Default to trimesh for generated collision shapes in Advanced Import Settings

This avoids using convex decomposition every time collision is enabled
on a mesh, which can be extremely slow on complex meshes (such as entire
levels).

editor/import/3d/resource_importer_scene.cpp

@@ -1658,7 +1658,7 @@ void ResourceImporterScene::get_internal_import_options(InternalImportCategory p
 			r_options->push_back(ImportOption(PropertyInfo(Variant::BOOL, "generate/physics", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_UPDATE_ALL_IF_MODIFIED), false));
 			r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "generate/navmesh", PROPERTY_HINT_ENUM, "Disabled,Mesh + NavMesh,NavMesh Only"), 0));
 			r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "physics/body_type", PROPERTY_HINT_ENUM, "Static,Dynamic,Area"), 0));
-			r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "physics/shape_type", PROPERTY_HINT_ENUM, "Decompose Convex,Simple Convex,Trimesh,Box,Sphere,Cylinder,Capsule", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_UPDATE_ALL_IF_MODIFIED), 0));
+			r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "physics/shape_type", PROPERTY_HINT_ENUM, "Decompose Convex,Simple Convex,Trimesh,Box,Sphere,Cylinder,Capsule", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_UPDATE_ALL_IF_MODIFIED), 2));
 			r_options->push_back(ImportOption(PropertyInfo(Variant::OBJECT, "physics/physics_material_override", PROPERTY_HINT_RESOURCE_TYPE, "PhysicsMaterial"), Variant()));
 			r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "physics/layer", PROPERTY_HINT_LAYERS_3D_PHYSICS), 1));
 			r_options->push_back(ImportOption(PropertyInfo(Variant::INT, "physics/mask", PROPERTY_HINT_LAYERS_3D_PHYSICS), 1));

editor/import/3d/resource_importer_scene.h

@@ -322,7 +322,7 @@ public:
 template <class M>
 Vector<Ref<Shape3D>> ResourceImporterScene::get_collision_shapes(const Ref<ImporterMesh> &p_mesh, const M &p_options, float p_applied_root_scale) {
 	ERR_FAIL_COND_V(p_mesh.is_null(), Vector<Ref<Shape3D>>());
-	ShapeType generate_shape_type = SHAPE_TYPE_DECOMPOSE_CONVEX;
+	ShapeType generate_shape_type = SHAPE_TYPE_TRIMESH;
 	if (p_options.has(SNAME("physics/shape_type"))) {
 		generate_shape_type = (ShapeType)p_options[SNAME("physics/shape_type")].operator int();
 	}
@@ -480,7 +480,7 @@ template <class M>
 Transform3D ResourceImporterScene::get_collision_shapes_transform(const M &p_options) {
 	Transform3D transform;
 
-	ShapeType generate_shape_type = SHAPE_TYPE_DECOMPOSE_CONVEX;
+	ShapeType generate_shape_type = SHAPE_TYPE_TRIMESH;
 	if (p_options.has(SNAME("physics/shape_type"))) {
 		generate_shape_type = (ShapeType)p_options[SNAME("physics/shape_type")].operator int();
 	}