Homography texture transform

vvvv beta question
1

ahoj! It is possible to operate a “texture transform” in order to show on a quad a non-square section of a texture? This is what I mean:

I want to see on the quad the section of the texture highlighted in white… this is my goal:

I tryed to apply the homography tranform and the inverse of it, but no luck till now

any idea?

texturemap.rar (56.5 kB)

2

Yeah, use a Constant fx and change the tex coords.

3

i think you have to pass the homography matrix as an extra pin into a pixel shader and apply it to the texture coordinates which should be (u, v, 0, 1) and then divide by w to get the correct u and v after the transformation. its important to do it in the pixel shader because otherwise you will just get a linear interpolation which will not match the perspective transformation.