add GL_EXT_fog_coord support to radeon driver. No vtxfmt code (just uses fallback) yet. May cause a tcl fallback if fog coord is used together with separate specular lighting. Fog factors are precomputed and then submitted instead of the raw coords (chip limitation, same as on r200).

1 files changed, 85 insertions, 2 deletions

diff --git a/src/mesa/drivers/dri/radeon/radeon_tcl.c b/src/mesa/drivers/dri/radeon/radeon_tcl.c
index fb0f10a862..90383d4091 100644
--- a/src/mesa/drivers/dri/radeon/radeon_tcl.c
+++ b/src/mesa/drivers/dri/radeon/radeon_tcl.c
@@ -279,6 +279,88 @@ void radeonTclPrimitive( GLcontext *ctx,
    }
 }
 
+/**********************************************************************/
+/*             Fog blend factor computation for hw tcl                */
+/*             same calculation used as in t_vb_fog.c                 */
+/**********************************************************************/
+
+#define FOG_EXP_TABLE_SIZE 256
+#define FOG_MAX (10.0)
+#define EXP_FOG_MAX .0006595
+#define FOG_INCR (FOG_MAX/FOG_EXP_TABLE_SIZE)
+static GLfloat exp_table[FOG_EXP_TABLE_SIZE];
+
+#if 1
+#define NEG_EXP( result, narg )						\
+do {									\
+   GLfloat f = (GLfloat) (narg * (1.0/FOG_INCR));			\
+   GLint k = (GLint) f;							\
+   if (k > FOG_EXP_TABLE_SIZE-2) 					\
+      result = (GLfloat) EXP_FOG_MAX;					\
+   else									\
+      result = exp_table[k] + (f-k)*(exp_table[k+1]-exp_table[k]);	\
+} while (0)
+#else
+#define NEG_EXP( result, narg )					\
+do {								\
+   result = exp(-narg);						\
+} while (0)
+#endif
+
+
+/**
+ * Initialize the exp_table[] lookup table for approximating exp().
+ */
+void
+radeonInitStaticFogData( void )
+{
+   GLfloat f = 0.0F;
+   GLint i = 0;
+   for ( ; i < FOG_EXP_TABLE_SIZE ; i++, f += FOG_INCR) {
+      exp_table[i] = (GLfloat) exp(-f);
+   }
+}
+
+
+/**
+ * Compute per-vertex fog blend factors from fog coordinates by
+ * 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].
+ */
+float
+radeonComputeFogBlendFactor( GLcontext *ctx, GLfloat fogcoord )
+{
+   GLfloat end  = ctx->Fog.End;
+   GLfloat d, temp;
+   const GLfloat z = FABSF(fogcoord);
+
+   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);
+      temp = (end - z) * d;
+      return CLAMP(temp, 0.0F, 1.0F);
+      break;
+   case GL_EXP:
+      d = ctx->Fog.Density;
+      NEG_EXP( temp, d * z );
+      return temp;
+      break;
+   case GL_EXP2:
+      d = ctx->Fog.Density*ctx->Fog.Density;
+      NEG_EXP( temp, d * z * z );
+      return temp;
+      break;
+   default:
+      _mesa_problem(ctx, "Bad fog mode in make_fog_coord");
+      return 0;
+   }
+}
 
 /**********************************************************************/
 /*                          Render pipeline stage                     */
@@ -314,7 +396,7 @@ static GLboolean radeon_run_tcl_render( GLcontext *ctx,
       }
    }
 
-   if ( ctx->Fog.FogCoordinateSource == GL_FOG_COORD ) {
+   if ( (ctx->Fog.FogCoordinateSource == GL_FOG_COORD) && ctx->Fog.Enabled ) {
       inputs |= VERT_BIT_FOG;
    }
 
@@ -445,7 +527,8 @@ static char *fallbackStrings[] = {
    "Texgen unit 0",
    "Texgen unit 1",
    "Texgen unit 2",
-   "User disable"
+   "User disable",
+   "Fogcoord with separate specular lighting"
 };