How to make object jump?

[X-0ut]

I've tried using both cpBodyApplyImpulse and cpBodyApplyForce to make an object jump upwards, but it allways moves sideways.
Is this the way I'm supposed to do this or is there a better way?

[slembcke]

Don't know why that would make the object move sideways.

I usually just do something like the following:

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body->v.y += 20.0f

[X-0ut]

Oh ok thanks, in the docs it says not to set those values explicitly so I did not bother trying - might want to update them.
I also had to make it so that the object only jumped when on land, which I did by using a collision pair function. (Maybe that might help someone in future, I don't know)

[slembcke]

Oh ok thanks, in the docs it says not to set those values explicitly so I did not bother trying - might want to update them.
I also had to make it so that the object only jumped when on land, which I did by using a collision pair function. (Maybe that might help someone in future, I don't know)

Setting the position constantly is generally a bad idea. Setting the velocity can be fine if you are careful (cpBodyApplyImpluse() does nothing special in this regard). The problem is when you do something like this:

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body->v.x = 100

Say that object hits a solid wall. The wall will stop it's velocity, but the next step it will get set back to 100. This means that the velocity will be flickering between 0 and 100 while the impulse solver is running. Anything else touching that object is likely to behave very oddly.

Yeah, a collision function is the only good way to do it. You will also want to use the collision normal to determine if the player is touching a wall, the ceiling, or the floor.

[X-0ut]

Thanks, it all worked out great