intern/cycles/kernel/osl/shaders/node_subsurface_scattering.osl

@@ -8,6 +8,7 @@ shader node_subsurface_scattering(color Color = 0.8,
                                   float Scale = 1.0,
                                   vector Radius = vector(0.1, 0.1, 0.1),
                                   float IOR = 1.4,
+                                  float Roughness = 1.0,
                                   float Anisotropy = 0.0,
                                   string method = "random_walk",
                                   normal Normal = N,
@@ -23,5 +24,5 @@ shader node_subsurface_scattering(color Color = 0.8,
                                "anisotropy",
                                Anisotropy,
                                "roughness",
-                               1.0);
+                               clamp(Roughness, 0.0, 1.0));
 }

intern/cycles/kernel/svm/closure.h

@@ -872,7 +872,7 @@ ccl_device
         bssrdf->albedo = closure_weight;
         bssrdf->N = maybe_ensure_valid_specular_reflection(sd, N);
         bssrdf->ior = param2;
-        bssrdf->alpha = 1.0f;
+        bssrdf->alpha = saturatef(stack_load_float(stack, data_node.w));
         bssrdf->anisotropy = stack_load_float(stack, data_node.z);
 
         sd->flag |= bssrdf_setup(sd, bssrdf, path_flag, (ClosureType)type);

intern/cycles/scene/shader_nodes.cpp

@@ -2899,6 +2899,7 @@ NODE_DEFINE(SubsurfaceScatteringNode)
   SOCKET_IN_VECTOR(radius, "Radius", make_float3(0.1f, 0.1f, 0.1f));
 
   SOCKET_IN_FLOAT(subsurface_ior, "IOR", 1.4f);
+  SOCKET_IN_FLOAT(subsurface_roughness, "Roughness", 1.0f);
   SOCKET_IN_FLOAT(subsurface_anisotropy, "Anisotropy", 0.0f);
 
   SOCKET_OUT_CLOSURE(BSSRDF, "BSSRDF");
@@ -2914,7 +2915,12 @@ SubsurfaceScatteringNode::SubsurfaceScatteringNode() : BsdfNode(get_node_type())
 void SubsurfaceScatteringNode::compile(SVMCompiler &compiler)
 {
   closure = method;
-  BsdfNode::compile(compiler, input("Scale"), input("IOR"), input("Radius"), input("Anisotropy"));
+  BsdfNode::compile(compiler,
+                    input("Scale"),
+                    input("IOR"),
+                    input("Radius"),
+                    input("Anisotropy"),
+                    input("Roughness"));
 }
 
 void SubsurfaceScatteringNode::compile(OSLCompiler &compiler)

intern/cycles/scene/shader_nodes.h

@@ -653,6 +653,7 @@ class SubsurfaceScatteringNode : public BsdfNode {
   NODE_SOCKET_API(float, scale)
   NODE_SOCKET_API(float3, radius)
   NODE_SOCKET_API(float, subsurface_ior)
+  NODE_SOCKET_API(float, subsurface_roughness)
   NODE_SOCKET_API(float, subsurface_anisotropy)
   NODE_SOCKET_API(ClosureType, method)
 };

source/blender/blenkernel/BKE_blender_version.h

@@ -29,7 +29,7 @@ extern "C" {
 
 /* Blender file format version. */
 #define BLENDER_FILE_VERSION BLENDER_VERSION
-#define BLENDER_FILE_SUBVERSION 22
+#define BLENDER_FILE_SUBVERSION 23
 
 /* Minimum Blender version that supports reading file written with the current
  * version. Older Blender versions will test this and cancel loading the file, showing a warning to

source/blender/blenloader/intern/versioning_400.cc

@@ -534,6 +534,12 @@ void do_versions_after_linking_400(FileData *fd, Main *bmain)
     }
   }
 
+  if (!MAIN_VERSION_FILE_ATLEAST(bmain, 402, 23)) {
+    /* Shift animation data to accomidate the new Roughness input. */
+    version_node_socket_index_animdata(
+        bmain, NTREE_SHADER, SH_NODE_SUBSURFACE_SCATTERING, 4, 1, 5);
+  }
+
   /**
    * Always bump subversion in BKE_blender_version.h when adding versioning
    * code here, and wrap it inside a MAIN_VERSION_FILE_ATLEAST check.

source/blender/gpu/shaders/material/gpu_shader_material_subsurface_scattering.glsl

@@ -6,6 +6,7 @@ void node_subsurface_scattering(vec4 color,
                                 float scale,
                                 vec3 radius,
                                 float ior,
+                                float roughness,
                                 float anisotropy,
                                 vec3 N,
                                 float weight,
@@ -14,6 +15,7 @@ void node_subsurface_scattering(vec4 color,
 {
   color = max(color, vec4(0.0));
   ior = max(ior, 1e-5);
+  /* roughness = saturate(roughness) */
   N = safe_normalize(N);
 
   ClosureSubsurface sss_data;

source/blender/nodes/shader/nodes/node_shader_subsurface_scattering.cc

@@ -19,6 +19,11 @@ static void node_declare(NodeDeclarationBuilder &b)
   b.add_input<decl::Float>("Scale").default_value(0.05f).min(0.0f).max(1000.0f);
   b.add_input<decl::Vector>("Radius").default_value({1.0f, 0.2f, 0.1f}).min(0.0f).max(100.0f);
   b.add_input<decl::Float>("IOR").default_value(1.4f).min(1.01f).max(3.8f).subtype(PROP_FACTOR);
+  b.add_input<decl::Float>("Roughness")
+      .default_value(1.0f)
+      .min(0.0f)
+      .max(1.0f)
+      .subtype(PROP_FACTOR);
   b.add_input<decl::Float>("Anisotropy")
       .default_value(0.0f)
       .min(0.0f)
@@ -46,8 +51,8 @@ static int node_shader_gpu_subsurface_scattering(GPUMaterial *mat,
                                                  GPUNodeStack *in,
                                                  GPUNodeStack *out)
 {
-  if (!in[5].link) {
-    GPU_link(mat, "world_normals_get", &in[5].link);
+  if (!in[6].link) {
+    GPU_link(mat, "world_normals_get", &in[6].link);
   }
 
   bNodeSocket *socket = (bNodeSocket *)BLI_findlink(&node->runtime->original->inputs, 2);
@@ -70,6 +75,9 @@ static void node_shader_update_subsurface_scattering(bNodeTree *ntree, bNode *no
     if (STR_ELEM(sock->name, "IOR", "Anisotropy")) {
       bke::nodeSetSocketAvailability(ntree, sock, sss_method != SHD_SUBSURFACE_BURLEY);
     }
+    if (STR_ELEM(sock->name, "Roughness")) {
+      bke::nodeSetSocketAvailability(ntree, sock, sss_method == SHD_SUBSURFACE_RANDOM_WALK);
+    }
   }
 }