ir_to_mesa: Handle shadow compare w/projection and LOD bias correctly

The code would previously handle the projection, then swizzle the
shadow comparitor into place.  However, when the projection is done
"by hand," as in the TXB case, the unprojected shadow comparitor would
over-write the projected shadow comparitor.

Shadow comparison with projection and LOD is an extremely rare case in
real application code, so it shouldn't matter that we don't handle
that case with the greatest efficiency.

NOTE: This is a candidate for the stable branches.

Reviewed-by: Brian Paul <brianp@vmware.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=32395

diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
index bf2513d474897f5437054a2f7b29c16560f10f34..7c1ae46ff33fa9f78d8d7b770702a94a53e8b43c 100644 (file)
--- a/src/mesa/program/ir_to_mesa.cpp
+++ b/src/mesa/program/ir_to_mesa.cpp
@@ -2084,15 +2084,39 @@ ir_to_mesa_visitor::visit(ir_texture *ir)
         coord_dst.writemask = WRITEMASK_W;
         ir_to_mesa_emit_op1(ir, OPCODE_RCP, coord_dst, projector);
 
+        /* In the case where we have to project the coordinates "by hand,"
+         * the shadow comparitor value must also be projected.
+         */
+        ir_to_mesa_src_reg tmp_src = coord;
+        if (ir->shadow_comparitor) {
+           /* Slot the shadow value in as the second to last component of the
+            * coord.
+            */
+           ir->shadow_comparitor->accept(this);
+
+           tmp_src = get_temp(glsl_type::vec4_type);
+           ir_to_mesa_dst_reg tmp_dst = ir_to_mesa_dst_reg_from_src(tmp_src);
+
+           tmp_dst.writemask = WRITEMASK_Z;
+           ir_to_mesa_emit_op1(ir, OPCODE_MOV, tmp_dst, this->result);
+
+           tmp_dst.writemask = WRITEMASK_XY;
+           ir_to_mesa_emit_op1(ir, OPCODE_MOV, tmp_dst, coord);
+        }
+
         coord_dst.writemask = WRITEMASK_XYZ;
-        ir_to_mesa_emit_op2(ir, OPCODE_MUL, coord_dst, coord, coord_w);
+        ir_to_mesa_emit_op2(ir, OPCODE_MUL, coord_dst, tmp_src, coord_w);
 
         coord_dst.writemask = WRITEMASK_XYZW;
         coord.swizzle = SWIZZLE_XYZW;
       }
    }
 
-   if (ir->shadow_comparitor) {
+   /* If projection is done and the opcode is not OPCODE_TXP, then the shadow
+    * comparitor was put in the correct place (and projected) by the code,
+    * above, that handles by-hand projection.
+    */
+   if (ir->shadow_comparitor && (!ir->projector || opcode == OPCODE_TXP)) {
       /* Slot the shadow value in as the second to last component of the
        * coord.
        */