modify method

BufferGeometry modify(BufferGeometry geometry, int count)

Implementation

BufferGeometry modify(BufferGeometry geometry, int count ) {
	geometry = geometry.clone();
	final attributes = geometry.attributes;

    List<String> keys = [];// this modifier can only process indexed and non-indexed geomtries with a position attribute
	attributes.keys.forEach((name){
      keys.add(name);
	});

    for(String name in keys){
		if(name != 'position' ){
        geometry.deleteAttribute( name );
      }
    }

	geometry = BufferGeometryUtils.mergeVertices( geometry );

	//
	// put data of original geometry in different data structures
	//

	final List<Vertex> vertices = [];
	final List<Tri> faces = [];

	// add vertices

	final positionAttribute = geometry.getAttribute( 'position' );

	for ( int i = 0; i < positionAttribute.count; i ++ ) {
		final v = Vector3().fromBufferAttribute( positionAttribute, i );
		final vertex = Vertex( v );
		vertices.add(vertex);
	}

	// add faces

	BufferAttribute<NativeArray<num>>? index = geometry.getIndex();

	if ( index != null ) {
		for ( int i = 0; i < index.count; i += 3 ) {
			final a = index.getX( i )!.toInt();
			final b = index.getX( i + 1 )!.toInt();
			final c = index.getX( i + 2 )!.toInt();

			final triangle = Tri( vertices[ a ], vertices[ b ], vertices[ c ], a, b, c );
			faces.add( triangle );
		}
	}
    else{
		for(int i = 0; i < positionAttribute.count; i += 3){

			final a = i;
			final b = i + 1;
			final c = i + 2;

			final triangle = Tri(vertices[a], vertices[b], vertices[c], a, b, c);
			faces.add(triangle);
		}
	}

	// compute all edge collapse costs

	for ( int i = 0, il = vertices.length; i < il; i ++ ) {
		SMUtil.computeEdgeCostAtVertex( vertices[ i ] );
	}

	Vertex? nextVertex;
	int z = count;

	while (z != 0) {
		nextVertex = SMUtil.minimumCostEdge(vertices);

		if (nextVertex == null) {
			print( 'THREE.SimplifyModifier: No next vertex' );
			break;
		}

		SMUtil.collapse( vertices, faces, nextVertex, nextVertex.collapseNeighbor);
      z--;
	}

	//

	final simplifiedGeometry = BufferGeometry();
	List<double> position = [];
	//
	for (int i = 0; i < vertices.length; i ++ ) {
		final vertex = vertices[i].position;
      position.addAll([vertex.x,vertex.y,vertex.z]);
		// cache final index to GREATLY speed up faces reconstruction
		vertices[i].id = i;
	}

	//
    List<int> indexs = [];
	for (int i = 0; i < faces.length; i ++ ) {
		final face = faces[i];
      indexs.addAll([face.v1!.id,face.v2!.id,face.v3!.id]);
	}

	//
	simplifiedGeometry.setAttribute( 'position', Float32BufferAttribute( Float32Array.from(position), 3 ) );
	simplifiedGeometry.setIndex( indexs );

	return simplifiedGeometry;
}