MeshLibrary export improvements

- From now materials assigned to the MeshInstance (not the Mesh) get exported
  into the MeshLibrary when such materials exist. This enables workflows where
  the MeshLibrary is exported from an imported scene (e.g. GLTF) where the
  materials assigned to the Mesh (not the MeshInstance) get overwritten on
  re-import, thus can't use editor set materials in the exported MeshLibrary
  unless they are assigned to the MeshInstance whose materials get saved with
  the inherited scene thus persist across re-imports.
- When appending to an existing MeshLibrary only generate previews for newly
  added or modified meshes.
- During preview generation transform camera and lights instead of the mesh
  and use the source MeshInstance's transform for the mesh to avoid weird
  previews being generated for meshes with a position dependent material
  (e.g. when using triplanar mapping).
- Adjust the camera angle and light directions used in mesh preview generation
  for better results.

3 files changed, 50 insertions, 25 deletions

diff --git a/editor/editor_plugin.cpp b/editor/editor_plugin.cpp
index c2493729a3..ce7d07117c 100644
--- a/editor/editor_plugin.cpp
+++ b/editor/editor_plugin.cpp
@@ -48,7 +48,7 @@ Array EditorInterface::_make_mesh_previews(const Array &p_meshes, int p_preview_
 		meshes.push_back(p_meshes[i]);
 	}
 
-	Vector<Ref<Texture> > textures = make_mesh_previews(meshes, p_preview_size);
+	Vector<Ref<Texture> > textures = make_mesh_previews(meshes, NULL, p_preview_size);
 	Array ret;
 	for (int i = 0; i < textures.size(); i++) {
 		ret.push_back(textures[i]);
@@ -57,7 +57,7 @@ Array EditorInterface::_make_mesh_previews(const Array &p_meshes, int p_preview_
 	return ret;
 }
 
-Vector<Ref<Texture> > EditorInterface::make_mesh_previews(const Vector<Ref<Mesh> > &p_meshes, int p_preview_size) {
+Vector<Ref<Texture> > EditorInterface::make_mesh_previews(const Vector<Ref<Mesh> > &p_meshes, Vector<Transform> *p_transforms, int p_preview_size) {
 
 	int size = p_preview_size;
 
@@ -74,25 +74,14 @@ Vector<Ref<Texture> > EditorInterface::make_mesh_previews(const Vector<Ref<Mesh>
 
 	RID camera = VS::get_singleton()->camera_create();
 	VS::get_singleton()->viewport_attach_camera(viewport, camera);
-	VS::get_singleton()->camera_set_transform(camera, Transform(Basis(), Vector3(0, 0, 3)));
-	//VS::get_singleton()->camera_set_perspective(camera,45,0.1,10);
-	VS::get_singleton()->camera_set_orthogonal(camera, 1.0, 0.01, 1000.0);
 
 	RID light = VS::get_singleton()->directional_light_create();
 	RID light_instance = VS::get_singleton()->instance_create2(light, scenario);
-	VS::get_singleton()->instance_set_transform(light_instance, Transform().looking_at(Vector3(-1, -1, -1), Vector3(0, 1, 0)));
 
 	RID light2 = VS::get_singleton()->directional_light_create();
 	VS::get_singleton()->light_set_color(light2, Color(0.7, 0.7, 0.7));
-	//VS::get_singleton()->light_set_color(light2, VS::LIGHT_COLOR_SPECULAR, Color(0.0, 0.0, 0.0));
 	RID light_instance2 = VS::get_singleton()->instance_create2(light2, scenario);
 
-	VS::get_singleton()->instance_set_transform(light_instance2, Transform().looking_at(Vector3(0, 1, 0), Vector3(0, 0, 1)));
-
-	//sphere = VS::get_singleton()->mesh_create();
-	RID mesh_instance = VS::get_singleton()->instance_create();
-	VS::get_singleton()->instance_set_scenario(mesh_instance, scenario);
-
 	EditorProgress ep("mlib", TTR("Creating Mesh Previews"), p_meshes.size());
 
 	Vector<Ref<Texture> > textures;
@@ -104,25 +93,38 @@ Vector<Ref<Texture> > EditorInterface::make_mesh_previews(const Vector<Ref<Mesh>
 			textures.push_back(Ref<Texture>());
 			continue;
 		}
+
+		Transform mesh_xform;
+		if (p_transforms != NULL) {
+			mesh_xform = (*p_transforms)[i];
+		}
+
+		RID inst = VS::get_singleton()->instance_create2(mesh->get_rid(), scenario);
+		VS::get_singleton()->instance_set_transform(inst, mesh_xform);
+
 		AABB aabb = mesh->get_aabb();
 		Vector3 ofs = aabb.position + aabb.size * 0.5;
 		aabb.position -= ofs;
 		Transform xform;
-		xform.basis = Basis().rotated(Vector3(0, 1, 0), -Math_PI * 0.25);
-		xform.basis = Basis().rotated(Vector3(1, 0, 0), Math_PI * 0.25) * xform.basis;
+		xform.basis = Basis().rotated(Vector3(0, 1, 0), -Math_PI / 6);
+		xform.basis = Basis().rotated(Vector3(1, 0, 0), Math_PI / 6) * xform.basis;
 		AABB rot_aabb = xform.xform(aabb);
 		float m = MAX(rot_aabb.size.x, rot_aabb.size.y) * 0.5;
 		if (m == 0) {
 			textures.push_back(Ref<Texture>());
 			continue;
 		}
-		m = 1.0 / m;
-		m *= 0.5;
-		xform.basis.scale(Vector3(m, m, m));
 		xform.origin = -xform.basis.xform(ofs); //-ofs*m;
 		xform.origin.z -= rot_aabb.size.z * 2;
-		RID inst = VS::get_singleton()->instance_create2(mesh->get_rid(), scenario);
-		VS::get_singleton()->instance_set_transform(inst, xform);
+		xform.invert();
+		xform = mesh_xform * xform;
+
+		VS::get_singleton()->camera_set_transform(camera, xform * Transform(Basis(), Vector3(0, 0, 3)));
+		VS::get_singleton()->camera_set_orthogonal(camera, m * 2, 0.01, 1000.0);
+
+		VS::get_singleton()->instance_set_transform(light_instance, xform * Transform().looking_at(Vector3(-2, -1, -1), Vector3(0, 1, 0)));
+		VS::get_singleton()->instance_set_transform(light_instance2, xform * Transform().looking_at(Vector3(+1, -1, -2), Vector3(0, 1, 0)));
+
 		ep.step(TTR("Thumbnail..."), i);
 		Main::iteration();
 		Main::iteration();
@@ -136,7 +138,6 @@ Vector<Ref<Texture> > EditorInterface::make_mesh_previews(const Vector<Ref<Mesh>
 		textures.push_back(it);
 	}
 
-	VS::get_singleton()->free(mesh_instance);
 	VS::get_singleton()->free(viewport);
 	VS::get_singleton()->free(light);
 	VS::get_singleton()->free(light_instance);
diff --git a/editor/editor_plugin.h b/editor/editor_plugin.h
index 3e41bb5612..52fe849eab 100644
--- a/editor/editor_plugin.h
+++ b/editor/editor_plugin.h
@@ -98,7 +98,7 @@ public:
 	Error save_scene();
 	void save_scene_as(const String &p_scene, bool p_with_preview = true);
 
-	Vector<Ref<Texture> > make_mesh_previews(const Vector<Ref<Mesh> > &p_meshes, int p_preview_size);
+	Vector<Ref<Texture> > make_mesh_previews(const Vector<Ref<Mesh> > &p_meshes, Vector<Transform> *p_trnasforms, int p_preview_size);
 
 	EditorInterface();
 };
diff --git a/editor/plugins/mesh_library_editor_plugin.cpp b/editor/plugins/mesh_library_editor_plugin.cpp
index aedac7b45d..2622d14ade 100644
--- a/editor/plugins/mesh_library_editor_plugin.cpp
+++ b/editor/plugins/mesh_library_editor_plugin.cpp
@@ -70,6 +70,8 @@ void MeshLibraryEditor::_import_scene(Node *p_scene, Ref<MeshLibrary> p_library,
 	if (!p_merge)
 		p_library->clear();
 
+	Map<int, MeshInstance *> mesh_instances;
+
 	for (int i = 0; i < p_scene->get_child_count(); i++) {
 
 		Node *child = p_scene->get_child(i);
@@ -90,6 +92,15 @@ void MeshLibraryEditor::_import_scene(Node *p_scene, Ref<MeshLibrary> p_library,
 		if (mesh.is_null())
 			continue;
 
+		mesh = mesh->duplicate();
+		for (int j = 0; j < mesh->get_surface_count(); ++j) {
+			Ref<Material> mat = mi->get_surface_material(j);
+
+			if (mat.is_valid()) {
+				mesh->surface_set_material(j, mat);
+			}
+		}
+
 		int id = p_library->find_item_by_name(mi->get_name());
 		if (id < 0) {
 
@@ -99,6 +110,7 @@ void MeshLibraryEditor::_import_scene(Node *p_scene, Ref<MeshLibrary> p_library,
 		}
 
 		p_library->set_item_mesh(id, mesh);
+		mesh_instances[id] = mi;
 
 		Vector<MeshLibrary::ShapeData> collisions;
 
@@ -155,14 +167,26 @@ void MeshLibraryEditor::_import_scene(Node *p_scene, Ref<MeshLibrary> p_library,
 	if (1) {
 
 		Vector<Ref<Mesh> > meshes;
+		Vector<Transform> transforms;
 		Vector<int> ids = p_library->get_item_list();
 		for (int i = 0; i < ids.size(); i++) {
-			meshes.push_back(p_library->get_item_mesh(ids[i]));
+
+			if (mesh_instances.find(ids[i])) {
+
+				meshes.push_back(p_library->get_item_mesh(ids[i]));
+				transforms.push_back(mesh_instances[ids[i]]->get_transform());
+			}
 		}
 
-		Vector<Ref<Texture> > textures = EditorInterface::get_singleton()->make_mesh_previews(meshes, EditorSettings::get_singleton()->get("editors/grid_map/preview_size"));
+		Vector<Ref<Texture> > textures = EditorInterface::get_singleton()->make_mesh_previews(meshes, &transforms, EditorSettings::get_singleton()->get("editors/grid_map/preview_size"));
+		int j = 0;
 		for (int i = 0; i < ids.size(); i++) {
-			p_library->set_item_preview(ids[i], textures[i]);
+
+			if (mesh_instances.find(ids[i])) {
+
+				p_library->set_item_preview(ids[i], textures[j]);
+				j++;
+			}
 		}
 	}
 }