1. A method, including steps of at a controlling device, assigning a set of objects to be rendered; distributing those objects to a set of rendering devices; at each rendering device, (1) computing an image in response to an assigned object, the image including a set of pixels, each pixel having an α-value, (2) computing multiple overlapping images, (3) using a graphics processor to blend those images; wherein each rendering device spoofs the α-value of each pixel with a pixel feature other than opacity, whereby the graphics processor delivers useful α-values while still delivering correct color values, for each pixel; whereby the images produced by each rendering device include transparency information sufficient to combine those images using transparency blending.