mesa: Kill gl_fragment_program::FogOption with fire

All drivers expect this to always be GL_NONE.  Don't let there be any
opportunity for a bad value to leak out and infect some unsuspecting
driver.  If any driver for hardware that had fixed-function
per-fragment fog (i915 and perhaps some r300-ish) was ever going to
add support, it would have done it by now.

Reviewed-by: Eric Anholt <[email protected]>
Acked-by: Corbin Simpson <[email protected]>
Acked-by: Alex Deucher <[email protected]>

4 files changed, 30 insertions, 26 deletions

diff --git a/src/mesa/program/arbprogparse.c b/src/mesa/program/arbprogparse.c
index 7f778c3c381..dffc8abf735 100644
--- a/src/mesa/program/arbprogparse.c
+++ b/src/mesa/program/arbprogparse.c
@@ -116,20 +116,11 @@ _mesa_parse_arb_fragment_program(struct gl_context* ctx, GLenum target,
          program->Base.SamplersUsed |= (1 << i);
    }
    program->Base.ShadowSamplers = prog.ShadowSamplers;
-   switch (state.option.Fog) {
-   case OPTION_FOG_EXP:    program->FogOption = GL_EXP;    break;
-   case OPTION_FOG_EXP2:   program->FogOption = GL_EXP2;   break;
-   case OPTION_FOG_LINEAR: program->FogOption = GL_LINEAR; break;
-   default:                program->FogOption = GL_NONE;   break;
-   }
    program->OriginUpperLeft = state.option.OriginUpperLeft;
    program->PixelCenterInteger = state.option.PixelCenterInteger;
 
    program->UsesKill            = state.fragment.UsesKill;
 
-   if (program->FogOption)
-      program->Base.InputsRead |= FRAG_BIT_FOGC;
-
    if (program->Base.Instructions)
       free(program->Base.Instructions);
    program->Base.Instructions = prog.Instructions;
@@ -143,12 +134,15 @@ _mesa_parse_arb_fragment_program(struct gl_context* ctx, GLenum target,
     * there's no hardware that wants to do fog in a discrete stage separate
     * from the fragment shader.
     */
-   if (program->FogOption != GL_NONE) {
+   if (state.option.Fog != OPTION_NONE) {
+      static const GLenum fog_modes[4] = {
+	 GL_NONE, GL_EXP, GL_EXP2, GL_LINEAR
+      };
+
       /* XXX: we should somehow recompile this to remove clamping if disabled
        * On the ATI driver, this is unclampled if fragment clamping is disabled
        */
-      _mesa_append_fog_code(ctx, program, GL_TRUE);
-      program->FogOption = GL_NONE;
+      _mesa_append_fog_code(ctx, program, fog_modes[state.option.Fog], GL_TRUE);
    }
 
 #if DEBUG_FP
diff --git a/src/mesa/program/program.c b/src/mesa/program/program.c
index 5b014872ed4..78efca9f122 100644
--- a/src/mesa/program/program.c
+++ b/src/mesa/program/program.c
@@ -557,7 +557,6 @@ _mesa_clone_program(struct gl_context *ctx, const struct gl_program *prog)
          const struct gl_fragment_program *fp
             = (const struct gl_fragment_program *) prog;
          struct gl_fragment_program *fpc = (struct gl_fragment_program *) clone;
-         fpc->FogOption = fp->FogOption;
          fpc->UsesKill = fp->UsesKill;
          fpc->OriginUpperLeft = fp->OriginUpperLeft;
          fpc->PixelCenterInteger = fp->PixelCenterInteger;
diff --git a/src/mesa/program/programopt.c b/src/mesa/program/programopt.c
index 5ad9571f757..a239da2c609 100644
--- a/src/mesa/program/programopt.c
+++ b/src/mesa/program/programopt.c
@@ -230,15 +230,25 @@ _mesa_insert_mvp_code(struct gl_context *ctx, struct gl_vertex_program *vprog)
 
 
 /**
- * Append extra instructions onto the given fragment program to implement
- * the fog mode specified by fprog->FogOption.
- * The fragment.fogcoord input is used to compute the fog blend factor.
+ * Append instructions to implement fog
  *
- * XXX with a little work, this function could be adapted to add fog code
+ * The \c fragment.fogcoord input is used to compute the fog blend factor.
+ *
+ * \param ctx      The GL context
+ * \param fprog    Fragment program that fog instructions will be appended to.
+ * \param fog_mode Fog mode.  One of \c GL_EXP, \c GL_EXP2, or \c GL_LINEAR.
+ * \param saturate True if writes to color outputs should be clamped to [0, 1]
+ *
+ * \note
+ * This function sets \c FRAG_BIT_FOGC in \c fprog->Base.InputsRead.
+ *
+ * \todo With a little work, this function could be adapted to add fog code
  * to vertex programs too.
  */
 void
-_mesa_append_fog_code(struct gl_context *ctx, struct gl_fragment_program *fprog, GLboolean saturate)
+_mesa_append_fog_code(struct gl_context *ctx,
+		      struct gl_fragment_program *fprog, GLenum fog_mode,
+		      GLboolean saturate)
 {
    static const gl_state_index fogPStateOpt[STATE_LENGTH]
       = { STATE_INTERNAL, STATE_FOG_PARAMS_OPTIMIZED, 0, 0, 0 };
@@ -251,9 +261,9 @@ _mesa_append_fog_code(struct gl_context *ctx, struct gl_fragment_program *fprog,
    GLint fogPRefOpt, fogColorRef; /* state references */
    GLuint colorTemp, fogFactorTemp; /* temporary registerss */
 
-   if (fprog->FogOption == GL_NONE) {
+   if (fog_mode == GL_NONE) {
       _mesa_problem(ctx, "_mesa_append_fog_code() called for fragment program"
-                    " with FogOption == GL_NONE");
+                    " with fog_mode == GL_NONE");
       return;
    }
 
@@ -301,7 +311,7 @@ _mesa_append_fog_code(struct gl_context *ctx, struct gl_fragment_program *fprog,
 
    /* emit instructions to compute fog blending factor */
    /* this is always clamped to [0, 1] regardless of fragment clamping */
-   if (fprog->FogOption == GL_LINEAR) {
+   if (fog_mode == GL_LINEAR) {
       /* MAD fogFactorTemp.x, fragment.fogcoord.x, fogPRefOpt.x, fogPRefOpt.y; */
       inst->Opcode = OPCODE_MAD;
       inst->DstReg.File = PROGRAM_TEMPORARY;
@@ -320,7 +330,7 @@ _mesa_append_fog_code(struct gl_context *ctx, struct gl_fragment_program *fprog,
       inst++;
    }
    else {
-      ASSERT(fprog->FogOption == GL_EXP || fprog->FogOption == GL_EXP2);
+      ASSERT(fog_mode == GL_EXP || fog_mode == GL_EXP2);
       /* fogPRefOpt.z = d/ln(2), fogPRefOpt.w = d/sqrt(ln(2) */
       /* EXP: MUL fogFactorTemp.x, fogPRefOpt.z, fragment.fogcoord.x; */
       /* EXP2: MUL fogFactorTemp.x, fogPRefOpt.w, fragment.fogcoord.x; */
@@ -331,12 +341,12 @@ _mesa_append_fog_code(struct gl_context *ctx, struct gl_fragment_program *fprog,
       inst->SrcReg[0].File = PROGRAM_STATE_VAR;
       inst->SrcReg[0].Index = fogPRefOpt;
       inst->SrcReg[0].Swizzle
-         = (fprog->FogOption == GL_EXP) ? SWIZZLE_ZZZZ : SWIZZLE_WWWW;
+         = (fog_mode == GL_EXP) ? SWIZZLE_ZZZZ : SWIZZLE_WWWW;
       inst->SrcReg[1].File = PROGRAM_INPUT;
       inst->SrcReg[1].Index = FRAG_ATTRIB_FOGC;
       inst->SrcReg[1].Swizzle = SWIZZLE_XXXX;
       inst++;
-      if (fprog->FogOption == GL_EXP2) {
+      if (fog_mode == GL_EXP2) {
          /* MUL fogFactorTemp.x, fogFactorTemp.x, fogFactorTemp.x; */
          inst->Opcode = OPCODE_MUL;
          inst->DstReg.File = PROGRAM_TEMPORARY;
@@ -397,7 +407,6 @@ _mesa_append_fog_code(struct gl_context *ctx, struct gl_fragment_program *fprog,
    fprog->Base.Instructions = newInst;
    fprog->Base.NumInstructions = inst - newInst;
    fprog->Base.InputsRead |= FRAG_BIT_FOGC;
-   /* XXX do this?  fprog->FogOption = GL_NONE; */
 }
 
 
diff --git a/src/mesa/program/programopt.h b/src/mesa/program/programopt.h
index 79631aa5843..b9205823c29 100644
--- a/src/mesa/program/programopt.h
+++ b/src/mesa/program/programopt.h
@@ -32,7 +32,9 @@ extern void
 _mesa_insert_mvp_code(struct gl_context *ctx, struct gl_vertex_program *vprog);
 
 extern void
-_mesa_append_fog_code(struct gl_context *ctx, struct gl_fragment_program *fprog, GLboolean saturate);
+_mesa_append_fog_code(struct gl_context *ctx,
+		      struct gl_fragment_program *fprog, GLenum fog_mode,
+		      GLboolean saturate);
 
 extern void
 _mesa_count_texture_indirections(struct gl_program *prog);