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

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();

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()) {

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 {

source/blender/editors/space_node/drawnode.c

@@ -249,6 +249,11 @@ static void node_buts_texture(uiLayout *layout, bContext *UNUSED(C), PointerRNA
   }
 }
 
+static void node_buts_map_range(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
+{
+  uiItemR(layout, ptr, "clamp", 0, NULL, ICON_NONE);
+}
+
 static void node_buts_math(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
 {
   uiItemR(layout, ptr, "operation", 0, "", ICON_NONE);
@@ -1209,6 +1214,9 @@ static void node_shader_set_butfunc(bNodeType *ntype)
     case SH_NODE_VALTORGB:
       ntype->draw_buttons = node_buts_colorramp;
       break;
+    case SH_NODE_MAP_RANGE:
+      ntype->draw_buttons = node_buts_map_range;
+      break;
     case SH_NODE_MATH:
       ntype->draw_buttons = node_buts_math;
       break;

source/blender/makesrna/intern/rna_nodetree.c

@@ -3834,6 +3834,16 @@ static void def_frame(StructRNA *srna)
   RNA_def_property_update(prop, NC_NODE | ND_DISPLAY, NULL);
 }
 
+static void def_map_range(StructRNA *srna)
+{
+  PropertyRNA *prop;
+
+  prop = RNA_def_property(srna, "clamp", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "custom1", 1);
+  RNA_def_property_ui_text(prop, "Clamp", "Clamp the result to the target range [To Min, To Max]");
+  RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_update");
+}
+
 static void def_math(StructRNA *srna)
 {
   PropertyRNA *prop;

source/blender/nodes/NOD_static_types.h

@@ -50,7 +50,7 @@ DefNode(ShaderNode,     SH_NODE_MAPPING,         def_sh_mapping,         "MAPPIN
 DefNode(ShaderNode,     SH_NODE_CURVE_VEC,       def_vector_curve,       "CURVE_VEC",      VectorCurve,      "Vector Curves",     ""              )
 DefNode(ShaderNode,     SH_NODE_CURVE_RGB,       def_rgb_curve,          "CURVE_RGB",      RGBCurve,         "RGB Curves",        ""              )
 DefNode(ShaderNode,     SH_NODE_CAMERA,          0,                      "CAMERA",         CameraData,       "Camera Data",       ""              )
-DefNode(ShaderNode,     SH_NODE_MAP_RANGE,       0,                      "MAP_RANGE",      MapRange,         "Map Range",         ""              )
+DefNode(ShaderNode,     SH_NODE_MAP_RANGE,       def_map_range,          "MAP_RANGE",      MapRange,         "Map Range",         ""              )
 DefNode(ShaderNode,     SH_NODE_CLAMP,           0,                      "CLAMP",          Clamp,            "Clamp",             ""              )
 DefNode(ShaderNode,     SH_NODE_MATH,            def_math,               "MATH",           Math,             "Math",              ""              )
 DefNode(ShaderNode,     SH_NODE_VECT_MATH,       def_vector_math,        "VECT_MATH",      VectorMath,       "Vector Math",       ""              )

source/blender/nodes/shader/nodes/node_shader_map_range.c

@@ -37,13 +37,22 @@ static bNodeSocketTemplate sh_node_map_range_out[] = {
     {-1, 0, ""},
 };
 
+static void node_shader_init_map_range(bNodeTree *UNUSED(ntree), bNode *node)
+{
+  node->custom1 = true;
+}
+
 static int gpu_shader_map_range(GPUMaterial *mat,
                                 bNode *node,
                                 bNodeExecData *UNUSED(execdata),
                                 GPUNodeStack *in,
                                 GPUNodeStack *out)
 {
-  return GPU_stack_link(mat, node, "map_range", in, out);
+  GPU_stack_link(mat, node, "map_range", in, out);
+  if (node->custom1) {
+    GPU_link(mat, "clamp_value", out[0].link, in[3].link, in[4].link, &out[0].link);
+  }
+  return 1;
 }
 
 void register_node_type_sh_map_range(void)
@@ -52,6 +61,7 @@ void register_node_type_sh_map_range(void)
 
   sh_node_type_base(&ntype, SH_NODE_MAP_RANGE, "Map Range", NODE_CLASS_CONVERTOR, 0);
   node_type_socket_templates(&ntype, sh_node_map_range_in, sh_node_map_range_out);
+  node_type_init(&ntype, node_shader_init_map_range);
   node_type_gpu(&ntype, gpu_shader_map_range);
 
   nodeRegisterType(&ntype);