Re: More OpenGL-related questions

[Dan K. <da...@ch...>]

  Well, you'd still need the vertex parameter, but etypecase would
let you do away with the format parameter.  Unfortunately, you can't
check the types of the coordinates at macro-expansion time because
they may not be known.  If you wanted to incur a runtime penalty,
you could do something like:

(defun gl-vertex (x &optional (y 0) (z 0) (w 1) &key (vertex nil))
  (flet ((float-type (n) (etypecase n
				    (integer 0)
				    (short-float 1)
				    (single-float 2)
				    (double-float 3))))
	(let ((type (apply #'max (mapcar #'float-type (list x y z w)))))
	     (apply (nth (+ type (if vertex 4 0))
			 '(#'glVertex4i #'glVertex4f #'glVertex4s
			   #'glVertex4d #'glVertex4iv #'glVertex4fv
			   #'glVertex4sv #'glVertex4dv))
		    (mapcar (lambda (n)
				    (case type
					  (0 (floor n))
					  (1 (float n 1s0))
					  (2 (float n 1f0))
					  (3 (float n 1d0))))
			    (list x y z w))))))

  I doubt I've got the mapping of Lisp types to C types exactly
right, you'd have to go through and correct that.

| Dan Knapp, Knight of the Random Seed
| http://brain.mics.net/~dankna/
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