/// <summary>
/// Build a look at view matrix.
/// </summary>
/// <param name="eye">The eye.</param>
/// <param name="center">The center.</param>
/// <param name="up">Up.</param>
/// <returns></returns>
public static mat4 lookAt(vec3 eye, vec3 center, vec3 up)
{
vec3 forward = (center - eye).normalize();
vec3 right = forward.cross(up).normalize();
vec3 standardUp = right.cross(forward);
mat4 Result = new mat4(1);
// Left (X) Axis
Result[0, 0] = right.x;
Result[0, 1] = standardUp.x;
Result[0, 2] = -forward.x;
// Up (Y) Axis
Result[1, 0] = right.y;
Result[1, 1] = standardUp.y;
Result[1, 2] = -forward.y;
// Forward (Z) Axis
Result[2, 0] = right.z;
Result[2, 1] = standardUp.z;
Result[2, 2] = -forward.z;
// Translation
Result[3, 0] = -right.dot(eye); // dot(s, eye);
Result[3, 1] = -standardUp.dot(eye); // dot(u, eye);
Result[3, 2] = forward.dot(eye); // dot(f, eye);
return(Result);
}
/// <summary>
/// Build a look at view matrix.
/// </summary>
/// <param name="eye">The eye.</param>
/// <param name="center">The center.</param>
/// <param name="up">Up.</param>
/// <returns></returns>
public static mat4 lookAt(vec3 eye, vec3 center, vec3 up)
{
vec3 f = (center - eye); f.Normalize();
vec3 s = f.cross(up); s.Normalize();
vec3 u = s.cross(f);
mat4 Result = new mat4(1);
Result[0, 0] = s.x;
Result[1, 0] = s.y;
Result[2, 0] = s.z;
Result[0, 1] = u.x;
Result[1, 1] = u.y;
Result[2, 1] = u.z;
Result[0, 2] = -f.x;
Result[1, 2] = -f.y;
Result[2, 2] = -f.z;
Result[3, 0] = -s.dot(eye); // dot(s, eye);
Result[3, 1] = -u.dot(eye); // dot(u, eye);
Result[3, 2] = f.dot(eye); // dot(f, eye);
return(Result);
}