@Override
	protected Paint getVertexShapePaint() {
		FcgLevel level = vertex.getLevel();
		FcgDirection direction = level.getDirection();
		if (direction.isSource()) {
			return getDefaultVertexShapeColor();
		}
		else if (direction.isIn()) {
			return inPaint;
		}
		else {
			return outPaint;
		}
	}
A vertex shape provider for the {@link FunctionCallGraphPlugin}.
Ghidra/Features/GraphFunctionCalls/src/main/java/functioncalls/graph/FcgVertexShapeProvider.java