Drag the control points around to deform the image.
This quad renderer is somewhat well optimized, and in fact probably only works on this image, as the pen size is constant. On my computer it is now fast enough to render updates to the quadrilateral in realtime. UPDATE 9/2/2017: I've change the project so it only refreshes when necessary, which makes it slightly more responsive on my computer. Thanks to the remix by @CoolerGamingStudio to remind me to fix this
