isLineVisible method
Checks if line is visible in the current viewport.
Implementation
@override
bool isLineVisible(Vector3 a, Vector3 b) {
if (a.x < -_viewPortWidth && b.x < -_viewPortWidth) return false;
if (a.x > _viewPortWidth && b.x > _viewPortWidth) return false;
if (a.y < -_viewPortHeight && b.y < -_viewPortHeight) return false;
if (a.y > _viewPortHeight && b.y > _viewPortHeight) return false;
if (a.z > _maxDepth || b.z > _maxDepth) return false;
return true;
}