hide a polygon

is there a possibility to draw a polygon so that it affects the depth and stencil buffers, but not the color buffer? (i.e. the polygon is completely invisible, but exists)
i think drawing it with a zero alpha value won´t do the trick…
i know you can switch the depth buffer to read only with glDepthMask(), is there anything similar for the frame buffer?

regards

eik

glColorMask(0,0,0,0) to set no color buffer drawing. glColorMask(1,1,1,1) to turn it back on.

j