Store C++ Array outside loop

Question

I have a problem when trying to tesselate a polygon using GLU. The vertex callback always calls back with the last vertex defined by gluTessVertex. It seems as though the values stored in GLdouble v[3] are getting GC'd in each iteration of the for loop. How can I store each GLdouble v[3] so it does not get GC'd?

for(int i = 0; i < vtxcnt; i++)
{
    float lon = dbls[i * 2];
    float lat = dbls[(i * 2)+1];
    GLdouble v[3] = {lon, lat, 0.0f};
    gluTessVertex(tess, v, v);
}

* EDIT: This seems to fix the problem... *

GLdouble *vtxs = new GLdouble[vtxcnt * 3];

for(int i = 0; i < vtxcnt; i++)
{
    lon = dbls[i * 2];
    lat = dbls[(i * 2)+1];

    vtxs[(i * 3) + 0] = (double)lon;
    vtxs[(i * 3) + 1] = (double)lat;
    vtxs[(i * 3) + 2] = (double)0;
    gluTessVertex(tess, &vtxs[(i * 3) + 0], &vtxs[(i * 3) + 0]);
}

Standard C++ doesn't have a garbage collector at all.

Mat
– Mat

2012-09-22 16:15:28 +00:00
Commented Sep 22, 2012 at 16:15 — Mat
– Mat, Commented Sep 22, 2012 at 16:15

gexicide · Accepted Answer · 2012-09-22 16:15:59Z

1

gluTessVertex only stores the vertex pointer. The pointer must stay valid until the tesselation is performed. This is not the case in your code, so it fails.

answered Sep 22, 2012 at 16:15

gexicide

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