Can someone please explain the representation of reflection and scaling with the matrix? What would the result matrices look like if, for instance, you were scaling by 3?

@unreal I think its helpful to write out examples - in the 2D case its doable with pencil and paper. Think about doing the matrix multiplication between our scaling matrix and the vector [X, Y] - we get [.5X, 2Y]. If we wanted to scale X by 3, our top entry of our scaling matrix would multiply X by 3 and Y by 0 - aka [3 0]. Next we scale Y by 3 and X by zero in the bottom - [0 3]. Thus our scaling matrix is [3 0, 0 3]. For reflection, imagine you had a 2x2 matrix and wanted all the X coordinates to be flipped (multiplied by -1), then we can use a scaling matrix with the same logic, but instead of 3 we put -1 for the top row (and we wouldn't scale or reflect in the y direction so we would use [0 1] for the bottom.)

@unreal Here's a link with some additional diagrams that might help: https://www.tutorialspoint.com/computer_graphics/2d_transformation.htm