fog.h File Reference

#include "types.h"

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Go to the source code of this file.

Functions
void	gl_Fogfv (GLcontext *ctx, GLenum pname, const GLfloat *params)
void	gl_fog_color_vertices (GLcontext *ctx, GLuint n, GLfloat v[][4], GLubyte color[][4])
void	gl_fog_index_vertices (GLcontext *ctx, GLuint n, GLfloat v[][4], GLuint indx[])
void	gl_fog_color_pixels (GLcontext *ctx, GLuint n, const GLdepth z[], GLubyte red[], GLubyte green[], GLubyte blue[], GLubyte alpha[])
void	gl_fog_index_pixels (GLcontext *ctx, GLuint n, const GLdepth z[], GLuint indx[])

Function Documentation

gl_fog_color_pixels()

void gl_fog_color_pixels	(	GLcontext *	ctx,
		GLuint	n,
		const GLdepth	z[],
		GLubyte	red[],
		GLubyte	green[],
		GLubyte	blue[],
		GLubyte	alpha[]
	)

Definition at line 252 of file fog.c.

{
   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;
   }
}

Referenced by gl_flush_pb(), gl_write_color_span(), and gl_write_texture_span().

gl_fog_color_vertices()

void gl_fog_color_vertices	(	GLcontext *	ctx,
		GLuint	n,
		GLfloat	v[][4],
		GLubyte	color[][4]
	)

Definition at line 134 of file fog.c.

{
   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;
   }
}

Referenced by fog_vertices().

gl_fog_index_pixels()

void gl_fog_index_pixels	(	GLcontext *	ctx,
		GLuint	n,
		const GLdepth	z[],
		GLuint	indx[]
	)

Definition at line 333 of file fog.c.

{
   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;
   }
}

Referenced by gl_flush_pb(), gl_write_index_span(), and gl_write_monoindex_span().

gl_fog_index_vertices()

void gl_fog_index_vertices	(	GLcontext *	ctx,
		GLuint	n,
		GLfloat	v[][4],
		GLuint	indx[]
	)

Definition at line 190 of file fog.c.

{
   /* 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;
   }
}

Referenced by fog_vertices().

gl_Fogfv()

void gl_Fogfv	(	GLcontext *	ctx,
		GLenum	pname,
		const GLfloat *	params
	)

Definition at line 70 of file fog.c.

{
   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" );
   }
}

Referenced by execute_list(), and init_exec_pointers().