Sit, Ubu, sit! Good dog.
Many game engines are using deferred rendering these days as opposed to forward rendering. In addition, many movie shots have been authored with deferred techniques and then assembled and shaded in Nuke. The concept for both real-time engines and offline renderers is basically the same; to encode 3d data into 2d space (buffers) and then solve for the lighting/shading as a post process. If you are interested in lighting/shading in post, check out the Postlight tool by Andy Nicholas.
This deferred texture mapping test is a similar idea and mimics thistool by RevisionFX. For offline rendering, this additional UV vector pass can save re-rendering an image/animation by allowing me to swap textures after rendering is complete.
The Component Parser is the compositing node used to map the texture to the UV vector data. The variable a1 = horizontal pixel count of the image and variable a2 = the vertical pixel count.
Objects can be easily textured in post. Swapping textures is real-time without the need to re-render.
This is a great cheat for low cost 'dynamic' lights. If you bake lightmaps in passes, this is a very easy effect to author.
Essentially I combine two lightmaps; adding the dynamic map over the base map. For this demo, I do exactly that. In practical application, you would not want to double your lightmap textures space for a whole level. Instead, create a pass where duplicate chunks of localized geometry will hold low resolution dynamic maps (or even make a larger texture sheet for all the dynamic maps in your level, a 512x512 will do) and bake to a new set of UVs.
Derek Jenson Blog
My website serves to archive experiments, document projects, share techniques, and motivate further exploration & artistry in 3d space.