// -*- C -*-

main_height = 95;

spike_top_width = 21.04;

spike_botpos_height = 9.5;
spike_botpos_width = 11.68;

topwall_width = 1.5;

// calculated

main_width = spike_top_width + topwall_width*2;

module NegativePlan(){
  x4z =
    (spike_top_width - spike_botpos_width) /
    (main_height - spike_botpos_height);

  x0 = (spike_botpos_width - x4z * spike_botpos_height)/2;
  x1 =  spike_top_width/2;
  z1 = main_height;

  polygon([[ x0, -5],
	   [ x0, 0],
	   [ x1, z1],
	   [ x1, z1+5],
	   [-x1, z1+5],
	   [-x1, z1],
	   [-x0, 0],
	   [-x0, -5]]);
}

module PositivePlan(){
  w = main_width;
  translate([ -w/2, 0 ])
    square([ w, main_height ]);
}

module PlanTest(){
  linear_extrude(height=2.0){
    difference(){
      PositivePlan();
      NegativePlan();
    }
    difference(){
      circle(r = spike_botpos_width/2 + 5);
      circle(r = spike_botpos_width/2);
      translate([-50, 0]) square([100,50]);
    }
  }
  linear_extrude(height=4.0){
    difference(){
      translate([ -main_width/2, 0 ]) square([ main_width, 2 ]);
      NegativePlan();
    }
  }
}

PlanTest();