private int getFirstIdenticalVertexId(Model model, int vertex) {
		int vertexId = -1;
		int x = model.verticesX[vertex];
		int y = model.verticesY[vertex];
		int z = model.verticesZ[vertex];
		for (int v = 0; v < vertexCount; v++) {
			if (x != verticesX[v] || y != verticesY[v] || z != verticesZ[v])
				continue;
			vertexId = v;
			break;
		}

		if (vertexId == -1) {
			verticesX[vertexCount] = x;
			verticesY[vertexCount] = y;
			verticesZ[vertexCount] = z;
			if (model.vertexSkins != null)
				vertexSkins[vertexCount] = model.vertexSkins[vertex];
			vertexId = vertexCount++;
		}
		return vertexId;
	}