fix mixed texgen/non-texgen with texgen modes requiring plane parameters (GL_OBJECT_LINEAR, GL_EYE_LINEAR). This is a chip limitation, try to hack it up regardless or use a tcl fallback in some cases. Might still produce wrong results if fixed up, but so far this corrects celestia ring shadows (in multitexture mode), doom3 (arb renderer), quake4 (arb renderer and some less visible bugs in r200 renderer), and even the remaining texgenmix broken case (this is pure luck though, it is easy to construct artifical cases where it will break).

src/mesa/drivers/dri/r200/r200_texstate.c

@@ -1216,6 +1216,47 @@ static void set_texgen_matrix( r200ContextPtr rmesa,
 }
 
 
+static GLuint r200_need_dis_texgen(const GLbitfield texGenEnabled,
+				   const GLfloat *planeS,
+				   const GLfloat *planeT,
+				   const GLfloat *planeR,
+				   const GLfloat *planeQ)
+{
+   GLuint needtgenable = 0;
+
+   if (!(texGenEnabled & S_BIT)) {
+      if (((texGenEnabled & T_BIT) && planeT[0] != 0.0) ||
+	 ((texGenEnabled & R_BIT) && planeR[0] != 0.0) ||
+	 ((texGenEnabled & Q_BIT) && planeQ[0] != 0.0)) {
+	 needtgenable |= S_BIT;
+      }
+   }
+   if (!(texGenEnabled & T_BIT)) {
+      if (((texGenEnabled & S_BIT) && planeS[1] != 0.0) ||
+	 ((texGenEnabled & R_BIT) && planeR[1] != 0.0) ||
+	 ((texGenEnabled & Q_BIT) && planeQ[1] != 0.0)) {
+	 needtgenable |= T_BIT;
+     }
+   }
+   if (!(texGenEnabled & R_BIT)) {
+      if (((texGenEnabled & S_BIT) && planeS[2] != 0.0) ||
+	 ((texGenEnabled & T_BIT) && planeT[2] != 0.0) ||
+	 ((texGenEnabled & Q_BIT) && planeQ[2] != 0.0)) {
+	 needtgenable |= R_BIT;
+      }
+   }
+   if (!(texGenEnabled & Q_BIT)) {
+      if (((texGenEnabled & S_BIT) && planeS[3] != 0.0) ||
+	 ((texGenEnabled & T_BIT) && planeT[3] != 0.0) ||
+	 ((texGenEnabled & R_BIT) && planeR[3] != 0.0)) {
+	 needtgenable |= Q_BIT;
+      }
+   }
+
+   return needtgenable;
+}
+
+
 /*
  * Returns GL_FALSE if fallback required.  
  */
@@ -1285,28 +1326,72 @@ static GLboolean r200_validate_texgen( GLcontext *ctx, GLuint unit )
       return GL_FALSE;
    }
 
+/* we CANNOT do mixed mode if the texgen mode requires a plane where the input
+   is not enabled for texgen, since the planes are concatenated into texmat,
+   and thus the input will come from texcoord rather than tex gen equation!
+   Either fallback or just hope that those texcoords aren't really needed...
+   Assuming the former will cause lots of unnecessary fallbacks, the latter will
+   generate bogus results sometimes - it's pretty much impossible to really know
+   when a fallback is needed, depends on texmat and what sort of texture is bound
+   etc, - for now fallback if we're missing either S or T bits, there's a high
+   probability we need the texcoords in that case.
+   That's a lot of work for some obscure texgen mixed mode fixup - why oh why
+   doesn't the chip just directly accept the plane parameters :-(. */
    switch (mode) {
-   case GL_OBJECT_LINEAR:
+   case GL_OBJECT_LINEAR: {
+      GLuint needtgenable = r200_need_dis_texgen( texUnit->TexGenEnabled,
+				texUnit->ObjectPlaneS, texUnit->ObjectPlaneT,
+				texUnit->ObjectPlaneR, texUnit->ObjectPlaneQ );
+      if (needtgenable & (S_BIT | T_BIT)) {
+	 if (R200_DEBUG & DEBUG_FALLBACKS)
+	 fprintf(stderr, "fallback mixed texgen / obj plane, 0x%x\n",
+		 texUnit->TexGenEnabled);
+	 return GL_FALSE;
+      }
+      if (needtgenable & (R_BIT)) {
+	 tgcm &= ~(R200_TEXGEN_COMP_R << (unit * 4));
+      }
+      if (needtgenable & (Q_BIT)) {
+	 tgcm &= ~(R200_TEXGEN_COMP_Q << (unit * 4));
+      }
+
       tgi |= R200_TEXGEN_INPUT_OBJ << inputshift;
       set_texgen_matrix( rmesa, unit, 
 	 (texUnit->TexGenEnabled & S_BIT) ? texUnit->ObjectPlaneS : I,
 	 (texUnit->TexGenEnabled & T_BIT) ? texUnit->ObjectPlaneT : I + 4,
 	 (texUnit->TexGenEnabled & R_BIT) ? texUnit->ObjectPlaneR : I + 8,
 	 (texUnit->TexGenEnabled & Q_BIT) ? texUnit->ObjectPlaneQ : I + 12);
+      }
       break;
 
-   case GL_EYE_LINEAR:
+   case GL_EYE_LINEAR: {
+      GLuint needtgenable = r200_need_dis_texgen( texUnit->TexGenEnabled,
+				texUnit->EyePlaneS, texUnit->EyePlaneT,
+				texUnit->EyePlaneR, texUnit->EyePlaneQ );
+      if (needtgenable & (S_BIT | T_BIT)) {
+	 if (R200_DEBUG & DEBUG_FALLBACKS)
+	 fprintf(stderr, "fallback mixed texgen / eye plane, 0x%x\n",
+		 texUnit->TexGenEnabled);
+	 return GL_FALSE;
+      }
+      if (needtgenable & (R_BIT)) {
+	 tgcm &= ~(R200_TEXGEN_COMP_R << (unit * 4));
+      }
+      if (needtgenable & (Q_BIT)) {
+	 tgcm &= ~(R200_TEXGEN_COMP_Q << (unit * 4));
+      }
       tgi |= R200_TEXGEN_INPUT_EYE << inputshift;
-      set_texgen_matrix( rmesa, unit, 
+      set_texgen_matrix( rmesa, unit,
 	 (texUnit->TexGenEnabled & S_BIT) ? texUnit->EyePlaneS : I,
 	 (texUnit->TexGenEnabled & T_BIT) ? texUnit->EyePlaneT : I + 4,
 	 (texUnit->TexGenEnabled & R_BIT) ? texUnit->EyePlaneR : I + 8,
 	 (texUnit->TexGenEnabled & Q_BIT) ? texUnit->EyePlaneQ : I + 12);
+      }
       break;
 
    case GL_REFLECTION_MAP_NV:
       rmesa->TexGenNeedNormals[unit] = GL_TRUE;
-      tgi |= R200_TEXGEN_INPUT_EYE_REFLECT<<inputshift;
+      tgi |= R200_TEXGEN_INPUT_EYE_REFLECT << inputshift;
       /* pretty weird, must only negate when lighting is enabled? */
       if (ctx->Light.Enabled)
 	 set_texgen_matrix( rmesa, unit,