fix: character controller: walls less likely to trigger ground detection

[Vrixyz]

Context

While trying out dimforge/bevy_rapier#476 ; I noticed I could jump when hitting walls (particularly on the junction of 2 walls).

Bug analysis

When printing the normal dot value, I had this value in air: 1.7037166e-5 (hitting a wall perfectly perpendicular)

The current epsilon being 1.0e-5 ; this dot check is true, then is_grounded is true, and the character can jump in the example from dimforge/bevy_rapier#476.

Solution decription

I think it makes sense to relax this epsilon ; alternatively we could:

• reuse the slope authorized for the character
• or really pump that value, and/or normalize it
• make it configurable

But that first fix is probably an easy sufficient fix ?

I'm wondering if this has anything to do with scaled transforms ?

[sebcrozet]

For the record, bumping the epsilon to 1.0e-3 means that for the controller to be grounded, the angle between the contact normal and the up vector has to be smaller than 89.9427042 degrees (instead of 89.999427 when the epsilon was 1.0e-5). That sounds reasonable.