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How to make an object stick to the surface?
Hello
I'm working on a pinball project, and my ball sometimes flies out of the board.
I tried making an invisible plane above the board with a collider but then I cant make ramps that go up, same problem when I freeze the Y position of the ball.
Thanks for reading.
Answer by AlwaysSunny · Apr 05, 2015 at 07:59 PM
Small, high-velocity objects have a hard time respecting the common sense rules of physics. If you make a wall, you expect it to prevent passage; yet get a small object going fast enough in the right conditions and it can slip right through. This is a very well-documented issue, sometimes called "ghosting" or "clipping".
There are many factors to consider, and I'm not personally aware of any article or guide that details each and every consideration.
A pinball game is physics-intensive, so consider decreasing the project's physics timestep. This trades performance for accuracy; depending on the target device, this may be suitable. Try the different physics modes (interpolate, extrapolate) on the pinball itself to see if you get more stable results. Using the strongest possible geometry in your environment design is also important; there's info to be found about this too.
If all else fails, you can enforce your own physics rules by hand-coding some kinematics; all the great examples of physics in video games take some "artistic liberties" with realism in favor of stability.
I just re-read your question more carefully and better understood the issue. All pinball machines have a clear top to prevent accessing the board; In a true 3D pinball video game, there's nothing stopping you from having an invisible top. Just make it slightly greater than one ball diameter higher than the highest point on the board.
The direct answer to your question (make the object stick to the surface) will involve hand-coded kinematics and raycasts to achieve and maintain a specific distance between the ball and the surface beneath it.
I made an invisible cube above the board with a collider. It took me a while to do it above the ramps but, this works perfectly. Thanks!
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