p->x = (float)x / (float)xsz - 0.5;
p->y = -(float)y / (float)xsz + 0.5 / aspect;
p->z = ((float)i / (float)num * 2.0 - 1.0) * 0.005;
p->x = (float)x / (float)xsz - 0.5;
p->y = -(float)y / (float)xsz + 0.5 / aspect;
p->z = ((float)i / (float)num * 2.0 - 1.0) * 0.005;