Pumpkin Chop released on Xbox Live Indie Games

Pumpkin Chop is a 3D Pumpkin Carving simulator that allows complete freedom when carving by using freehand tools rather than limiting you to preset cookie cutter shapes. After you've carved your masterpiece, theres two 3D Showoff scenes with automatic camera movement so you can display them to all the world (or whatever part of the world you can fit around your tv anyway)




The carving is accomplished by generating an alpha mask for the cutout areas, and applying that to the pumpkin. Rather than be just the outer surface, the pumpkin has a bunch of shells and slices inside it, with a shader that generates color based on position rather than normal. When you remove the alpha parts from it, exposing these inner shells, they give the illusion that they're solid.

I didn't want to have to deal with projecting rays and calculating which triangle it hits and what exact point it intersects on it, so I went with a far simpler, and somewhat more unique, method of determining the 3d coordinate of the cut cursor. In the carve mode, whenever the camera is moved, I render both the pumpkin's depth and its uv coordinates to render targets. Then when the user adds a point to the carving, I can use the information from these two buffers to determine its world position (by unprojecting from screenpos with that depth value) and what the exact uv coordinate is.

Triangulation is far simpler in 2D, so when generating my poly to triangulate, rather than use the world positions, I use those uv positions, which automatically gives me a perfect flat representation of the shape. Then I just triangulate that and fill the triangles black on a white background to get my alpha map.



Pumpkin Chop is just 80 Points on Xbox Live Indie Games (about $1) so you really have no excuse not to buy something this cool. Or you could at least try the demo. It allows everything except saving (unless you buy it) and has an 8 minute time limit. Don't have an Xbox? They've dropped in price lately, go buy one so you can pick up Pumpkin Chop ;)