Double jump bug

[apaatsio]

It's possible to perform a "double jump". It seems that sometimes when you press the Up key right at the peak of the first jump, it performs a second jump. I'm sure this is not the desired behavior. This happens maybe about 1 out of 20 times when I try to deliberately do it.

Excalibur: 0.24.4
sample-platformer: 717c7a1

[eonarheim]

@apaatsio Good find! Double jumps definitely not intentional.

Must be something odd about https://github.com/excaliburjs/sample-platformer/blob/master/src/bot.ts#L59 allow the jump to be registered https://github.com/excaliburjs/sample-platformer/blob/master/src/bot.ts#L99

[eonarheim]

Okay, this is a subtle issue but I believe this is because the collision resolution runs after actor update.

Immediately after the jump the actor update is complete and the jump impulse won't be applied to position until the next frame, so still colliding.

In the same frame, collision is processed and the actor geometry is still intersecting so onGround is set back to true, making a double jump possible in the very next frame.

Potential solutions:

• Switch to onPreUpdate to ensure impulse is processed the same frame as collisions
• Shift the actor pos.y up to keep from re-colliding with the floor the same frame as the jump

[eonarheim]

@apaatsio I switched to onPreUpdate seems to do the right thing, thanks for the find!