Thanks,wabe.I must align corns plants in separate rows in a square field:one line of corns,one line of sand,one line of corns,one line of sand,etc. I want to use 2-3 corns plants- meshes(pz3 file)with differents positions with one ecosystem material.I have tried with a function but i think i don't really understand functions in Vue.May be with a map !...or finally place each one manually.. but i don't want too much polygones with a filed like that.