My 3d tennis game is currently more like a 2d tennis game as my ball never uses gravity for its y values at the minute, it moves only left and right and forward and back, not up and down. I have the collision detection pretty much sorted for all the objects and the ball stays within its confines. As soon as i introduce gravity my ball is apparently colliding with floor level even though i am not checking for a collision like this :s

and as soon as it bounds of the floor it just flies up in the air and doesnt come back down, now my understanding is that gravity is a pretty simple effect to achieve even in 3d, just a case of decreasing the y values of an object by however many units per second or something. This is exactly how i implemented it



then when the ball reaches floor level its y increases by a certain amount to give the bounce effect
should work right :s
i have even tried hard coding a max y for the ball that i thought might bring it back down, i even tried some boolean variables for climbing and falling, i have no clue why it doesnt want to work
any help is greatly appreciated, im using c++ and opengl

thanks

http://en.wikibooks.org/wiki/FHSST_Physics:Index

its not the physics i dont understand its my code, thanks though.

i know the physics, its gravity.

I will solve it hopefully soon, my game is leaking like a bucket as well and its gotta be handed in in 3 weeks :s

I only posted it because of this:


The bounce (assuming it's perfectly elastic, and that I understand what you're talking about ) should preserve the speed of the ball and just change it's direction.

Gravity should just be used to accelerate objects downwards.

Bounces should be based upon collisions. If your court is a level plane at y=0 then you can test for when the ball's y=0, and flip the sign of it's vertical speed.

sorry that was my bad explanation :s

what i meant was that gravity would decrease the y and then the collision would add to the y by a certain amount before the gravity would take it back down again. I just dont get it though i have implemented this tons of times with no problems but this just wont do it, and i havnt even implemented the floor collision yet :s very odd.

and im not typecasting my objects for collisions detection which might explain the floor detection, ill ask my lecturer on monday, cheers for the help tho

It's okay, physics in games can be confusing. It's one thing to solve a problem for a fixed scenario (like a practice problem in class), but writing a solution that can dynamically change based upon the input is hard.

This post has been edited by Tom9729: 28 Jun, 2008 - 03:52 PM