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use ABS(Z) when computing blend factors

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This commit is contained in:
Brian Paul
2004-02-25 16:14:16 +00:00
parent 20e25ca50a
commit 54056db8db
1 changed files with 4 additions and 4 deletions
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src/mesa/tnl/t_vb_fog.c
+4 -4
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@@ -91,6 +91,7 @@ init_static_data( void )
* evaluating the GL_LINEAR, GL_EXP or GL_EXP2 fog function.
* Fog coordinates are distances from the eye (typically between the
* near and far clip plane distances).
* Note the fog (eye Z) coords may be negative so we use ABS(z) below.
* Fog blend factors are in the range [0,1].
*/
static void
@@ -113,7 +114,7 @@ compute_fog_blend_factors(GLcontext *ctx, GLvector4f *out, const GLvector4f *in)
else
d = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) {
const GLfloat z = *v;
const GLfloat z = FABSF(*v);
GLfloat f = (end - z) * d;
data[i][0] = CLAMP(f, 0.0F, 1.0F);
}
@@ -121,14 +122,14 @@ compute_fog_blend_factors(GLcontext *ctx, GLvector4f *out, const GLvector4f *in)
case GL_EXP:
d = ctx->Fog.Density;
for ( i = 0 ; i < n ; i++, STRIDE_F(v,stride)) {
const GLfloat z = *v;
const GLfloat z = FABSF(*v);
NEG_EXP( data[i][0], d * z );
}
break;
case GL_EXP2:
d = ctx->Fog.Density*ctx->Fog.Density;
for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) {
const GLfloat z = *v;
const GLfloat z = FABSF(*v);
NEG_EXP( data[i][0], d * z * z );
}
break;
@@ -170,7 +171,6 @@ run_fog_stage(GLcontext *ctx, struct tnl_pipeline_stage *stage)
plane[1] = -m[6];
plane[2] = -m[10];
plane[3] = -m[14];
/* Full eye coords weren't required, just calculate the
* eye Z values.
*/