Cycles: switch to squared roughness convention for all nodes.

This was already done for the Principled BSDF to be compatible with typical
baked roughness maps in PBR workflows.

11 files changed, 99 insertions, 34 deletions

diff --git a/intern/cycles/blender/addon/version_update.py b/intern/cycles/blender/addon/version_update.py
index 90cecec215d..292f0a1fa90 100644
--- a/intern/cycles/blender/addon/version_update.py
+++ b/intern/cycles/blender/addon/version_update.py
@@ -17,6 +17,7 @@
 # <pep8 compliant>
 
 import bpy
+import math
 
 from bpy.app.handlers import persistent
 
@@ -138,6 +139,56 @@ def displacement_principled_nodes(node):
         if node.subsurface_method != 'RANDOM_WALK':
             node.subsurface_method = 'BURLEY'
 
+def square_roughness_node_insert(material, nodetree, traversed):
+    if nodetree in traversed:
+        return
+    traversed.add(nodetree)
+
+    roughness_node_types = {
+        'ShaderNodeBsdfAnisotropic',
+        'ShaderNodeBsdfGlass',
+        'ShaderNodeBsdfGlossy',
+        'ShaderNodeBsdfRefraction'}
+
+    # Update default values
+    for node in nodetree.nodes:
+        if node.bl_idname == 'ShaderNodeGroup':
+            square_roughness_node_insert(material, node.node_tree, traversed)
+        elif node.bl_idname in roughness_node_types:
+            roughness_input = node.inputs['Roughness']
+            roughness_input.default_value = math.sqrt(max(roughness_input.default_value, 0.0))
+
+    # Gather roughness links to replace
+    roughness_links = []
+    for link in nodetree.links:
+        if link.to_node.bl_idname in roughness_node_types and \
+           link.to_socket.identifier == 'Roughness':
+           roughness_links.append(link)
+
+    # Replace links with sqrt node
+    for link in roughness_links:
+        from_node = link.from_node
+        from_socket = link.from_socket
+        to_node = link.to_node
+        to_socket = link.to_socket
+
+        nodetree.links.remove(link)
+
+        node = nodetree.nodes.new(type='ShaderNodeMath')
+        node.operation = 'POWER'
+        node.location[0] = 0.5 * (from_node.location[0] + to_node.location[0]);
+        node.location[1] = 0.5 * (from_node.location[1] + to_node.location[1]);
+
+        nodetree.links.new(from_socket, node.inputs[0])
+        node.inputs[1].default_value = 0.5
+        nodetree.links.new(node.outputs['Value'], to_socket)
+
+def square_roughness_nodes_insert():
+    traversed = set()
+    for material in bpy.data.materials:
+        if check_is_new_shading_material(material):
+            square_roughness_node_insert(material, material.node_tree, traversed)
+
 
 def mapping_node_order_flip(node):
     """
@@ -376,3 +427,7 @@ def do_versions(self):
                 cmat.displacement_method = 'BUMP'
 
         foreach_cycles_node(displacement_principled_nodes)
+
+    if bpy.data.version <= (2, 79, 3):
+        # Switch to squared roughness convention
+        square_roughness_nodes_insert()
diff --git a/intern/cycles/kernel/shaders/node_anisotropic_bsdf.osl b/intern/cycles/kernel/shaders/node_anisotropic_bsdf.osl
index bef6d7e8809..21e28ece65d 100644
--- a/intern/cycles/kernel/shaders/node_anisotropic_bsdf.osl
+++ b/intern/cycles/kernel/shaders/node_anisotropic_bsdf.osl
@@ -33,27 +33,28 @@ shader node_anisotropic_bsdf(
 		T = rotate(T, Rotation * M_2PI, point(0.0, 0.0, 0.0), Normal);
 
 	/* compute roughness */
-	float RoughnessU, RoughnessV;
+	float roughness = Roughness * Roughness;
+	float roughness_u, roughness_v;
 	float aniso = clamp(Anisotropy, -0.99, 0.99);
 
 	if (aniso < 0.0) {
-		RoughnessU = Roughness / (1.0 + aniso);
-		RoughnessV = Roughness * (1.0 + aniso);
+		roughness_u = roughness / (1.0 + aniso);
+		roughness_v = roughness * (1.0 + aniso);
 	}
 	else {
-		RoughnessU = Roughness * (1.0 - aniso);
-		RoughnessV = Roughness / (1.0 - aniso);
+		roughness_u = roughness * (1.0 - aniso);
+		roughness_v = roughness / (1.0 - aniso);
 	}
 
 	if (distribution == "sharp")
 		BSDF = Color * reflection(Normal);
 	else if (distribution == "beckmann")
-		BSDF = Color * microfacet_beckmann_aniso(Normal, T, RoughnessU, RoughnessV);
+		BSDF = Color * microfacet_beckmann_aniso(Normal, T, roughness_u, roughness_v);
 	else if (distribution == "GGX")
-		BSDF = Color * microfacet_ggx_aniso(Normal, T, RoughnessU, RoughnessV);
+		BSDF = Color * microfacet_ggx_aniso(Normal, T, roughness_u, roughness_v);
 	else if (distribution == "Multiscatter GGX")
-		BSDF = Color * microfacet_multi_ggx_aniso(Normal, T, RoughnessU, RoughnessV, Color);
+		BSDF = Color * microfacet_multi_ggx_aniso(Normal, T, roughness_u, roughness_v, Color);
 	else
-		BSDF = Color * ashikhmin_shirley(Normal, T, RoughnessU, RoughnessV);
+		BSDF = Color * ashikhmin_shirley(Normal, T, roughness_u, roughness_v);
 }
 
diff --git a/intern/cycles/kernel/shaders/node_glass_bsdf.osl b/intern/cycles/kernel/shaders/node_glass_bsdf.osl
index a9723a8300a..2e713861c58 100644
--- a/intern/cycles/kernel/shaders/node_glass_bsdf.osl
+++ b/intern/cycles/kernel/shaders/node_glass_bsdf.osl
@@ -29,16 +29,17 @@ shader node_glass_bsdf(
 	float eta = backfacing() ? 1.0 / f : f;
 	float cosi = dot(I, Normal);
 	float Fr = fresnel_dielectric_cos(cosi, eta);
+	float roughness = Roughness * Roughness;
 
 	if (distribution == "sharp")
 		BSDF = Color * (Fr * reflection(Normal) + (1.0 - Fr) * refraction(Normal, eta));
 	else if (distribution == "beckmann")
-		BSDF = Color * (Fr * microfacet_beckmann(Normal, Roughness) +
-		                (1.0 - Fr) * microfacet_beckmann_refraction(Normal, Roughness, eta));
+		BSDF = Color * (Fr * microfacet_beckmann(Normal, roughness) +
+		                (1.0 - Fr) * microfacet_beckmann_refraction(Normal, roughness, eta));
 	else if (distribution == "Multiscatter GGX")
-		BSDF = Color * microfacet_multi_ggx_glass(Normal, Roughness, eta, Color);
+		BSDF = Color * microfacet_multi_ggx_glass(Normal, roughness, eta, Color);
 	else if (distribution == "GGX")
-		BSDF = Color * (Fr * microfacet_ggx(Normal, Roughness) +
-		                (1.0 - Fr) * microfacet_ggx_refraction(Normal, Roughness, eta));
+		BSDF = Color * (Fr * microfacet_ggx(Normal, roughness) +
+		                (1.0 - Fr) * microfacet_ggx_refraction(Normal, roughness, eta));
 }
 
diff --git a/intern/cycles/kernel/shaders/node_glossy_bsdf.osl b/intern/cycles/kernel/shaders/node_glossy_bsdf.osl
index f4ea7e7dc6a..7415211b56d 100644
--- a/intern/cycles/kernel/shaders/node_glossy_bsdf.osl
+++ b/intern/cycles/kernel/shaders/node_glossy_bsdf.osl
@@ -24,16 +24,18 @@ shader node_glossy_bsdf(
 	normal Normal = N,
 	output closure color BSDF = 0)
 {
+	float roughness = Roughness * Roughness;
+
 	if (distribution == "sharp")
 		BSDF = Color * reflection(Normal);
 	else if (distribution == "beckmann")
-		BSDF = Color * microfacet_beckmann(Normal, Roughness);
+		BSDF = Color * microfacet_beckmann(Normal, roughness);
 	else if (distribution == "GGX")
-		BSDF = Color * microfacet_ggx(Normal, Roughness);
+		BSDF = Color * microfacet_ggx(Normal, roughness);
 	else if (distribution == "Multiscatter GGX")
-		BSDF = Color * microfacet_multi_ggx(Normal, Roughness, Color);
+		BSDF = Color * microfacet_multi_ggx(Normal, roughness, Color);
 	else
-		BSDF = Color * ashikhmin_shirley(Normal, vector(0, 0, 0), Roughness, Roughness);
+		BSDF = Color * ashikhmin_shirley(Normal, vector(0, 0, 0), roughness, roughness);
 
 }
 
diff --git a/intern/cycles/kernel/shaders/node_refraction_bsdf.osl b/intern/cycles/kernel/shaders/node_refraction_bsdf.osl
index 828becf1818..eaab7282243 100644
--- a/intern/cycles/kernel/shaders/node_refraction_bsdf.osl
+++ b/intern/cycles/kernel/shaders/node_refraction_bsdf.osl
@@ -26,12 +26,13 @@ shader node_refraction_bsdf(
 {
 	float f = max(IOR, 1e-5);
 	float eta = backfacing() ? 1.0 / f : f;
+	float roughness = Roughness * Roughness;
 
 	if (distribution == "sharp")
 		BSDF = Color * refraction(Normal, eta);
 	else if (distribution == "beckmann")
-		BSDF = Color * microfacet_beckmann_refraction(Normal, Roughness, eta);
+		BSDF = Color * microfacet_beckmann_refraction(Normal, roughness, eta);
 	else if (distribution == "GGX")
-		BSDF = Color * microfacet_ggx_refraction(Normal, Roughness, eta);
+		BSDF = Color * microfacet_ggx_refraction(Normal, roughness, eta);
 }
 
diff --git a/intern/cycles/kernel/svm/svm_closure.h b/intern/cycles/kernel/svm/svm_closure.h
index a54095ed127..886a1333fa3 100644
--- a/intern/cycles/kernel/svm/svm_closure.h
+++ b/intern/cycles/kernel/svm/svm_closure.h
@@ -468,10 +468,12 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *
 				break;
 			}
 
+			float roughness = sqr(param1);
+
 			bsdf->N = N;
 			bsdf->T = make_float3(0.0f, 0.0f, 0.0f);
-			bsdf->alpha_x = param1;
-			bsdf->alpha_y = param1;
+			bsdf->alpha_x = roughness;
+			bsdf->alpha_y = roughness;
 			bsdf->ior = 0.0f;
 			bsdf->extra = NULL;
 
@@ -525,8 +527,9 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *
 					sd->flag |= bsdf_refraction_setup(bsdf);
 				}
 				else {
-					bsdf->alpha_x = param1;
-					bsdf->alpha_y = param1;
+					float roughness = sqr(param1);
+					bsdf->alpha_x = roughness;
+					bsdf->alpha_y = roughness;
 					bsdf->ior = eta;
 
 					if(type == CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID)
@@ -557,7 +560,7 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *
 			/* fresnel */
 			float cosNO = dot(N, sd->I);
 			float fresnel = fresnel_dielectric_cos(cosNO, eta);
-			float roughness = param1;
+			float roughness = sqr(param1);
 
 			/* reflection */
 #ifdef __CAUSTICS_TRICKS__
@@ -611,8 +614,9 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *
 			bsdf->extra = extra;
 			bsdf->T = make_float3(0.0f, 0.0f, 0.0f);
 
-			bsdf->alpha_x = param1;
-			bsdf->alpha_y = param1;
+			float roughness = sqr(param1);
+			bsdf->alpha_x = roughness;
+			bsdf->alpha_y = roughness;
 			float eta = fmaxf(param2, 1e-5f);
 			bsdf->ior = (sd->flag & SD_BACKFACING)? 1.0f/eta: eta;
 
@@ -648,7 +652,7 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *
 					bsdf->T = rotate_around_axis(bsdf->T, bsdf->N, rotation * M_2PI_F);
 
 				/* compute roughness */
-				float roughness = param1;
+				float roughness = sqr(param1);
 				float anisotropy = clamp(param2, -0.99f, 0.99f);
 
 				if(anisotropy < 0.0f) {
diff --git a/intern/cycles/render/nodes.cpp b/intern/cycles/render/nodes.cpp
index f117962a2ea..e36a75f59b1 100644
--- a/intern/cycles/render/nodes.cpp
+++ b/intern/cycles/render/nodes.cpp
@@ -1858,7 +1858,7 @@ NODE_DEFINE(AnisotropicBsdfNode)
 
 	SOCKET_IN_VECTOR(tangent, "Tangent", make_float3(0.0f, 0.0f, 0.0f), SocketType::LINK_TANGENT);
 
-	SOCKET_IN_FLOAT(roughness, "Roughness", 0.2f);
+	SOCKET_IN_FLOAT(roughness, "Roughness", 0.5f);
 	SOCKET_IN_FLOAT(anisotropy, "Anisotropy", 0.5f);
 	SOCKET_IN_FLOAT(rotation, "Rotation", 0.0f);
 
@@ -1918,7 +1918,7 @@ NODE_DEFINE(GlossyBsdfNode)
 	distribution_enum.insert("ashikhmin_shirley", CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ID);
 	distribution_enum.insert("Multiscatter GGX", CLOSURE_BSDF_MICROFACET_MULTI_GGX_ID);
 	SOCKET_ENUM(distribution, "Distribution", distribution_enum, CLOSURE_BSDF_MICROFACET_GGX_ID);
-	SOCKET_IN_FLOAT(roughness, "Roughness", 0.2f);
+	SOCKET_IN_FLOAT(roughness, "Roughness", 0.5f);
 
 	SOCKET_OUT_CLOSURE(BSDF, "BSDF");
 
diff --git a/source/blender/blenkernel/BKE_blender_version.h b/source/blender/blenkernel/BKE_blender_version.h
index 6cd93e19e95..b5d906b2968 100644
--- a/source/blender/blenkernel/BKE_blender_version.h
+++ b/source/blender/blenkernel/BKE_blender_version.h
@@ -28,7 +28,7 @@
  * and keep comment above the defines.
  * Use STRINGIFY() rather than defining with quotes */
 #define BLENDER_VERSION         279
-#define BLENDER_SUBVERSION      3
+#define BLENDER_SUBVERSION      4
 /* Several breakages with 270, e.g. constraint deg vs rad */
 #define BLENDER_MINVERSION      270
 #define BLENDER_MINSUBVERSION   6
diff --git a/source/blender/gpu/shaders/gpu_shader_material.glsl b/source/blender/gpu/shaders/gpu_shader_material.glsl
index 1f5ffbdcc7e..a0ca719e207 100644
--- a/source/blender/gpu/shaders/gpu_shader_material.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_material.glsl
@@ -2599,7 +2599,8 @@ void node_bsdf_glossy(vec4 color, float roughness, vec3 N, out vec4 result)
 		vec3 light_specular = gl_LightSource[i].specular.rgb;
 
 		/* we mix in some diffuse so low roughness still shows up */
-		float bsdf = 0.5 * pow(max(dot(N, H), 0.0), 1.0 / roughness);
+		float r2 = roughness * roughness;
+		float bsdf = 0.5 * pow(max(dot(N, H), 0.0), 1.0 / r2);
 		bsdf += 0.5 * max(dot(N, light_position), 0.0);
 		L += light_specular * bsdf;
 	}
diff --git a/source/blender/nodes/shader/nodes/node_shader_bsdf_anisotropic.c b/source/blender/nodes/shader/nodes/node_shader_bsdf_anisotropic.c
index 01ca0bd6512..6410441797a 100644
--- a/source/blender/nodes/shader/nodes/node_shader_bsdf_anisotropic.c
+++ b/source/blender/nodes/shader/nodes/node_shader_bsdf_anisotropic.c
@@ -31,7 +31,7 @@
 
 static bNodeSocketTemplate sh_node_bsdf_anisotropic_in[] = {
 	{	SOCK_RGBA, 1, N_("Color"),			0.8f, 0.8f, 0.8f, 1.0f, 0.0f, 1.0f},
-	{	SOCK_FLOAT, 1, N_("Roughness"),	    0.2f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, PROP_FACTOR},
+	{	SOCK_FLOAT, 1, N_("Roughness"),	    0.5f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, PROP_FACTOR},
 	{	SOCK_FLOAT, 1, N_("Anisotropy"),	0.5f, 0.0f, 0.0f, 0.0f, -1.0f, 1.0f},
 	{	SOCK_FLOAT, 1, N_("Rotation"),		0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, PROP_FACTOR},
 	{	SOCK_VECTOR, 1, N_("Normal"),		0.0f, 0.0f, 0.0f, 1.0f, -1.0f, 1.0f, PROP_NONE, SOCK_HIDE_VALUE},
diff --git a/source/blender/nodes/shader/nodes/node_shader_bsdf_glossy.c b/source/blender/nodes/shader/nodes/node_shader_bsdf_glossy.c
index 7e1bc971c73..c13fd89d6e5 100644
--- a/source/blender/nodes/shader/nodes/node_shader_bsdf_glossy.c
+++ b/source/blender/nodes/shader/nodes/node_shader_bsdf_glossy.c
@@ -31,7 +31,7 @@
 
 static bNodeSocketTemplate sh_node_bsdf_glossy_in[] = {
 	{	SOCK_RGBA,  1, N_("Color"),		0.8f, 0.8f, 0.8f, 1.0f, 0.0f, 1.0f},
-	{	SOCK_FLOAT, 1, N_("Roughness"),	0.2f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, PROP_FACTOR},
+	{	SOCK_FLOAT, 1, N_("Roughness"),	0.5f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, PROP_FACTOR},
 	{	SOCK_VECTOR, 1, N_("Normal"),	0.0f, 0.0f, 0.0f, 1.0f, -1.0f, 1.0f, PROP_NONE, SOCK_HIDE_VALUE},
 	{	-1, 0, ""	}
 };