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Help?
Have you tried using some vertex groups?
this is very strange!
it appears to send a positive pulse whenever the ball hits any object that has the specified material on the first lot, and when it’s not the first it sends a negative pulse 
that also happens with the touch sensor 
@Raco he means 2 materials in one object. It works fine if the object had one material though (like your example)
Also, in order to determine whether the player can jump or not, I would suggest to use another method. A disadvantage with your method would be that every object needs more work to set the materials. It’s even a serious problem if you want to use rigid bodies in your game. Let’s say you have a box for your player to stand and jump on. If the box would have flipped sides the materials would have too.
I would suggest using a separate object attached to the player for collision. This is an example:
Attachments
FloorBox2.blend (74 KB)
Thanks ehabcharek. I can see now. This looks like a bug.
My god! Your a genius! I never thought of that! Do you mind if I totally steal your way of doing this? I’ll put you in the credits of whatever I make with this system.
Oh! and you could also change the size of the “ColFloor” depending on what level of slope you wanted the character to be able to jump off of! and if you wanted some object that the character couldn’t jump whilst standing on, you could make a collision sensor for that propriety, hit “invert”, and hook it up to the And controller!