include <MCAD/math.scad>;
include <lib.scad>;

stock_color = "#aaa4";

bushing_od = 12;
bushing_id = 8;
bushing_len = 8;

nema17_face = 42.3;

module colorize(colorname) {
  if (use_colors) {
    color(colorname) union() { children(); }
  } else {
    children();
  }
}

module bushing() {
  bom_item(printable=false, label="Bushing");
  colorize(stock_color) render() {
    difference() {
      cylinder(d = bushing_od, h = bushing_len);
      translate([0,0,-1])
	cylinder(d = bushing_id, h = bushing_len + 2);
    }
  }
}

// located with the shaft in +z, face on the XY plane 
module nema17(depth = 23.5) {
  bom_item(printable=false, label="NEMA-17 stepper motor");
  face = 42.3;
  screw_pitch = 31 / 2;
  color(stock_color)
    render()
  difference() {
    union() {
      translate([-face/2, -face/2, -depth])
	cube([face, face, depth]);
      translate([0,0,-1]) {
	cylinder(d=22, h=2+1);
	cylinder(d=5, h=22+1);
      }
    }
    translate([1.25, -5, 4])
      cube([10, 10, 20]);

    // screw holes
    for (x = [-screw_pitch, screw_pitch],
	   y = [-screw_pitch, screw_pitch]) {
      translate([x,y,-10])
	cylinder(d=5,h=20);
    }
  }

}

// belts and pulleys
belt_pitch = 2; // 2mm tooth width for GT2 = 2mm pitch
belt_width = 6;
belt_thickness = 1.38;
belt_pld = 0.254; // distance between line of fixed length and tips of gear teeth
belt_backing = 0.63 - belt_pld;
tooth_height = 0.75;

pulley_od = 13;
pulley_clearance_rad = pulley_od / 2 + 2.5;

module pulley(teeth, lrim, urim, belt_width, shaft=5, toothed=true, od = 0) {
  bom_item(printable=false, label=str(
    toothed ? "pulley(" : "idler(",
    "teeth=", teeth, ", ",
    "flange1=", min(lrim, urim), "mm, ",
    "flange2=", max(lrim, urim), "mm, ",
    "channel=", belt_width, "mm, ",
    "shaft=", shaft, "mm",
    ")"
  ));
  nominal_rad = belt_pitch * teeth / TAU;
  inner_rad = nominal_rad - belt_pld;
  outer_rad = (od > 0) ? od / 2 : nominal_rad +  belt_backing;
  minor_rad = inner_rad - tooth_height;
  mid_rad = inner_rad - tooth_height / 2;
  idler_rad = nominal_rad - belt_backing;

  dtheta = 180 / teeth;

  tooth_points = [
    for (i = [1:1:teeth])
    let (theta = i * 360 / teeth)
    each [
      [sin(theta) * minor_rad, cos(theta) * minor_rad],
      [sin(theta) * inner_rad, cos(theta) * inner_rad],
      [sin(theta + dtheta) * inner_rad, cos(theta + dtheta) * inner_rad],
      [sin(theta + dtheta) * minor_rad, cos(theta + dtheta) * minor_rad]
    ]
  ];

  //echo([each [0:1:teeth]]);

  //echo(tooth_points);

  colorize(stock_color)
  render()
  difference() {
    union() {
      cylinder(r=outer_rad, h=lrim);
      translate([0,0,lrim])
      if (toothed) {
        linear_extrude(belt_width)
        polygon(tooth_points, convexity = teeth * 2 + 4);
      } else {
        cylinder(r = idler_rad, h = belt_width);
      }

      translate([0,0,lrim + belt_width])
      cylinder(r=outer_rad, h=urim);
    }

    translate([0,0,-1])
    cylinder(d=shaft, h=belt_width + lrim + urim + 2);
  }
}

idler_zmargin = [ 6.4 / 2 + 1.05, 6.4 / 2 + 1.05 ];

module idler(height=0, toothed=false) {
  // pulley(20, 1.05, 1.05, 6.4, toothed=toothed, od=18);
  translate([0,0, height-idler_zmargin[0]])
  pulley(16, 1.05, 1.05, 6.4, shaft=3, toothed=toothed, od=13);
}

active_pulley_zmargin = [ 9.5, 4.5 ];

module active_pulley(height=0) {
  translate([0,0,-active_pulley_zmargin[0] + height])
  pulley(16,6,1,7, od=13);
}

// required distance between centers of pulley and idler for an S-bend with right angles.
pulley_sbend_offset = (9.5 + 9.7) / 2 + 0.63;

//!pulley(12, 6, 2, toothed=false);