representing a shear/skew with only rotation and scaling

clickbait title: “rederiving an extremely elegant equation from a classic 1990 computer graphics book” note: this post uses MathML for formatting the math. this is supported by all the major browsers (I tested chromium, firefox, and pale moon), but more obscure browsers might not render it I’m in resonite —as I am—hanging out with some critters in a world—as one does. sparsely out of the corner of…