[Bf-blender-cvs] [94b99949eb2] master: Fix T54202: Cycles crash rendering empty mesh volume after recent optimization.

[Brecht Van Lommel]

Commit: 94b99949eb20d630e222642a7e7db5ea4d43ef12
Author: Brecht Van Lommel
Date:   Fri Mar 2 22:38:59 2018 +0100
Branches: master
https://developer.blender.org/rB94b99949eb20d630e222642a7e7db5ea4d43ef12

Fix T54202: Cycles crash rendering empty mesh volume after recent optimization.

===================================================================

M	intern/cycles/render/mesh.cpp
M	intern/cycles/render/mesh_volume.cpp

===================================================================

diff --git a/intern/cycles/render/mesh.cpp b/intern/cycles/render/mesh.cpp
index 23b855acdc9..47d24970949 100644
--- a/intern/cycles/render/mesh.cpp
+++ b/intern/cycles/render/mesh.cpp
@@ -561,8 +561,9 @@ void Mesh::clear(bool preserve_voxel_data)
 	subd_attributes.clear();
 	attributes.clear(preserve_voxel_data);
 
+	used_shaders.clear();
+
 	if(!preserve_voxel_data) {
-		used_shaders.clear();
 		geometry_flags = GEOMETRY_NONE;
 	}
 
diff --git a/intern/cycles/render/mesh_volume.cpp b/intern/cycles/render/mesh_volume.cpp
index be43154fd93..f2347c79610 100644
--- a/intern/cycles/render/mesh_volume.cpp
+++ b/intern/cycles/render/mesh_volume.cpp
@@ -393,9 +393,6 @@ void VolumeMeshBuilder::convert_quads_to_tris(const vector<QuadData> &quads,
 
 /* ************************************************************************** */
 
-/* For debugging: render the created mesh using the default diffuse shader. */
-//#define RENDER_DIFFUSE
-
 struct VoxelAttributeGrid {
 	float *data;
 	int channels;
@@ -443,6 +440,8 @@ void MeshManager::create_volume_mesh(Scene *scene,
 		return;
 	}
 
+	/* Compute padding. */
+	Shader *volume_shader = NULL;
 	int pad_size = 0;
 
 	foreach(Shader *shader, mesh->used_shaders) {
@@ -450,12 +449,20 @@ void MeshManager::create_volume_mesh(Scene *scene,
 			continue;
 		}
 
+		volume_shader = shader;
+
 		if(shader->volume_interpolation_method == VOLUME_INTERPOLATION_LINEAR) {
 			pad_size = max(1, pad_size);
 		}
 		else if(shader->volume_interpolation_method == VOLUME_INTERPOLATION_CUBIC) {
 			pad_size = max(2, pad_size);
 		}
+
+		break;
+	}
+
+	if(!volume_shader) {
+		return;
 	}
 
 	/* Compute start point and cell size from transform. */
@@ -477,6 +484,7 @@ void MeshManager::create_volume_mesh(Scene *scene,
 	volume_params.cell_size = cell_size;
 	volume_params.pad_size = pad_size;
 
+	/* Build bounding mesh around non-empty volume cells. */
 	VolumeMeshBuilder builder(&volume_params);
 	const float isovalue = mesh->volume_isovalue;
 
@@ -540,26 +548,22 @@ void MeshManager::create_volume_mesh(Scene *scene,
 		}
 	}
 
+	/* Create mesh. */
 	vector<float3> vertices;
 	vector<int> indices;
 	vector<float3> face_normals;
 	builder.create_mesh(vertices, indices, face_normals);
 
-#ifdef RENDER_DIFFUSE
-	int shader = mesh->used_shaders[0]->id;
-#else
-	int shader = mesh->shader[0];
-#endif
-
 	mesh->clear(true);
 	mesh->reserve_mesh(vertices.size(), indices.size()/3);
+	mesh->used_shaders.push_back(volume_shader);
 
 	for(size_t i = 0; i < vertices.size(); ++i) {
 		mesh->add_vertex(vertices[i]);
 	}
 
 	for(size_t i = 0; i < indices.size(); i += 3) {
-		mesh->add_triangle(indices[i], indices[i + 1], indices[i + 2], shader, false);
+		mesh->add_triangle(indices[i], indices[i + 1], indices[i + 2], 0, false);
 	}
 
 	Attribute *attr_fN = mesh->attributes.add(ATTR_STD_FACE_NORMAL);
@@ -569,6 +573,7 @@ void MeshManager::create_volume_mesh(Scene *scene,
 		fN[i] = face_normals[i];
 	}
 
+	/* Print stats. */
 	VLOG(1) << "Memory usage volume mesh: "
 			<< ((vertices.size() + face_normals.size())*sizeof(float3) + indices.size()*sizeof(int))/(1024.0*1024.0)
 			<< "Mb.";