x194@cs.utexas.edu (Classroom Account) (09/01/90)
I'm currently trying to render an axis at an arbitrary angle using Adobe Illustrator with program generated instructions. The problem is that when I render a 45 degree axis, each individual tick will vary from a true 45 degree angle by up to 5 degrees, causing significant aliasing. If I render the axis vertically and use AI to rotate the figure precisely 45 degrees, the same effect occurs. But if I modify the PostScript code to include <45 rotate> after the state initialization it comes out looking fine. Now, if I go into AI and zoom into the line, it continues to be aliased at the very highest magnification, even though it should be a relatively straight 45 degree line. If I grab the end point off the axis and twiddle with it, I can get it into line, but a given line can be off the diagonal in either direction. I'm using a single double precision matrix transformation to translate, scale and rotate the axis. I tried snapping the points to the output device's raster grid, with no significant difference in quality. Any advice on how PostScript is doing it (transforming the entire line point by point?) or how I might be able to get better results would be most welcome.