$fn=64;

// --- Parameters ---
stand_width = 180;     // Total width of the stand
stand_depth = 160;     // Total depth of the base
stand_height = 220;    // Total height of the stand
wall = 16;             // Thickness of structural parts
lip_depth = 45;        // Depth of the canvas slot (fits thick gallery canvases)
lip_height = 40;       // Height of the front retaining lip
tilt = 15;             // Tilt angle of the backrest (degrees)
leg_width = 20;        // Width of the solid left and right side legs

// Derived values
canvas_start = wall;
back_start = canvas_start + lip_depth;
eps = 0.05;            // Small overlap to ensure manifold geometry

// 2D Profile of a single leg
module 2d_leg() {
    union() {
        // Front lip
        square([wall, lip_height]);
        translate([wall/2, lip_height]) circle(d=wall);

        // Base
        square([stand_depth, wall]);

        // Angled backrest
        translate([back_start, wall])
        rotate([0, 0, -tilt])
        square([wall, stand_height - wall]);

        // Structural gusset (reinforcement triangle)
        hull() {
            translate([back_start, wall])
            square([wall, 0.1]);

            translate([back_start, wall])
            rotate([0, 0, -tilt])
            translate([0, (stand_height - wall) * 0.5])
            square([wall, 0.1]);

            translate([stand_depth - wall, 0])
            square([wall, wall]);
        }
    }
}

// Extrude and orient the 2D profile into 3D
module leg_3d() {
    rotate([90, 0, 90])
    linear_extrude(height = leg_width)
    2d_leg();
}

// Generates a perfectly flush crossbar with a flat bottom for 3D printing bridges
module backrest_crossbar(z_bottom, h) {
    intersection() {
        // Horizontal bridging block
        translate([leg_width - eps, 0, z_bottom])
        cube([stand_width - 2*leg_width + 2*eps, stand_depth, h]);

        // Solid backrest projection
        translate([0, back_start, wall])
        rotate([-tilt, 0, 0])
        cube([stand_width, wall, stand_height * 2]);
    }
}

// Assemble the complete stand
module canvas_stand() {
    // Left Leg
    leg_3d();

    // Right Leg
    translate([stand_width - leg_width, 0, 0])
    leg_3d();

    // 1. Front Lip Crossbar
    translate([leg_width - eps, 0, 0])
    cube([stand_width - 2*leg_width + 2*eps, wall, lip_height]);

    // Front Lip Rounded Top
    translate([leg_width - eps, wall/2, lip_height])
    rotate([0, 90, 0])
    cylinder(h=stand_width - 2*leg_width + 2*eps, d=wall);

    // 2. Base Front Crossbar (Canvas Rest)
    translate([leg_width - eps, wall - eps, 0])
    cube([stand_width - 2*leg_width + 2*eps, lip_depth + 2*eps, wall]);

    // 3. Base Rear Crossbar
    translate([leg_width - eps, stand_depth - wall, 0])
    cube([stand_width - 2*leg_width + 2*eps, wall, wall]);

    // 4. Backrest Top Crossbar (Flat bottom for clean bridging)
    backrest_crossbar(stand_height - 35, 20);

    // 5. Backrest Middle Crossbar (Flat bottom for clean bridging)
    backrest_crossbar((stand_height + wall)/2 - 10, 20);
}

// Render the model
canvas_stand();