how to predict physics trajectory of a sphere

Questions & Answers
1

Hey guys

I’m working on a game where I have to throw a bouncing ball on walls.
I have some sort of aiming assistance where I simply draw line from the current ball position to the raycast hit position
Then using the raycast hit normal, I compute the reflection vector and display another line starting from the hit position and following the reflection vector direction…
Anyway I’m sure you got my point…
This works perfectly, the raycast always returns me correct Hit point & Reflection vector

But on the physics side the ball doesn’t follow the same trajectory at all…
I’ve tried to turn off the gravity… same issue
I’ve also tried to use a point (instead of a sphere) by using a tiny radius on my sphere collider… same issue…

Even with a simple case where I throw the ball in the up direction, with a wall at a 45 degrees angle
The ball doesn’t bounce on a 135 degrees angle like the raycast does but something around 150…

Am I missing something obvious here ??

Thanks a lot for any kind of answers… I’m really stuck here and don’t write to write my own physics engine :wink:

2

It sounds like you’re headed in the right direction you’ll just need to tweak the physics settings of your ball to match your raycasting.

For instance you might want to minimise drag and angular drag on the ball, and play with the mass etc.

I hope that helps either that or I’m totally missing what you are trying to do :stuck_out_tongue:

3

if u want things to bounce nicely you should move them through script, just use the same ray trajectory to moveyour ball across. I did a project like this after seeing the disc battles in tron :wink: