how can i jump with a simple code in a 3d plataform game? i've tried the aum 79 but i couldnt make it work, (no animation, just a block model)

The basic idea is that when you push a button it needs to increase the Z of the entity. To practice just have it move the charter's Z position while the key is pressed. Use no Gravity in this experiment. Then have it decrease the Z as gravity normally would an use collision detection.

While I've not looked at AUM 79 one problem you might have is that your character could be so big that the bit that is jumping by could nothing for that size. Try increasing the amount you jump by.

var gravity = 9.8;
var jump = 0;
var mumpspeed = 5;

function main(){
while(1){
if(key_cuu && player hitting platform){
jump = 1;
}
else if(player hitting platform){
jump = 0;
}

if(jump){
player.z += jumpspeed;
}

player.z -= jumpspeed;
}
}

It should be along the lines of that. Look at it, experiment, and modify to fit your uses.

thats very simple, i have some experience on that, the problem is to make the z to decrease after the character has areached a certain altitude...
and no problem with the character size, its just the guard model that comes with the 3dg

Think of how gravity works. When you jump gravity doesn't stop, it is simply overwhelmed by the amount of force you used to push yourself off the ground, however it is still acting on you, slowing you down until you stop moving upwards. For a fraction of a second you are actually still in the air. Then you start to come down as only gravity is acting on you.

You will need to do a lot of similar thinking when you program.

So a good way is to set an "up" movement on you Z and have the gravity subtract from it. A good way to do that is set one of the skills as the gravity and have it pull the player down all the time and have a function check on it's gravity and if it gets to high thanks to the jump have it lower it slowly until you get back to the correct negative z.

i set the gravity by adding -2 at the c_move instruction and it works fine. the problem is when i do "if(key...) my.z +..."
the player keeps going upwards till i release the key, and if i use "on_key... = jump" it jumps but it doesnt wait until the player touches the floor, and i want it to be able to jump only when its on the floor, not when its in the air.

Check what I said about the gravity var. Set a skill for your gravity and use that in your c_move. Again, you add this number once.

Now you'll need another var or bool or whatever. When you push the space bar check to see if that var is true. If it is not then set it to true and do the jump. When that number reaches negative 2 or whatever have the bool set to false.