public void CrossProduct()
{
var v1 = PointType.Vector(1, 2, 3);
var v2 = PointType.Vector(2, 3, 4);
var expected1 = PointType.Vector(-1, 2, -1);
var expected2 = PointType.Vector(1, -2, 1);
Assert.Equal(expected1, PointType.CrossProduct(v1, v2));
Assert.Equal(expected2, PointType.CrossProduct(v2, v1));
}
public static Matrix ViewTransform(PointType from, PointType to, PointType up)
{
var forward = (to - from).Normalize();
var left = PointType.CrossProduct(forward, up.Normalize());
var trueUp = PointType.CrossProduct(left, forward);
var orientation = new Matrix(4, 4);
orientation.SetRow(0, new double[] { left.X, left.Y, left.Z, 0 });
orientation.SetRow(1, new double[] { trueUp.X, trueUp.Y, trueUp.Z, 0 });
orientation.SetRow(2, new double[] { -forward.X, -forward.Y, -forward.Z, 0 });
orientation.SetRow(3, new double[] { 0, 0, 0, 1 });
var t = Translation(-from.X, -from.Y, -from.Z);
return(orientation * t);
}