Cycles: add ConstantFolder class for constant folding boilerplate.

Reviewed By: brecht, sergey

Differential Revision: https://developer.blender.org/D2089

intern/cycles/render/constant_fold.cpp

@@ -0,0 +1,122 @@
+/*
+ * Copyright 2011-2013 Blender Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "constant_fold.h"
+#include "graph.h"
+
+#include "util_foreach.h"
+
+CCL_NAMESPACE_BEGIN
+
+ConstantFolder::ConstantFolder(ShaderGraph *graph, ShaderNode *node, ShaderOutput *output)
+: graph(graph), node(node), output(output)
+{
+}
+
+bool ConstantFolder::all_inputs_constant() const
+{
+	foreach(ShaderInput *input, node->inputs) {
+		if(input->link) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+void ConstantFolder::make_constant(float value) const
+{
+	foreach(ShaderInput *sock, output->links) {
+		sock->set(value);
+	}
+
+	graph->disconnect(output);
+}
+
+void ConstantFolder::make_constant(float3 value) const
+{
+	foreach(ShaderInput *sock, output->links) {
+		sock->set(value);
+	}
+
+	graph->disconnect(output);
+}
+
+void ConstantFolder::make_constant_clamp(float value, bool clamp) const
+{
+	make_constant(clamp ? saturate(value) : value);
+}
+
+void ConstantFolder::make_constant_clamp(float3 value, bool clamp) const
+{
+	if (clamp) {
+		value.x = saturate(value.x);
+		value.y = saturate(value.y);
+		value.z = saturate(value.z);
+	}
+
+	make_constant(value);
+}
+
+void ConstantFolder::bypass(ShaderOutput *new_output) const
+{
+	assert(new_output);
+
+	/* Remove all outgoing links from socket and connect them to new_output instead.
+	 * The graph->relink method affects node inputs, so it's not safe to use in constant
+	 * folding if the node has multiple outputs and will thus be folded multiple times. */
+	vector<ShaderInput*> outputs = output->links;
+
+	graph->disconnect(output);
+
+	foreach(ShaderInput *sock, outputs) {
+		graph->connect(new_output, sock);
+	}
+}
+
+void ConstantFolder::discard() const
+{
+	assert(output->type() == SocketType::CLOSURE);
+	graph->disconnect(output);
+}
+
+void ConstantFolder::bypass_or_discard(ShaderInput *input) const
+{
+	assert(input->type() == SocketType::CLOSURE);
+
+	if (input->link) {
+		bypass(input->link);
+	}
+	else {
+		discard();
+	}
+}
+
+bool ConstantFolder::try_bypass_or_make_constant(ShaderInput *input, float3 input_value, bool clamp) const
+{
+	if(!input->link) {
+		make_constant_clamp(input_value, clamp);
+		return true;
+	}
+	else if(!clamp) {
+		bypass(input->link);
+		return true;
+	}
+
+	return false;
+}
+
+CCL_NAMESPACE_END