I'm working on a 2D iPhone game using Corona (Trial version, so I can't use their forums). The game involves the character falling through the sky, and I'm trying to implement a "double jump" for the character, for him to be able jump up while falling. I'm using Corona's physics library to have the character fall, and so far the best method of having him jump is using the vertical impulse method
object:applyLinearImpulse(0, -0.4, object.x, object.y)
The problem I face is that when the character is just starting out (vertical velocity is low), he jumps really high, and when he's been falling for a while (vertical velocity is high), the jump is negligible. I'm guessing that the best solution is to use some sort of equation with the velocity as input to make the jump the same regardless of velocity, but I can't figure out what that equation would be.
Okay, so that's all my thoughts. The end question is, how exactly do you implement a double jump with physics? Is there a proper equation for my problem? Should I take a different approach? It's been done before in games like Smash Bros, so there's a repeatable solution, right?