Figure out texture coordinate from 4 others?

Question

Lets say I have 4 verticies and their texture coordinates. How could I then figure out the texture coords of a 5th vertex?

Thanks

say I have:

v1 = (0,0) tex coord(1,0)
v2....
v3...
v4...
v5 = (15,15) tex coord = ??

yea linear interpolation I suppose,

To figure out the coords I do:

vec.x / polywidth;
vec.y / polyheight;

Answer 1

texture mapping is about mapping a 2d space to your 3d model. There is no generic way to extrapolate texture coordinates, because those completely depend on how you want to map your texture to your surface. More to the point, there are many possible texture coordinates, that will map a different part of your texture to your mesh.

Now... If your mesh is a regular 2D grid (a special case), on which you want to map a texture uniformly (another special case), then yeah, linear interpolation of the texture coordinates based on the vertex positions would work.