digraph G {
    graph[rankdir=LR,fontname="Source Sans Pro"];
    node[shape=box,fontname="Source Sans Pro"];
    edge[arrowhead=vee];
    subgraph cluster_CPU {
        Simplify -> Tile -> Cull -> Pack;
        label="CPU";
    }
    subgraph clusterGPU {
        Fill -> Shade;
        label="GPU";
    }
    Pack -> Fill;
    Paths[shape=none];
    Image[shape=none];
    Paths -> Simplify;
    Shade -> Image;
}