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Diffstat (limited to 'src/mesa/swrast/s_fog.c')
-rw-r--r--src/mesa/swrast/s_fog.c78
1 files changed, 56 insertions, 22 deletions
diff --git a/src/mesa/swrast/s_fog.c b/src/mesa/swrast/s_fog.c
index 4b8c4f0c71..74431d89b9 100644
--- a/src/mesa/swrast/s_fog.c
+++ b/src/mesa/swrast/s_fog.c
@@ -1,4 +1,4 @@
-/* $Id: s_fog.c,v 1.12 2001/05/03 22:13:32 brianp Exp $ */
+/* $Id: s_fog.c,v 1.13 2001/06/18 23:55:18 brianp Exp $ */
/*
* Mesa 3-D graphics library
@@ -36,10 +36,44 @@
#include "s_pb.h"
+
+
+/*
+ * Used to convert current raster distance to a fog factor in [0,1].
+ */
+GLfloat
+_mesa_z_to_fogfactor(GLcontext *ctx, GLfloat z)
+{
+ GLfloat d, f;
+
+ switch (ctx->Fog.Mode) {
+ case GL_LINEAR:
+ if (ctx->Fog.Start == ctx->Fog.End)
+ d = 1.0F;
+ else
+ d = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
+ f = (ctx->Fog.End - z) * d;
+ return CLAMP(f, 0.0F, 1.0F);
+ case GL_EXP:
+ d = ctx->Fog.Density;
+ f = exp(-d * z);
+ return f;
+ case GL_EXP2:
+ d = ctx->Fog.Density;
+ f = exp(-(d * d * z * z));
+ return f;
+ default:
+ _mesa_problem(ctx, "Bad fog mode in make_fog_coord");
+ return 0.0;
+ }
+}
+
+
+
/*
* Apply fog to an array of RGBA pixels.
* Input: n - number of pixels
- * fog - array of interpolated screen-space fog coordinates in [0..1]
+ * fog - array of fog factors in [0,1]
* red, green, blue, alpha - pixel colors
* Output: red, green, blue, alpha - fogged pixel colors
*/
@@ -70,7 +104,7 @@ _mesa_fog_rgba_pixels( const GLcontext *ctx,
/*
* Apply fog to an array of color index pixels.
* Input: n - number of pixels
- * z - array of integer depth values
+ * fog - array of fog factors in [0,1]
* index - pixel color indexes
* Output: index - fogged pixel color indexes
*/
@@ -90,7 +124,7 @@ _mesa_fog_ci_pixels( const GLcontext *ctx,
/*
- * Calculate fog coords from window z values
+ * Calculate fog factors (in [0,1]) from window z values
* Input: n - number of pixels
* z - array of integer depth values
* red, green, blue, alpha - pixel colors
@@ -98,11 +132,11 @@ _mesa_fog_ci_pixels( const GLcontext *ctx,
*
* Use lookup table & interpolation?
*/
-void
-_mesa_win_fog_coords_from_z( const GLcontext *ctx,
- GLuint n,
- const GLdepth z[],
- GLfloat fogcoord[] )
+static void
+compute_fog_factors_from_z( const GLcontext *ctx,
+ GLuint n,
+ const GLdepth z[],
+ GLfloat fogFact[] )
{
const GLboolean ortho = (ctx->ProjectionMatrix.m[15] != 0.0F);
const GLfloat p10 = ctx->ProjectionMatrix.m[10];
@@ -154,7 +188,7 @@ _mesa_win_fog_coords_from_z( const GLcontext *ctx,
GLfloat eyez = (ndcz - p14) / p10;
if (eyez < 0.0)
eyez = -eyez;
- fogcoord[i] = (fogEnd - eyez) * fogScale;
+ fogFact[i] = (fogEnd - eyez) * fogScale;
}
}
else {
@@ -164,7 +198,7 @@ _mesa_win_fog_coords_from_z( const GLcontext *ctx,
GLfloat eyez = p14 / (ndcz + p10);
if (eyez < 0.0)
eyez = -eyez;
- fogcoord[i] = (fogEnd - eyez) * fogScale;
+ fogFact[i] = (fogEnd - eyez) * fogScale;
}
}
}
@@ -176,7 +210,7 @@ _mesa_win_fog_coords_from_z( const GLcontext *ctx,
GLfloat eyez = (ndcz - p14) / p10;
if (eyez < 0.0)
eyez = -eyez;
- fogcoord[i] = exp( -ctx->Fog.Density * eyez );
+ fogFact[i] = exp( -ctx->Fog.Density * eyez );
}
}
else {
@@ -186,7 +220,7 @@ _mesa_win_fog_coords_from_z( const GLcontext *ctx,
GLfloat eyez = p14 / (ndcz + p10);
if (eyez < 0.0)
eyez = -eyez;
- fogcoord[i] = exp( -ctx->Fog.Density * eyez );
+ fogFact[i] = exp( -ctx->Fog.Density * eyez );
}
}
break;
@@ -203,7 +237,7 @@ _mesa_win_fog_coords_from_z( const GLcontext *ctx,
if (tmp < FLT_MIN_10_EXP)
tmp = FLT_MIN_10_EXP;
#endif
- fogcoord[i] = exp( tmp );
+ fogFact[i] = exp( tmp );
}
}
else {
@@ -217,13 +251,13 @@ _mesa_win_fog_coords_from_z( const GLcontext *ctx,
if (tmp < FLT_MIN_10_EXP)
tmp = FLT_MIN_10_EXP;
#endif
- fogcoord[i] = exp( tmp );
+ fogFact[i] = exp( tmp );
}
}
}
break;
default:
- _mesa_problem(ctx, "Bad fog mode in _mesa_win_fog_coords_from_z");
+ _mesa_problem(ctx, "Bad fog mode in compute_fog_factors_from_z");
return;
}
}
@@ -240,10 +274,10 @@ void
_mesa_depth_fog_rgba_pixels( const GLcontext *ctx,
GLuint n, const GLdepth z[], GLchan rgba[][4] )
{
- GLfloat fog[PB_SIZE];
+ GLfloat fogFact[PB_SIZE];
ASSERT(n <= PB_SIZE);
- _mesa_win_fog_coords_from_z( ctx, n, z, fog );
- _mesa_fog_rgba_pixels( ctx, n, fog, rgba );
+ compute_fog_factors_from_z( ctx, n, z, fogFact );
+ _mesa_fog_rgba_pixels( ctx, n, fogFact, rgba );
}
@@ -258,8 +292,8 @@ void
_mesa_depth_fog_ci_pixels( const GLcontext *ctx,
GLuint n, const GLdepth z[], GLuint index[] )
{
- GLfloat fog[PB_SIZE];
+ GLfloat fogFact[PB_SIZE];
ASSERT(n <= PB_SIZE);
- _mesa_win_fog_coords_from_z( ctx, n, z, fog );
- _mesa_fog_ci_pixels( ctx, n, fog, index );
+ compute_fog_factors_from_z( ctx, n, z, fogFact );
+ _mesa_fog_ci_pixels( ctx, n, fogFact, index );
}