I’ll try to be as clear as I can to be easily understood.
I know that by means of certain variables passed from vs to fs values are interpolated so each fragment gets the appropriate ones (like the fragment coords).
I want to take advantage of this “free” interpolation and input a second set of 4 vertices in vs for a second texture so that in fs I can mix texture with a displaced (projected) texture just by specifying texCoord and (ready interpolated)texCoord.
- Is it possible in the first place?
- Does GL know to match current fragment coords to the respective coords of the second set of vertices?
- In what order are the vertices to be specified to match?
- What qualifiers can the vertices be? (attributes, varyings) Can you give an example?
What steps do I have to do? Where can I read about them?