Wireframe Chair

/* [Global] */

// Width at the armrests
chair_width = 580; // [400:10:900]
// Total chair depth
chair_depth = 600; // [400:10:900]
// Front seat rim height
seat_height = 450; // [300:10:600]
// Total chair height
total_height = 820; // [600:10:1000]

/* [Frame Profile] */
// Base thickness of the struts
strut_size = 22; // [10:1:40]
// Flatness ratio (smaller = flatter)
flatness = 0.45; // [0.1:0.1:1.0]
// Quality of the rounded joints
quality = 32; // [16:8:64]

/* [Colors] */
frame_color = [0.65, 0.65, 0.65];

/* [Hidden] */
$fn = quality;
w = chair_width;
d = chair_depth;
sh = seat_height;
th = total_height;
r = strut_size / 2;

// Vertex Mapping [X, Y, Z]
vertices = [
    // 0-3: FLOOR BASE
    [ w*0.48, -d*0.4,  0], [ -w*0.48, -d*0.4,  0], [ -w*0.42,  d*0.35, 0], [ w*0.42,  d*0.35, 0],
    
    // 4-9: SEAT RIM (8 and 9 are critical transitions)
    [ w*0.35, -d*0.35, sh], [ -w*0.35, -d*0.35, sh], [ -w*0.48, -d*0.05, sh+80], [ w*0.48, -d*0.05, sh+80], [ -w*0.25,  d*0.25, sh+20], [ w*0.25,  d*0.25, sh+20],
    
    // 10: SEAT CENTER
    [ 0, -d*0.05, sh-20],
    
    // 11-13: BACKREST TOP
    [ -w*0.35,  d*0.45, th-30], [ w*0.35,  d*0.45, th-30], [ 0, d*0.5, th],
    
    // 14: BACKREST CENTER
    [ 0, d*0.48, sh+220],
    
    // 15: FRONT MID RIM
    [ 0, -d*0.35, sh],
    
    // 16-17: LEG X-INTERSECTIONS
    [ w*0.33, -d*0.05, sh*0.5], [ -w*0.33, -d*0.05, sh*0.5]
];

// Structural categorization
edges_legs = [[0, 4], [1, 5], [2, 8], [3, 9], [0, 3], [1, 2], [0, 16], [3, 16], [4, 16], [9, 16], [1, 17], [2, 17], [5, 17], [8, 17], [0, 15], [1, 15]];
edges_seat = [[4, 15], [5, 15], [5, 6], [6, 8], [8, 9], [9, 7], [7, 4], [4, 10], [5, 10], [6, 10], [8, 10], [9, 10], [7, 10], [15, 10]];
edges_back = [[8, 11], [9, 12], [11, 13], [12, 13], [8, 14], [9, 14], [11, 14], [12, 14], [13, 14], [6, 11], [7, 12]];

module oriented_node(idx, type) {
    p = vertices[idx];
    translate(p) {
        // Nodes 6-9 are transitions where seat (Z-flat) meets backrest (Y-flat)
        // We use a less flattened node here to prevent ends sticking out
        if (idx == 6 || idx == 7 || idx == 8 || idx == 9) {
            scale([1.15, 0.8, 0.8]) sphere(r = r);
        } else if (type == "backrest") {
            scale([1.1, flatness, 1.1]) sphere(r = r);
        } else {
            scale([1.1, 1.1, flatness]) sphere(r = r);
        }
    }
}

module oriented_strut(i1, i2, type) {
    hull() {
        oriented_node(i1, type);
        oriented_node(i2, type);
    }
}

module build_chair() {
    color(frame_color) {
        // Render Struts
        for (e = edges_legs) oriented_strut(e[0], e[1], "legs");
        for (e = edges_seat) oriented_strut(e[0], e[1], "seat");
        for (e = edges_back) oriented_strut(e[0], e[1], "backrest");
        
        // Render Nodes at all intersections for seamless miter joints
        for (i = [0:17]) {
            // Determine type for nodes that aren't transition nodes
            t = (i >= 11 && i <= 14) ? "backrest" : "seat";
            oriented_node(i, t);
        }
    }
}

build_chair();