public static bool IsPointInTriangle(Math.Vector2 point, Math.Vector2 a, Math.Vector2 b, Math.Vector2 c, out Math.Vector2 uv)
{
Math.Vector2 v0 = c - a;
Math.Vector2 v1 = b - a;
Math.Vector2 v2 = point - a;
float dot00 = v0.Dot(v0);
float dot01 = v0.Dot(v1);
float dot02 = v0.Dot(v2);
float dot11 = v1.Dot(v1);
float dot12 = v1.Dot(v2);
float invDenom = 1.0f / (dot00 * dot11 - dot01 * dot01);
uv.X = (dot11 * dot02 - dot01 * dot12) * invDenom;
uv.Y = (dot00 * dot12 - dot01 * dot02) * invDenom;
return(uv.X >= 0 && uv.Y >= 0 && uv.X + uv.Y < 1.0f);
}
public static bool TestTriangleBox(Math.Vector2 a, Math.Vector2 b, Math.Vector2 c, Math.Vector2 boxMin, Math.Vector2 boxMax)
{
Math.Vector2 ab = (b - a).Normalize();
Math.Vector2 ac = (a - c).Normalize();
Math.Vector2 bc = (c - b).Normalize();
// calc the normals
/*Utils.Swap(ref ab.X, ref ab.Y);
* Utils.Swap(ref ac.X, ref ac.Y);
* Utils.Swap(ref bc.X, ref bc.Y);
* ab.X = -ab.X;
* ac.X = -ac.X;
* bc.X = -bc.X;*/
// project the triangle onto the 1st axis of the triangle
float dotA = a.Dot(ab);
float dotB = b.Dot(ab);
float dotC = c.Dot(ab);
float dotMax = System.Math.Max(dotA, System.Math.Max(dotB, dotC));
float dotMin = System.Math.Min(dotA, System.Math.Min(dotB, dotC));
// project the box onto 1st axis of triangle
float boxA = boxMin.X * ab.X + boxMin.Y * ab.Y;
float boxB = boxMax.X * ab.X + boxMin.Y * ab.Y;
float boxC = boxMax.X * ab.X + boxMax.Y * ab.Y;
float boxD = boxMin.X * ab.X + boxMax.Y * ab.Y;
float boxDotMax = System.Math.Max(boxA, System.Math.Max(boxB, System.Math.Max(boxC, boxD)));
float boxDotMin = System.Math.Min(boxA, System.Math.Min(boxB, System.Math.Min(boxC, boxD)));
if (boxDotMax < dotMin || dotMax < boxDotMin)
{
return(false);
}
// project the triangle onto 2nd axis of triangle
dotA = a.Dot(ac);
dotB = b.Dot(ac);
dotC = c.Dot(ac);
dotMax = System.Math.Max(dotA, System.Math.Max(dotB, dotC));
dotMin = System.Math.Min(dotA, System.Math.Min(dotB, dotC));
// project the box onto 1st axis of triangle
boxA = boxMin.X * ac.X + boxMin.Y * ac.Y;
boxB = boxMax.X * ac.X + boxMin.Y * ac.Y;
boxC = boxMax.X * ac.X + boxMax.Y * ac.Y;
boxD = boxMin.X * ac.X + boxMax.Y * ac.Y;
boxDotMax = System.Math.Max(boxA, System.Math.Max(boxB, System.Math.Max(boxC, boxD)));
boxDotMin = System.Math.Min(boxA, System.Math.Min(boxB, System.Math.Min(boxC, boxD)));
if (boxDotMax < dotMin || dotMax < boxDotMin)
{
return(false);
}
// project the triangle onto 3rd axis of triangle
dotA = a.Dot(bc);
dotB = b.Dot(bc);
dotC = c.Dot(bc);
dotMax = System.Math.Max(dotA, System.Math.Max(dotB, dotC));
dotMin = System.Math.Min(dotA, System.Math.Min(dotB, dotC));
// project the box onto 1st axis of triangle
boxA = boxMin.X * bc.X + boxMin.Y * bc.Y;
boxB = boxMax.X * bc.X + boxMin.Y * bc.Y;
boxC = boxMax.X * bc.X + boxMax.Y * bc.Y;
boxD = boxMin.X * bc.X + boxMax.Y * bc.Y;
boxDotMax = System.Math.Max(boxA, System.Math.Max(boxB, System.Math.Max(boxC, boxD)));
boxDotMin = System.Math.Min(boxA, System.Math.Min(boxB, System.Math.Min(boxC, boxD)));
if (boxDotMax < dotMin || dotMax < boxDotMin)
{
return(false);
}
return(true);
}
