/**
 * tub.scad
 *
 * The tub of a microcar.
 */

include <BOSL2/std.scad>

$fn = $preview ? 32 : 256;

a_pillar_y = -400;  // y location of face of 'A' pillar
bb_height = 274;    // internal height of battery box
bb_width = 260;     // internal width of battery box

/*****************************************************
 * the 'cowl' is the near-horizontal panel which the
 * bottom of the windscreen is mounted to. In practice
 * this probably slopes down forward, but for the
 * moment I'm making the simlifying assumption that it
 * is horizontal.
 ****************************************************/

// slope of the cowl
cowl_angle = -70;
// maximum height of the cowl (at the A pillar)
cowl_height = 450;  

floor_length = 1100;
floor_width = 1500;

/*****************************************************
 * TODO: I need to calculate the lengths of everything
 * which bonds to the front or rear bulkhead from the
 * layback angles, but I'm being lazy for now
 ****************************************************/
// angle of the front bulkhead to vertical
layback_angle_f = 30;
// angle of the rear bulkhead to vertical
layback_angle_r = 50;

sheet_thickness = 8;
sill_max_height = bb_height;
sill_min_height = 125;
sill_width = 150;

module battery_box_side( floor_length = 1100) {
    fhl = (floor_length/2);
    top_hlf = (bb_height * tan(layback_angle_f)) + fhl;
    top_hlr = (bb_height * tan(layback_angle_r)) + fhl;
    rotate([90, 0 , 0])
        linear_extrude( height=sheet_thickness) {
            polygon([[ 0 - fhl, 0], 
                [ fhl, 0], 
                [ top_hlr, bb_height],
                [ 0 - top_hlf, bb_height]]);
        }
}

module battery_box( floor_length = 1100) {
    top_hl = 800; // calculate this later
    hbbw = bb_width/2;
    bias = (layback_angle_f == layback_angle_r) ? 0 : bb_height * ( tan(layback_angle_r) - tan(layback_angle_f))/2;
    
    translate([0, hbbw, 0])
        battery_box_side( floor_length);
    translate([0, 0 - (hbbw + sheet_thickness), 0])
        battery_box_side( floor_length);
    translate([0, 0 - hbbw, 0])
        cube([sheet_thickness, bb_width, bb_height]);
    translate([bias, 0 - sheet_thickness, bb_height])
        cube([floor_length + (bb_height * tan(layback_angle_f)) +
        (bb_height * tan(layback_angle_r)), bb_width + (sheet_thickness * 2),
            sheet_thickness],
        center = true);
}

module sill( floor_length = 1100) {
    cr = 5000;
    fhl = (floor_length/2);
    top_hl = fhl + (cowl_height * tan(layback_angle_f)); 
    top_hlr = fhl + (sill_max_height * tan(layback_angle_r));
    difference() {
        rotate([90, 0 , 0])
            linear_extrude( height=sill_width) {
                polygon([[ 0 - fhl, 0], 
                    [ fhl, 0], 
                    [ top_hlr, sill_max_height],
                    [ 0, sill_min_height],
                    [ a_pillar_y, sill_min_height],
                    [ a_pillar_y, cowl_height],
                    [ 0 - top_hl, cowl_height]]);
            }
        rotate([-3, 0, 0])
            translate([0, cr - (sill_width/2), 0])
                cylinder( h = cowl_height,
                r = cr);
    }
}

module front_bulkhead() {
    e = cowl_height / cos(layback_angle_f);
    
    translate([ 0 - floor_length/2, 0 -floor_width/2, 0])
    rotate([0, 0- layback_angle_f, 0])
    cube([sheet_thickness, floor_width, e]);
}

module rear_bulkhead() {
}
    
module tub(fl=floor_length, fw=floor_width, st=sheet_thickness,
        sw=sill_width) {
    cube([fl, fw, st],
            center=true);
    battery_box();

    translate([0, ( fw/2) + (sw/2), 0])
        sill();

    mirror([0, 1, 0])
        translate([0, 
            ( fw/2) + (sw/2), 0])
            sill();

    front_bulkhead();
        
    rear_bulkhead();
}

// tub();