Stretching a texture over multiple faces

Question

I have a grid of vertices that I'm using as the ground for my game in XNA. I have a effect file / shader which handles texturing and lighting. Right now I have it so the texture tiles across each face of the grid, but the texture i'm using is 4096x4096 and i'd like to have it completely stretched across all the faces of this grid instead of repeating itself over each face. How would I go about doing this?

Thanks

Answer 1

Assuming the following:

• (0,0) is the top-left coordinate.
• Each vertex in the grid is equidistant in x and y.

---

float u, v;
for( int Row(0); Row <= NumberOfRows; ++Row )
{
    for( int Col(0); Col <= NumberOfCols; ++Col)
    {
        u = Row / float(NumberOfRows);
        v = Col / float(NumberOfCols);

        // Store u and v
     }
}

This code creates UV coordinates with a constant increment from 0 to 1 in both x and y. This will allow you to map one square texture over the full grid. All you need to remember is that texture coordinates rely on the smallest extremity being equal to 0 and the largest extremity being equal to 1 of the object your mapping.