notes.txt

/* Calculate FOV
      Basic trigonometry:
      ~ FOV = atan(halfScreenWidth / distanceFromScreen)
      Epiphany: No fov because looking at different angles
                generates inconsistant fovs
    */
    // this.fovx = atan(SCREEN_WIDTH / 2 / this.near);
    // this.fovy = atan(SCREEN_HEIGHT / 2 / this.near);

/**
* findLinePlaneIntersectionCoords (to avoid requiring unnecessary instantiation)
* Given points p with px py pz and q that define a line, and the plane
* of formula ax+by+cz+d = 0, returns the intersection point or null if none.
* <a, b, c> is the normal vector of the plane
*/
function findLinePlaneIntersectionCoords(px, py, pz, qx, qy, qz, p1, p2, p3) {
  let N = getPlaneNormalVector(p1, p2, p3);
  let a = N.x, b = N.y, c = N.z, d = 100;
  
  let tDenom = a*(qx-px) + b*(qy-py) + c*(qz-pz);
  if (tDenom == 0) return null;

  let t = - ( a*px + b*py + c*pz + d ) / tDenom;

  return {
      x: (px+t*(qx-px)),
      y: (py+t*(qy-py)),
      z: (pz+t*(qz-pz))
  };
}