hey Superku,

youre right ! It works when I call c_updatehull after creating.

Code:
ENTITY* e = ent_create("terrain.hmp", vector(100,0,0),NULL);
        set(e,POLYGON);
        c_updatehull(e,0);


I thought on object creation the engine does an intern c_updatehull.

Seems not to be. Wow! it works now.

Thank you Superku for your time and the golden hint.

"Make a great game or kill it early" (Bruce Shelley, Ensemble Studios)