Hi

I am wanting to do collision detection.

In order to do this I need to keep track of the vertices of my polygons.

So I am storing all the vertices and then I am multiplying them by the modelview matrix, then the product of that I multiply

by the projection matrix (which is a perspective one).

To test whether my values are correct I then load the identity matrix and draw a white line using the same x and z coords

that I calculated, (that is where my vertex should lie) the white line is drawn down the y axis so I don't bother calculating a y value.

This doesn't work for any transformations.

Either I am doing the matrix multiplications wrong or I am using the wrong matices.

If there is a simpler way of keeping track of where my vertices are please let me know.

If I can read the vertex values straight from the computer without doing any calcs please let me know.