Shading: Add a clamp option to the Map Range node.

If the option is enabled, the output is clamped to the target range.
The target range is [To Min, To Max]. The option is enabled by default.

The clamp option is implemented in EEVEE by linking to the `clamp_value`
GLSL function. And it is implemented in Cycles using a graph expand
function.

Reviewers: brecht, JacquesLucke

Differential Revision: https://developer.blender.org/D5477

3 files changed, 22 insertions, 1 deletions

diff --git a/intern/cycles/blender/blender_shader.cpp b/intern/cycles/blender/blender_shader.cpp
index b1c61c2fa8c..b95e88573fa 100644
--- a/intern/cycles/blender/blender_shader.cpp
+++ b/intern/cycles/blender/blender_shader.cpp
@@ -316,7 +316,10 @@ static ShaderNode *add_node(Scene *scene,
     node = new RGBToBWNode();
   }
   else if (b_node.is_a(&RNA_ShaderNodeMapRange)) {
-    node = new MapRangeNode();
+    BL::ShaderNodeMapRange b_map_range_node(b_node);
+    MapRangeNode *map_range_node = new MapRangeNode();
+    map_range_node->clamp = b_map_range_node.clamp();
+    node = map_range_node;
   }
   else if (b_node.is_a(&RNA_ShaderNodeClamp)) {
     node = new ClampNode();
diff --git a/intern/cycles/render/nodes.cpp b/intern/cycles/render/nodes.cpp
index 18a7180c446..1a0225e19a8 100644
--- a/intern/cycles/render/nodes.cpp
+++ b/intern/cycles/render/nodes.cpp
@@ -5280,6 +5280,21 @@ MapRangeNode::MapRangeNode() : ShaderNode(node_type)
 {
 }
 
+void MapRangeNode::expand(ShaderGraph *graph)
+{
+  if (clamp) {
+    ShaderOutput *result_out = output("Result");
+    if (!result_out->links.empty()) {
+      ClampNode *clamp_node = new ClampNode();
+      clamp_node->min = to_min;
+      clamp_node->max = to_max;
+      graph->add(clamp_node);
+      graph->relink(result_out, clamp_node->output("Result"));
+      graph->connect(result_out, clamp_node->input("Value"));
+    }
+  }
+}
+
 void MapRangeNode::constant_fold(const ConstantFolder &folder)
 {
   if (folder.all_inputs_constant()) {
diff --git a/intern/cycles/render/nodes.h b/intern/cycles/render/nodes.h
index 9ac42ffc76c..d4708adf9af 100644
--- a/intern/cycles/render/nodes.h
+++ b/intern/cycles/render/nodes.h
@@ -1236,7 +1236,10 @@ class MapRangeNode : public ShaderNode {
   {
     return NODE_GROUP_LEVEL_3;
   }
+  void expand(ShaderGraph *graph);
+
   float value, from_min, from_max, to_min, to_max;
+  bool clamp;
 };
 
 class ClampNode : public ShaderNode {