ellipse-test
Tests two applications of Gresenham's algorithm for drawing ellipses.
ellipse.cppcontains the two algorithmsmain.cppcontains the test procedure - making sure the new one doesn't try to write a pixel twice, and reports when the algorithms draw in different places.alg-other.hcontains other functions required by the ellipse algorithms.
Sample output in output-50-by-50. Each block starts with the width/height of the ellipse, the difference count in output, and a visual. X indicates where both algorithms drew. . where neither. o where only the old one, and n where only the new one.
I think primarily the new one draws more inward outlines, especially at a sharp turn. It has no holes where the old one does though. See outputs for coordinates (28 8) (28 9), and (44 10) to (47 11).