I found a problem in one of the if conditions that I gave you, it should be <= not just <
Also,your "if" have to go before the vert2,3,4 calculations like this:

Code:
var verts_per_row = 500;

if(closest_vertex<=verts_per_row)
{
   closest_vertex+=verts_per_row;
}

if(closest_vertex%verts_per_row==0)
{
   closest_vertex--;
}

var vert2 = closest_vertex + 1;
var vert3 = closest_vertex - verts_per_row; // 500 vertexes per row!!
var vert4 = closest_vertex - (verts_per_row-1);

"The more you know, the more you realize how little you know..."

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