+ register double xmid, ymid;
+ double x1, y1, x2, y2, x3, y3, x4, y4;
+
+ wx_clear_stack();
+ wx_spline_push(a1, b1, a2, b2, a3, b3, a4, b4);
+
+ while (wx_spline_pop(&x1, &y1, &x2, &y2, &x3, &y3, &x4, &y4)) {
+ xmid = (double)half(x2, x3);
+ ymid = (double)half(y2, y3);
+ if (fabs(x1 - xmid) < THRESHOLD && fabs(y1 - ymid) < THRESHOLD &&
+ fabs(xmid - x4) < THRESHOLD && fabs(ymid - y4) < THRESHOLD) {
+ wx_spline_add_point((double)wx_round(x1), (double)wx_round(y1));
+ wx_spline_add_point((double)wx_round(xmid), (double)wx_round(ymid));
+ } else {
+ wx_spline_push(xmid, ymid, (double)half(xmid, x3), (double)half(ymid, y3),
+ (double)half(x3, x4), (double)half(y3, y4), x4, y4);
+ wx_spline_push(x1, y1, (double)half(x1, x2), (double)half(y1, y2),
+ (double)half(x2, xmid), (double)half(y2, ymid), xmid, ymid);
+ }
+ }