Calculate two points of triangle with given Z

Question

I want to calculate the two points of a 3D triangle that have a specified Z coordinate. I guess the way to do this would be to somehow create a plane which is perfectly flat with my given Z coordinate and then calculate where the triangle intersects with it (or is this wrong).

If you know how to do this in any way please help. I have searched for but have not really found anything that seems to work.

Answer 1

Assuming your triangle is defined by three points where T0 is base left, T1 is base right and T2 is tip. And a lot of other assumptions about how the triangle is aligned etc:

public bool GetIntersect(Vector3 T0, Vector3 T1, Vector3 T2, float Z, out Vector3 P0, out Vector3 P1)
{
    if (!((Z <= T2.Z) && (Z >= T0.Z) && (Z >= T1.Z)))
        return false;

    var left = T2 - T0;
    left *= 1f / left.Z;

    var right = T2 - T1;
    right * 1f / right.Z;

    P0 = T0 + (left * (Z - T0.Z));
    P1 = T1 + (right * (Z - T1.Z));

    return true;
}

PS; Uppercase in parameter names are bad! don't do that! I just don't care to fix my mistake right now :P