Cycles microdisplacement: Move displacement options from mesh to material settings

Displacement is now a per material setting, which means old files will have to
be updated if they had used displacement. Cool side effect of this change is
material previews now show displacement.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D2140

1 files changed, 146 insertions, 14 deletions

diff --git a/intern/cycles/render/mesh_displace.cpp b/intern/cycles/render/mesh_displace.cpp
index 95f46ff02a2..ef9cfedd412 100644
--- a/intern/cycles/render/mesh_displace.cpp
+++ b/intern/cycles/render/mesh_displace.cpp
@@ -26,19 +26,27 @@
 
 CCL_NAMESPACE_BEGIN
 
+static float3 compute_face_normal(const Mesh::Triangle& t, float3 *verts)
+{
+	float3 v0 = verts[t.v[0]];
+	float3 v1 = verts[t.v[1]];
+	float3 v2 = verts[t.v[2]];
+
+	float3 norm = cross(v1 - v0, v2 - v0);
+	float normlen = len(norm);
+
+	if(normlen == 0.0f)
+		return make_float3(1.0f, 0.0f, 0.0f);
+
+	return norm / normlen;
+}
+
 bool MeshManager::displace(Device *device, DeviceScene *dscene, Scene *scene, Mesh *mesh, Progress& progress)
 {
 	/* verify if we have a displacement shader */
-	bool has_displacement = false;
-
-	if(mesh->displacement_method != Mesh::DISPLACE_BUMP) {
-		foreach(Shader *shader, mesh->used_shaders)
-			if(shader->has_displacement)
-				has_displacement = true;
-	}
-	
-	if(!has_displacement)
+	if(!mesh->has_true_displacement()) {
 		return false;
+	}
 
 	string msg = string_printf("Computing Displacement %s", mesh->name.c_str());
 	progress.set_status("Updating Mesh", msg);
@@ -67,8 +75,9 @@ bool MeshManager::displace(Device *device, DeviceScene *dscene, Scene *scene, Me
 		Shader *shader = (shader_index < mesh->used_shaders.size()) ?
 			mesh->used_shaders[shader_index] : scene->default_surface;
 
-		if(!shader->has_displacement)
+		if(!shader->has_displacement || shader->displacement_method == DISPLACE_BUMP) {
 			continue;
+		}
 
 		for(int j = 0; j < 3; j++) {
 			if(done[t.v[j]])
@@ -153,8 +162,9 @@ bool MeshManager::displace(Device *device, DeviceScene *dscene, Scene *scene, Me
 		Shader *shader = (shader_index < mesh->used_shaders.size()) ?
 			mesh->used_shaders[shader_index] : scene->default_surface;
 
-		if(!shader->has_displacement)
+		if(!shader->has_displacement || shader->displacement_method == DISPLACE_BUMP) {
 			continue;
+		}
 
 		for(int j = 0; j < 3; j++) {
 			if(!done[t.v[j]]) {
@@ -178,9 +188,131 @@ bool MeshManager::displace(Device *device, DeviceScene *dscene, Scene *scene, Me
 	mesh->attributes.remove(ATTR_STD_FACE_NORMAL);
 	mesh->add_face_normals();
 
-	if(mesh->displacement_method == Mesh::DISPLACE_TRUE) {
-		mesh->attributes.remove(ATTR_STD_VERTEX_NORMAL);
-		mesh->add_vertex_normals();
+	bool need_recompute_vertex_normals = false;
+
+	foreach(Shader *shader, mesh->used_shaders) {
+		if(shader->has_displacement && shader->displacement_method == DISPLACE_TRUE) {
+			need_recompute_vertex_normals = true;
+			break;
+		}
+	}
+
+	if(need_recompute_vertex_normals) {
+		bool flip = mesh->transform_negative_scaled;
+		vector<bool> tri_has_true_disp(num_triangles, false);
+
+		for(size_t i = 0; i < num_triangles; i++) {
+			int shader_index = mesh->shader[i];
+			Shader *shader = (shader_index < mesh->used_shaders.size()) ?
+				mesh->used_shaders[shader_index] : scene->default_surface;
+
+			tri_has_true_disp[i] = shader->has_displacement && shader->displacement_method == DISPLACE_TRUE;
+		}
+
+		/* static vertex normals */
+
+		/* get attributes */
+		Attribute *attr_fN = mesh->attributes.find(ATTR_STD_FACE_NORMAL);
+		Attribute *attr_vN = mesh->attributes.find(ATTR_STD_VERTEX_NORMAL);
+
+		float3 *fN = attr_fN->data_float3();
+		float3 *vN = attr_vN->data_float3();
+
+		/* compute vertex normals */
+
+		/* zero vertex normals on triangles with true displacement */
+		for(size_t i = 0; i < num_triangles; i++) {
+			if(tri_has_true_disp[i]) {
+				for(size_t j = 0; j < 3; j++) {
+					vN[mesh->get_triangle(i).v[j]] = make_float3(0.0f, 0.0f, 0.0f);
+				}
+			}
+		}
+
+		/* add face normals to vertex normals */
+		for(size_t i = 0; i < num_triangles; i++) {
+			if(tri_has_true_disp[i]) {
+				for(size_t j = 0; j < 3; j++) {
+					vN[mesh->get_triangle(i).v[j]] += fN[i];
+				}
+			}
+		}
+
+		/* normalize vertex normals */
+		done.clear();
+		done.resize(num_verts, false);
+
+		for(size_t i = 0; i < num_triangles; i++) {
+			if(tri_has_true_disp[i]) {
+				for(size_t j = 0; j < 3; j++) {
+					int vert = mesh->get_triangle(i).v[j];
+
+					if(done[vert]) {
+						continue;
+					}
+
+					vN[vert] = normalize(vN[vert]);
+					if(flip)
+						vN[vert] = -vN[vert];
+
+					done[vert] = true;
+				}
+			}
+		}
+
+		/* motion vertex normals */
+		Attribute *attr_mP = mesh->attributes.find(ATTR_STD_MOTION_VERTEX_POSITION);
+		Attribute *attr_mN = mesh->attributes.find(ATTR_STD_MOTION_VERTEX_NORMAL);
+
+		if(mesh->has_motion_blur() && attr_mP && attr_mN) {
+			for(int step = 0; step < mesh->motion_steps - 1; step++) {
+				float3 *mP = attr_mP->data_float3() + step*mesh->verts.size();
+				float3 *mN = attr_mN->data_float3() + step*mesh->verts.size();
+
+				/* compute */
+
+				/* zero vertex normals on triangles with true displacement */
+				for(size_t i = 0; i < num_triangles; i++) {
+					if(tri_has_true_disp[i]) {
+						for(size_t j = 0; j < 3; j++) {
+							mN[mesh->get_triangle(i).v[j]] = make_float3(0.0f, 0.0f, 0.0f);
+						}
+					}
+				}
+
+				/* add face normals to vertex normals */
+				for(size_t i = 0; i < num_triangles; i++) {
+					if(tri_has_true_disp[i]) {
+						for(size_t j = 0; j < 3; j++) {
+							float3 fN = compute_face_normal(mesh->get_triangle(i), mP);
+							mN[mesh->get_triangle(i).v[j]] += fN;
+						}
+					}
+				}
+
+				/* normalize vertex normals */
+				done.clear();
+				done.resize(num_verts, false);
+
+				for(size_t i = 0; i < num_triangles; i++) {
+					if(tri_has_true_disp[i]) {
+						for(size_t j = 0; j < 3; j++) {
+							int vert = mesh->get_triangle(i).v[j];
+
+							if(done[vert]) {
+								continue;
+							}
+
+							mN[vert] = normalize(mN[vert]);
+							if(flip)
+								mN[vert] = -mN[vert];
+
+							done[vert] = true;
+						}
+					}
+				}
+			}
+		}
 	}
 
 	return true;