+P6t = P5 + [ 0, outside_pushh - ourcirc_r*2 ];
+P7 = [ P6t[0] + (P6t[1] - P1[1]) / outside_pushslope,
+ P1[1] ];
+
+P3a = P3t + [ -outside_push_inadj, 0 ];
+P6a = P6t + [ -outside_push_inadj, 0 ];
+
+outside_push_inadj_slope = (P3t[1]-P4[1]) / (P6a[1]-P5[1]);