iphone - Is there a way to stop an object from passing through another object, but only if it approaches from one side? -


i making pong style game , trying ball bounce off of 1 side of paddle , bounce different direction off of side of paddle. have:

if (cgrectintersectsrect(cgrectinset(_ball.frame, -1, -1), _paddle1.frame) ||      cgrectintersectsrect(cgrectinset(_ball.frame, -1, -1), _paddle2.frame)) {             ballvelocity.y *= -1;         }

where paddle1 bottom paddle , paddle2 top paddle. right now, ball bounce off top , bottom of paddle stuck inside paddle if enters either paddle side or @ major angle. want bounce off side , change direction on x-axis.

rather trying fix "stuck ball" problem changing velocity, move ball outside of paddle when has intersected in addition changing velocity. this:

cgrect frame = _ball.frame;  // change reflect top , bottom bool intersectstoppaddle = cgrectintersectsrect(cgrectinset(_ball.frame, -1, -1), _paddle1.frame); bool intersectsbottompaddle = cgrectintersectsrect(cgrectinset(_ball.frame, -1, -1), _paddle2.frame);  if (intersectstoppaddle || intersectsbottompaddle) {     if (intersectstoppaddle)  // move ball down         frame.origin.y += (_paddle1.frame.origin.y - _ball.frame.origin.y);     else // bottom paddle, move         frame.origin.y -= (_paddle2.frame.origin.y - _ball.frame..origin.y);      ballvelocity.y *= -1;     _ball.frame = frame; }

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