Retrieve texture coordinates on a 3D Model?

Question

Is it possible to retrieve the texture coordinates of an object, for example through hittesting?

As an example: I use a 1920x1080 texture on a simple plane, and I want to get the coordinates 1920, 1080 if I click in the right bottom. (The model is in reality slightly more complex, so trying to calculate the position via math isn't as easy)

Answer 1

When math does not work for some reasons, I used to do the following graphic hit-test: assign unique colors to each texel of your plane, then do one frame rendering to an offscreen surface with lighthing and effects disabled, then read pixel color under the cursor and translate its value back to coordinates. This is quite efficient on complex models when you don't need to do such lookups too often (say, games), because reading pixels back will stop graphics hardware pipeline and drain the performance. Also, this potentially would work with any projections: ortho or perspective.