whirlpool

This procedure takes two arguments: a Rivl image (image) and a double value between 0 and 1 (p). The call to im_scaleC! reduces image by a factor of 1-p, and destructively modifies it. The call to im_rotateC! rotates image about its center by an angle proportional to p, and by destrucively modifying it, stores the result in image, which is returned.

proc whirlpool {image p} {
	im_scaleC! image [expr 1- $p]
	im_rotateC! image [expr 360 * $p]
	return $image
	}

Output from whirlpool for p = 0.0, 0.1, 0.4, 0.7