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-rw-r--r--src/mesa/state_tracker/st_glsl_to_tgsi.cpp24
1 files changed, 22 insertions, 2 deletions
diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index 45136ded2bc..fcd69b18d3a 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -1448,9 +1448,29 @@ glsl_to_tgsi_visitor::visit(ir_expression *ir)
emit(ir, TGSI_OPCODE_DDX, result_dst, op[0]);
break;
case ir_unop_dFdy:
- op[0].negate = ~op[0].negate;
- emit(ir, TGSI_OPCODE_DDY, result_dst, op[0]);
+ {
+ /* The X component contains 1 or -1 depending on whether the framebuffer
+ * is a FBO or the window system buffer, respectively.
+ * It is then multiplied with the source operand of DDY.
+ */
+ static const gl_state_index transform_y_state[STATE_LENGTH]
+ = { STATE_INTERNAL, STATE_FB_WPOS_Y_TRANSFORM };
+
+ unsigned transform_y_index =
+ _mesa_add_state_reference(this->prog->Parameters,
+ transform_y_state);
+
+ st_src_reg transform_y = st_src_reg(PROGRAM_STATE_VAR,
+ transform_y_index,
+ glsl_type::vec4_type);
+ transform_y.swizzle = SWIZZLE_XXXX;
+
+ st_src_reg temp = get_temp(glsl_type::vec4_type);
+
+ emit(ir, TGSI_OPCODE_MUL, st_dst_reg(temp), transform_y, op[0]);
+ emit(ir, TGSI_OPCODE_DDY, result_dst, temp);
break;
+ }
case ir_unop_noise: {
/* At some point, a motivated person could add a better