public void removeHorizontalTranslation( Vector2 deltaMovement )
{
// http://dev.yuanworks.com/2013/03/19/little-ninja-physics-and-collision-detection/
// fix is the vector that is only in the y-direction that we want. Projecting it on the normal gives us the
// responseDistance that we already have (MTV). We know fix.x should be 0 so it simplifies to fix = r / normal.y
// fix dot normal = responseDistance
// check if the lateral motion is undesirable and if so remove it and fix the response
if( Math.Sign( normal.X ) != Math.Sign( deltaMovement.X ) || ( deltaMovement.X == 0f && normal.X != 0f ) )
{
var responseDistance = minimumTranslationVector.Length();
var fix = responseDistance / normal.Y;
// check some edge cases. make sure we dont have normal.x == 1 and a super small y which will result in a huge
// fix value since we divide by normal
if( Math.Abs( normal.X ) != 1f && Math.Abs( fix ) < Math.Abs( deltaMovement.Y * 3f ) )
{
minimumTranslationVector = new Vector2( 0f, -fix );
}
}
}
