How to accurately detect collision?

Question

So I had a throwable fire grenade in my game that will bounce off the wall and explode when touching the ground. For my grenade, I set the rigidbody's collision detection to continuous and have a boxcast under it to check if it touches the ground. But sometimes when it moved so fast it would bounce back instantly in the next frame so my boxcast wouldn't work.

First frame: (the red box below the grenade is the boxcast, the grenade is falling) alt text Next frame: (the grenade bounce back off without actually touch the ground, so the boxcast isn't triggered)

Answer 1

Best Answer

Answer by Long2904 · Aug 06, 2020 at 06:17 AM

Decrease the fixed time step to something like 0.01 or 0.005 and change the yield return null to yield return WaitForFixedUpdate().

Add comment · Share

Answer 2

Answer by tuinal · Aug 04, 2020 at 03:38 AM

Simple option in edit>project settings>physics reduce 'fixed time step'. This runs the physics simulation more quickly at the cost of performance.

I think the best solution is to ditch the boxcast and use OnCollisionEnter2D instead. In OnCollisionEnter2D, if you want it to only explode when it hits the floor, do if(Vector2.Angle(Vector2.Up, collision.contacts[0].normal)<10f); or similar.

Add comment · Show 1 · Share

Long2904 · Aug 04, 2020 at 12:43 PM 0

Share

@tuinal Firstly, I thought the fixed time step is for the fixed update and my boxcast got called and updated in a coroutine that yield return null so I don't think this will fix anything. Secondly, I create and access the grenade gameobject through code (from another gameobject) in runtime so access to its update or OnCollsionEnter2D function is not possible. Do you have any other ideas? Edit: Also the timestep setting is in Time, not Physics, and I'm currently using Physics2D.

How to accurately detect collision?

2 Replies

Your answer

Follow this Question

Related Questions