WaterRippleBrush(id[, wavelength, amplitude, phase, cx, cy])
phasecontrol the look of the ripples, whereas the
cyarguments can be used to specify the center point of the ripple. This point must be specified as a floating point value ranging from 0.0 (left/top) to 1.0 (right/bottom). The center of the brush is thus at position 0.5/0.5.