Cycles: add roughness baking support, using squared roughness convention.

intern/cycles/blender/addon/properties.py

@@ -571,6 +571,7 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
                 ('SHADOW', "Shadow", ""),
                 ('NORMAL', "Normal", ""),
                 ('UV', "UV", ""),
+                ('ROUGHNESS', "Roughness", ""),
                 ('EMIT', "Emit", ""),
                 ('ENVIRONMENT', "Environment", ""),
                 ('DIFFUSE', "Diffuse", ""),

intern/cycles/blender/blender_session.cpp

@@ -252,6 +252,8 @@ static ShaderEvalType get_shader_type(const string& pass_type)
 		return SHADER_EVAL_NORMAL;
 	else if(strcmp(shader_type, "UV")==0)
 		return SHADER_EVAL_UV;
+	else if(strcmp(shader_type, "ROUGHNESS")==0)
+		return SHADER_EVAL_ROUGHNESS;
 	else if(strcmp(shader_type, "DIFFUSE_COLOR")==0)
 		return SHADER_EVAL_DIFFUSE_COLOR;
 	else if(strcmp(shader_type, "GLOSSY_COLOR")==0)

intern/cycles/kernel/kernel_bake.h

@@ -330,15 +330,30 @@ ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input,
 	switch(type) {
 		/* data passes */
 		case SHADER_EVAL_NORMAL:
+		case SHADER_EVAL_ROUGHNESS:
+		case SHADER_EVAL_EMISSION:
 		{
-			float3 N = sd.N;
-			if((sd.flag & SD_HAS_BUMP)) {
-				shader_eval_surface(kg, &sd, &state, 0);
-				N = shader_bsdf_average_normal(kg, &sd);
+			if(type != SHADER_EVAL_NORMAL || (sd.flag & SD_HAS_BUMP)) {
+				int path_flag = (type == SHADER_EVAL_EMISSION) ? PATH_RAY_EMISSION : 0;
+				shader_eval_surface(kg, &sd, &state, path_flag);
 			}
 
-			/* encoding: normal = (2 * color) - 1 */
-			out = N * 0.5f + make_float3(0.5f, 0.5f, 0.5f);
+			if(type == SHADER_EVAL_NORMAL) {
+				float3 N = sd.N;
+				if(sd.flag & SD_HAS_BUMP) {
+					N = shader_bsdf_average_normal(kg, &sd);
+				}
+
+				/* encoding: normal = (2 * color) - 1 */
+				out = N * 0.5f + make_float3(0.5f, 0.5f, 0.5f);
+			}
+			else if(type == SHADER_EVAL_ROUGHNESS) {
+				float roughness = shader_bsdf_average_roughness(&sd);
+				out = make_float3(roughness, roughness, roughness);
+			}
+			else {
+				out = shader_emissive_eval(kg, &sd);
+			}
 			break;
 		}
 		case SHADER_EVAL_UV:
@@ -346,13 +361,6 @@ ccl_device void kernel_bake_evaluate(KernelGlobals *kg, ccl_global uint4 *input,
 			out = primitive_uv(kg, &sd);
 			break;
 		}
-		case SHADER_EVAL_EMISSION:
-		{
-			shader_eval_surface(kg, &sd, &state, PATH_RAY_EMISSION);
-			out = shader_emissive_eval(kg, &sd);
-			break;
-		}
-
 #ifdef __PASSES__
 		/* light passes */
 		case SHADER_EVAL_AO:

intern/cycles/kernel/kernel_shader.h

@@ -763,6 +763,26 @@ ccl_device int shader_bsdf_sample_closure(KernelGlobals *kg, ShaderData *sd,
 	return label;
 }
 
+ccl_device float shader_bsdf_average_roughness(ShaderData *sd)
+{
+	float roughness = 0.0f;
+	float sum_weight = 0.0f;
+
+	for(int i = 0; i < sd->num_closure; i++) {
+		ShaderClosure *sc = &sd->closure[i];
+
+		if(CLOSURE_IS_BSDF(sc->type)) {
+			/* sqrt once to undo the squaring from multiplying roughness on the
+			 * two axes, and once for the squared roughness convention. */
+			float weight = fabsf(average(sc->weight));
+			roughness += weight * sqrtf(safe_sqrtf(bsdf_get_roughness_squared(sc)));
+			sum_weight += weight;
+		}
+	}
+
+	return (sum_weight > 0.0f) ? roughness / sum_weight : 0.0f;
+}
+
 ccl_device void shader_bsdf_blur(KernelGlobals *kg, ShaderData *sd, float roughness)
 {
 	for(int i = 0; i < sd->num_closure; i++) {
@@ -875,7 +895,7 @@ ccl_device float3 shader_bsdf_average_normal(KernelGlobals *kg, ShaderData *sd)
 	for(int i = 0; i < sd->num_closure; i++) {
 		ShaderClosure *sc = &sd->closure[i];
 		if(CLOSURE_IS_BSDF_OR_BSSRDF(sc->type))
-			N += sc->N*average(sc->weight);
+			N += sc->N*fabsf(average(sc->weight));
 	}
 
 	return (is_zero(N))? sd->N : normalize(N);
@@ -892,11 +912,11 @@ ccl_device float3 shader_bsdf_ao(KernelGlobals *kg, ShaderData *sd, float ao_fac
 		if(CLOSURE_IS_BSDF_DIFFUSE(sc->type)) {
 			const DiffuseBsdf *bsdf = (const DiffuseBsdf*)sc;
 			eval += sc->weight*ao_factor;
-			N += bsdf->N*average(sc->weight);
+			N += bsdf->N*fabsf(average(sc->weight));
 		}
 		else if(CLOSURE_IS_AMBIENT_OCCLUSION(sc->type)) {
 			eval += sc->weight;
-			N += sd->N*average(sc->weight);
+			N += sd->N*fabsf(average(sc->weight));
 		}
 	}
 

intern/cycles/kernel/kernel_types.h

@@ -263,6 +263,7 @@ typedef enum ShaderEvalType {
 	/* data passes */
 	SHADER_EVAL_NORMAL,
 	SHADER_EVAL_UV,
+	SHADER_EVAL_ROUGHNESS,
 	SHADER_EVAL_DIFFUSE_COLOR,
 	SHADER_EVAL_GLOSSY_COLOR,
 	SHADER_EVAL_TRANSMISSION_COLOR,

intern/cycles/render/bake.cpp

@@ -247,7 +247,7 @@ void BakeManager::device_free(Device * /*device*/, DeviceScene * /*dscene*/)
 
 int BakeManager::aa_samples(Scene *scene, BakeData *bake_data, ShaderEvalType type)
 {
-	if(type == SHADER_EVAL_UV) {
+	if(type == SHADER_EVAL_UV || type == SHADER_EVAL_ROUGHNESS) {
 		return 1;
 	}
 	else if(type == SHADER_EVAL_NORMAL) {

source/blender/makesdna/DNA_scene_types.h

@@ -251,6 +251,7 @@ typedef enum eScenePassType {
 	SCE_PASS_SUBSURFACE_DIRECT        = (1 << 28),
 	SCE_PASS_SUBSURFACE_INDIRECT      = (1 << 29),
 	SCE_PASS_SUBSURFACE_COLOR         = (1 << 30),
+	SCE_PASS_ROUGHNESS                = (1 << 31),
 } eScenePassType;
 
 #define RE_PASSNAME_COMBINED "Combined"

source/blender/makesrna/intern/rna_render.c

@@ -89,6 +89,7 @@ const EnumPropertyItem rna_enum_bake_pass_type_items[] = {
 	{SCE_PASS_SHADOW, "SHADOW", 0, "Shadow", ""},
 	{SCE_PASS_NORMAL, "NORMAL", 0, "Normal", ""},
 	{SCE_PASS_UV, "UV", 0, "UV", ""},
+	{SCE_PASS_ROUGHNESS, "ROUGHNESS", 0, "ROUGHNESS", ""},
 	{SCE_PASS_EMIT, "EMIT", 0, "Emit", ""},
 	{SCE_PASS_ENVIRONMENT, "ENVIRONMENT", 0, "Environment", ""},
 	{SCE_PASS_DIFFUSE_COLOR, "DIFFUSE", 0, "Diffuse", ""},