ポリラインを平面へ投影する

//
// ポリラインをYZ平面に投影する
// RunOver: Primitives
//
int pts[] = primpoints(0, @primnum);

float sum = 0;
for(int i = 0; i < len(pts); i++)
{
    vector pos = point(0, "P", pts[i]);
    if(i == 0)
    {
        setpointattrib(0, "P", pts[i], set(0, pos.y, 0));
    }
    else
    {
        vector prev = point(0, "P", pts[i-1]);
        vector diff = pos - prev;
        sum += length(set(diff.x, 0, diff.z));
        setpointattrib(0, "P", pts[i], set(0, pos.y, sum));
    }
}

//
// ポリラインをXY平面に投影する
// RunOver: Primitives
//
int pts[] = primpoints(0, @primnum);

float sum = 0;
for(int i = 0; i < len(pts); i++)
{
    vector pos = point(0, "P", pts[i]);
    if(i == 0)
    {
        setpointattrib(0, "P", pts[i], set(0, pos.y, 0));
    }
    else
    {
        vector prev = point(0, "P", pts[i-1]);
        vector diff = pos - prev;
        sum += length(set(diff.x, 0, diff.z));
        setpointattrib(0, "P", pts[i], set(sum, pos.y, 0));
    }
}