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

问题

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?

回答1:

I would avoid rise/run calcs as they could produce a NaN if terrain is vertical.

//currentPosition & targetPosition should be known to you

Vector3 potentialMove = Vector3.Normalize(targetPosition - currentPosition);

float steepness = Vector3.Dot(Vector3.Up, potentialMove);
if( steepness < 0.85f && steepness > -0.85f) // set to taste. 1 is vertically up, 0 is flat, -1 is vert down
{
  //allow move
  currentPosition = targetPosition
}

回答2:

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 }
}

来源：https://stackoverflow.com/questions/9944541/xna-prevent-to-go-down-slopes-or-up-hills-that-are-too-steep