GML how to make perfect tileset collision?

[duran can]

I'm trying to platform game, using new tileset system. How can i do perfect collision with tileset?

sw=bbox_right - bbox_left+1;
sh=bbox_bottom - bbox_top+5;
//bottom collision
if ( tilemap_get_at_pixel(map_id,x,y+sh/2)!=0 
|| tilemap_get_at_pixel(map_id,x+sw/2,y+sh/2)!=0 
|| tilemap_get_at_pixel(map_id,x-sw/2,y+sh/2)!=0){
move_contact_all(direction,1);
speed=0;
vspeed=0;
hspeed=0;
}else{direction=270;speed=grv;}

thanks for all replies

 

[SeraphSword]

Shaun Spalding has a pretty straightforward tutorial on it:

 

[pgvago]

Thanks Duran Can.
Your code actually helped me to solve my problem.

Pietro.