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Catmull–Clark subdivision surface: Difference between revisions
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For edges and vertices not next to a hole, the standard algorithm from above is used.
=={{header|C}}==
Only the subdivision part. The [[Catmull–Clark_subdivision_surface/C|full source]] is way too long to be shown here.
<lang c>vertex face_point(face f)
{
int i;
vertex v;
if (!f->avg) {
f->avg = vertex_new();
foreach(i, v, f->v)
if (!i) f->avg->pos = v->pos;
else vadd(f->avg->pos, v->pos);
vdiv(f->avg->pos, len(f->v));
}
return f->avg;
}
#define hole_edge(e) (len(e->f)==1)
vertex edge_point(edge e)
{
int i;
face f;
if (!e->e_pt) {
e->e_pt = vertex_new();
e->avg = e->v[0]->pos;
vadd(e->avg, e->v[1]->pos);
e->e_pt->pos = e->avg;
if (!hole_edge(e)) {
foreach (i, f, e->f)
vadd(e->e_pt->pos, face_point(f)->pos);
vdiv(e->e_pt->pos, 4);
} else
vdiv(e->e_pt->pos, 2);
vdiv(e->avg, 2);
}
return e->e_pt;
}
#define hole_vertex(v) (len((v)->f) != len((v)->e))
vertex updated_point(vertex v)
{
int i, n = 0;
edge e;
face f;
coord_t sum = {0, 0, 0};
if (v->v_new) return v->v_new;
v->v_new = vertex_new();
if (hole_vertex(v)) {
v->v_new->pos = v->pos;
foreach(i, e, v->e) {
if (!hole_edge(e)) continue;
vadd(v->v_new->pos, edge_point(e)->pos);
n++;
}
vdiv(v->v_new->pos, n + 1);
} else {
n = len(v->f);
foreach(i, f, v->f)
vadd(sum, face_point(f)->pos);
foreach(i, e, v->e)
vmadd(sum, edge_point(e)->pos, 2, sum);
vdiv(sum, n);
vmadd(sum, v->pos, n - 3, sum);
vdiv(sum, n);
v->v_new->pos = sum;
}
return v->v_new;
}
model catmull(model m)
{
int i, j, a, b, c, d;
face f;
vertex v, x;
model nm = model_new();
foreach (i, f, m->f) {
foreach(j, v, f->v) {
_get_idx(a, updated_point(v));
_get_idx(b, edge_point(elem(f->e, (j + 1) % len(f->e))));
_get_idx(c, face_point(f));
_get_idx(d, edge_point(elem(f->e, j)));
model_add_face(nm, 4, a, b, c, d);
}
}
return nm;
}</lang>
=={{header|J}}==
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