三角形と点の当たり判定

float sign (fPoint p1, fPoint p2, fPoint p3)

{

return (p1.x - p3.x) * (p2.y - p3.y) - (p2.x - p3.x) * (p1.y - p3.y);

}

bool PointInTriangle (fPoint pt, fPoint v1, fPoint v2, fPoint v3)

{

bool b1, b2, b3;

b1 = sign(pt, v1, v2) < 0.0f;

b2 = sign(pt, v2, v3) < 0.0f;

b3 = sign(pt, v3, v1) < 0.0f;

return ((b1 == b2) && (b2 == b3));

}