ir_constant_visitor: Add support for dFdx and dFdy operations.

If the argument is a constant expression...it's not changing per pixel,
so the result is simply 0.

diff --git a/ir_constant_expression.cpp b/ir_constant_expression.cpp
index e89b5bc7685304c56ce5119edacaeb188a869e7e..4055a84ff151d869353d885d35c90c64eb531957 100644 (file)
--- a/ir_constant_expression.cpp
+++ b/ir_constant_expression.cpp
@@ -266,6 +266,15 @@ ir_constant_visitor::visit(ir_expression *ir)
       }
       break;
 
+   case ir_unop_dFdx:
+   case ir_unop_dFdy:
+      assert(op[0]->type->base_type == GLSL_TYPE_FLOAT);
+      type = ir->type;
+      for (c = 0; c < ir->operands[0]->type->components(); c++) {
+        f[c] = 0.0;
+      }
+      break;
+
    case ir_binop_add:
       if (ir->operands[0]->type == ir->operands[1]->type) {
         type = ir->operands[0]->type;