Projection Mapping and Masking

Hey Guys,

we, some students, are realizing a game based on projection mapping with 3 projectors. There is a round table in the middle of the room with 10-15 white cubes (15cm x 15cm) on top. Our problem is that we need a way to create masks (dynamically?) which give us the possibility to select which side of each cube is projected on.
Example: Projector one beams on side A and B and projector 2 on the 2 opposite sides and projector 3 on the cubes top side.
We already managed to give each side of a cube a different texture.
Does anyone have an idea how to do that? Thanks!!!


What do you mean that you managed to give each side a texture ? by projecting on it ?

are the cubes gonna be static ? or dynamic ? in other words you want them to change places ? you want to track and map textures at the same time ? or just map fix cubes ?


luckily the cubes are static, so they do not move :)

By giving each side a texture, i meant we used an .x File with 6 subsets so that we have a different texture for each side. One idea was to have some white (the projected sides) and some black sides to create an alpha mask directly from the renderer. But unfortunately i have no idea how to use the render output as a mask for the projectors renderer.
I made a quick example patch. Actually i don’t know if this render-mask idea is a good way…


Example Patch (6.5 kB)


If the cubes and projectors never move you could use a spread of quads with unique homography for each one. See the Homography node helppatch for an easy way to set keystoned rectangles just by right clicking and dragging rather than working it out in 3D. Then a spread of textures for each quad allows you to control what is projected on them.