r300: Fix fogcoord rewriting

We only care about the actual fogcoord itself now, reducing the rewriting
done for the vertex program.

The rewriting of source operand swizzles in the fragment program takes
care that fogcoord.yzw = 001.

This should fix fogcoord rewriting entirely, which had been horribly
broken in the face of dot-product instructions, and just broken (though
not horribly so) in the face of almost every other instruction (the W
component would be incorrect for most arithmetic instructions).

Signed-off-by: Nicolai Hähnle <nhaehnle@gmail.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/src/mesa/drivers/dri/r300/r300_fragprog_common.c b/src/mesa/drivers/dri/r300/r300_fragprog_common.c
index c7914649dd..f5c4c0f4a0 100644
--- a/src/mesa/drivers/dri/r300/r300_fragprog_common.c
+++ b/src/mesa/drivers/dri/r300/r300_fragprog_common.c
@@ -162,6 +162,14 @@ static void insert_WPOS_trailer(struct r300_fragment_program_compiler *compiler)
 	}
 }
 
+
+/**
+ * Rewrite fragment.fogcoord to use a texture coordinate slot.
+ * Note that fogcoord is forced into an X001 pattern, and this enforcement
+ * is done here.
+ *
+ * See also the counterpart rewriting for vertex programs.
+ */
 static void rewriteFog(struct r300_fragment_program_compiler *compiler)
 {
 	struct r300_fragment_program *fp = compiler->fp;
@@ -193,8 +201,12 @@ static void rewriteFog(struct r300_fragment_program_compiler *compiler)
 		while (inst->Opcode != OPCODE_END) {
 			const int src_regs = _mesa_num_inst_src_regs(inst->Opcode);
 			for (i = 0; i < src_regs; ++i) {
-				if (inst->SrcReg[i].File == PROGRAM_INPUT && inst->SrcReg[i].Index == FRAG_ATTRIB_FOGC)
+				if (inst->SrcReg[i].File == PROGRAM_INPUT && inst->SrcReg[i].Index == FRAG_ATTRIB_FOGC) {
 					inst->SrcReg[i].Index = fp->fog_attr;
+					inst->SrcReg[i].Swizzle = combine_swizzles(
+						MAKE_SWIZZLE4(SWIZZLE_X, SWIZZLE_ZERO, SWIZZLE_ZERO, SWIZZLE_ONE),
+						inst->SrcReg[i].Swizzle);
+				}
 			}
 			++inst;
 		}