_red);
green[i] = (GLint) (f * (GLfloat) green[i] + g * fog_green);
blue[i] = (GLint) (f * (GLfloat) blue[i] + g * fog_blue);
}
}
break;
case GL_EXP:
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = -d / (c+ndcz);
GLfloat f, g;
if (eyez < 0.0) eyez = -eyez;
f = exp( -ctx->Fog.Density * eyez );
f = CLAMP( f, 0.0F, 1.0F );
g = 1.0F - f;
red[i] = (GLint) (f * (GLfloat) red[i] + g * fog_red);
green[i] = (GLint) (f * (GLfloat) green[i] + g * fog_green);
blue[i] = (GLint) (f * (GLfloat) blue[i] + g * fog_blue);
}
break;
case GL_EXP2:
{
GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = -d / (c+ndcz);
GLfloat f, g;
if (eyez < 0.0) eyez = -eyez;
f = exp( negDensitySquared * eyez*eyez );
f = CLAMP( f, 0.0F, 1.0F );
g = 1.0F - f;
red[i] = (GLint) (f * (GLfloat) red[i] + g * fog_red);
green[i] = (GLint) (f * (GLfloat) green[i] + g * fog_green);
blue[i] = (GLint) (f * (GLfloat) blue[i] + g * fog_blue);
}
}
break;
default:
gl_problem(ctx, "Bad fog mode in gl_fog_color_pixels");
return;
}
}
/*
* Apply fog to an array of color index pixels.
* Input: n - number of pixels
* z - array of integer depth values
* index - pixel color indexes
* Output: index - fogged pixel color indexes
*/
void gl_fog_index_pixels( GLcontext *ctx,
GLuint n, const GLdepth z[], GLuint index[] )
{
GLfloat c = ctx->ProjectionMatrix[10];
GLfloat d = ctx->ProjectionMatrix[14];
GLuint i;
GLfloat tz = ctx->Viewport.Tz;
GLfloat szInv = 1.0F / ctx->Viewport.Sz;
switch (ctx->Fog.Mode) {
case GL_LINEAR:
{
GLfloat fogEnd = ctx->Fog.End;
GLfloat fogScale = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = -d / (c+ndcz);
GLfloat f;
if (eyez < 0.0) eyez = -eyez;
f = (fogEnd - eyez) * fogScale;
f = CLAMP( f, 0.0F, 1.0F );
index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
}
}
break;
case GL_EXP:
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = -d / (c+ndcz);
GLfloat f;
if (eyez < 0.0) eyez = -eyez;
f = exp( -ctx->Fog.Density * eyez );
f = CLAMP( f, 0.0F, 1.0F );
index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
}
break;
case GL_EXP2:
{
GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
for (i=0;i<n;i++) {
GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
GLfloat eyez = -d / (c+ndcz);
GLfloat f;
if (eyez < 0.0) eyez = -eyez;
f = exp( negDensitySquared * eyez*eyez );
f = CLAMP( f, 0.0F, 1.0F );
index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
}
}
break;
default:
gl_problem(ctx, "Bad fog mode in gl_fog_index_pixels");
return;
}
}
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