| static private Dot2D ( Microsoft.Xna.Framework.Vector3 &left, Microsoft.Xna.Framework.Vector3 &right ) : float | ||
| left | Microsoft.Xna.Framework.Vector3 | A vector. |
| right | Microsoft.Xna.Framework.Vector3 | Another vector |
| return | float | |
/// <summary>
/// Finds the distance between a point and triangle ABC.
/// </summary>
/// <param name="p">A point.</param>
/// <param name="a">The first vertex of the triangle.</param>
/// <param name="b">The second vertex of the triangle.</param>
/// <param name="c">The third vertex of the triangle.</param>
/// <param name="height">The height between the point and the triangle.</param>
/// <returns>A value indicating whether the point is contained within the triangle.</returns>
internal static bool PointToTriangle(Vector3 p, Vector3 a, Vector3 b, Vector3 c, out float height)
{
Vector3 v0 = c - a;
Vector3 v1 = b - a;
Vector3 v2 = p - a;
float dot00, dot01, dot02, dot11, dot12;
Vector3Extensions.Dot2D(ref v0, ref v0, out dot00);
Vector3Extensions.Dot2D(ref v0, ref v1, out dot01);
Vector3Extensions.Dot2D(ref v0, ref v2, out dot02);
Vector3Extensions.Dot2D(ref v1, ref v1, out dot11);
Vector3Extensions.Dot2D(ref v1, ref v2, out dot12);
//compute barycentric coordinates
float invDenom = 1.0f / (dot00 * dot11 - dot01 * dot01);
float u = (dot11 * dot02 - dot01 * dot12) * invDenom;
float v = (dot00 * dot12 - dot01 * dot02) * invDenom;
const float EPS = 1E-4f;
//if point lies inside triangle, return interpolated y-coordinate
if (u >= -EPS && v >= -EPS && (u + v) <= 1 + EPS)
{
height = a.Y + v0.Y * u + v1.Y * v;
return(true);
}
height = float.MaxValue;
return(false);
}
internal static void ProjectPoly(Vector3 axis, Vector3[] poly, int npoly, out float rmin, out float rmax)
{
Vector3Extensions.Dot2D(ref axis, ref poly[0], out rmin);
Vector3Extensions.Dot2D(ref axis, ref poly[0], out rmax);
for (int i = 1; i < npoly; i++)
{
float d;
Vector3Extensions.Dot2D(ref axis, ref poly[i], out d);
rmin = Math.Min(rmin, d);
rmax = Math.Max(rmax, d);
}
}
