Hihoo, i want that my player only can jump when he is touching ground, not the walls for example. Only when the lowest point of the modell touches another block or modell he can jump. How i can do this ?

Something like this would be good:

if(collision at position (x,y, z - 2/height of playermodel)
...

Do a c_trace from the player to a position under his feet, check if there is anything and maybe how far away it is, this will give you a clue about if the player touches the ground or not.

Xarthor is right. Use vec_for_vertex to get the position of a vertex on player's feet, and then trace from there below it.

Interesting way to check collisions Thx !

You are welcome. This is the best way of doing the things because it takes into account the actual animation frame, not just the origin of the model.