xna prevent to go down slopes or up hills that are too steep

Question

how can i prevent to go down slopes or up hills that are too steep on heightmap terrain? I have a 3d camera that moves on a terrain, it now moves on any place even on big slopes and on hills that are too steep, what can I do?

Answer 1

You should predict where you're going to end up if you attempt to move in a direction, and then figure out if the slope between your current point and your future point is too steep:

if(forward key pressed) {
    get location I'll end up at
    get the Z of that location
    calculate slope using rise/run formula
    if(slope is too steep) {
        don't move
    }
    else { move to the future location }
}