for(float y = bbox.p1.y - cell_height; y < bbox.p2.y + cell_height; y += cell_height) {
for(float x = bbox.p1.x - cell_width; x < bbox.p2.x + cell_width; x += cell_width) {
int gridx = int(x / cell_width);
for(float y = bbox.p1.y - cell_height; y < bbox.p2.y + cell_height; y += cell_height) {
for(float x = bbox.p1.x - cell_width; x < bbox.p2.x + cell_width; x += cell_width) {
int gridx = int(x / cell_width);