final void setCenter(int iModel) {
		Point3f center = new Point3f(0, 0, 0);
		int iptlast = -1;
		int ipt = 0;
		int n = 0;
		for (int i = polygonCount; --i >= 0;) {
			if (iModel >= 0 && i != iModel)
				continue;
			iptlast = -1;
			for (int iV = polygonIndexes[i].length; --iV >= 0;) {
				ipt = polygonIndexes[i][iV];
				if (ipt == iptlast)
					continue;
				iptlast = ipt;
				center.add(vertices[ipt]);
				n++;
			}
			if (n > 0 && (i == iModel || i == 0)) {
				center.scale(1.0f / n);
				break;
			}
		}
		if (iModel < 0) {
			ptCenter = center;
		}
		else {
			ptCenters[iModel] = center;
		}
	}