// -*- C -*-

hoopthick = 3;

hinnerrad = 15;
houterrad = hinnerrad + hoopthick;
hcentredist = 10;

blockdepth = 5;
blockwidth = hcentredist*2 + 6;

height = 20;

ziglen = hcentredist/2;

feedxgap = 5;

feedzgap = 5;

ribdepth = 2;
ribheight = 3;

module Oval(centredist, rad) {
  hull() {
    translate([-centredist/2,0,0]) circle(r=rad);
    translate([+centredist/2,0,0]) circle(r=rad);
  }
}  

module Hoop(){
  difference(){
    hull(){
      Oval(hcentredist, houterrad);
      translate([0, (blockdepth + hoopthick)/2 + hinnerrad])
	square([blockwidth,
		blockdepth + hoopthick],
	       center=true);
    }
    Oval(hcentredist, hinnerrad);
  }
}

module Positive(){
  translate([0,0, -height/2])
    linear_extrude(height=20)
    Hoop();
}

module Division(biggerpi) {
  xgap = feedxgap * biggerpi;
  zgap = feedzgap * biggerpi;
  mirror([0,0,1])
    translate([-(ziglen + xgap/2), -100, zgap/2])
    cube([100, 100, 10]);
}

module Ribs(){
  imax = ceil(height*2 / ribheight);
  for (i=[-imax:imax]) {
    hull(){
      translate([-ribdepth/2,
		 ribheight*i,
		 0])
	polygon([[0,          0],
		 [ribdepth, -ribheight],
		 [ribdepth, +ribheight]]);
      translate([50, 0])
	square([1, height*2], center=true);
    }
  }
}	    

module Demo(){
  //difference(){
  %  Positive();
  //  Division(0);
  //}
  Division(1);
}

Ribs();