// ====================================================================
//  Two-part self-watering flower pot, designed for PETG
// ====================================================================
//  OUTER pot : watertight reservoir cup. Spiral ridges on the outside, smooth tapered inside, with a conical seat at the rim.
//  INNER pot : planter with drainage holes. Its conical underside rests on the seat, which leaves a water reservoir underneath. It lifts straight out (tapered fit, no snap that can jam).
// ====================================================================

/* [What to render] */
part = "print"; // [print:Both parts laid out for printing, outer:Outer pot only, inner:Inner pot only, assembly:Assembled preview, section:Assembled cut-away preview]

/* [Main dimensions (mm)] */
// Outer diameter at the top, measured over the ridge crests
pot_diameter = 100;
// Height of the outer pot (rim included)
pot_height = 100;
// Bottom diameter / top diameter (1 = straight sides, lower = more taper)
bottom_ratio = 0.8;

/* [Reservoir, walls and fit] */
// Water space between the outer floor and the underside of the inner pot
reservoir_depth = 25;
// Wall thickness (6 x 0.4 mm lines)
wall = 2.4;
// Floor thickness of both parts
base_thickness = 2.4;
// Gap between the inner pot and the outer pot (raise for a looser fit)
clearance = 0.4;
// Height of the collar that stands above the outer rim (also your finger grip)
collar_height = 1;
// Horizontal width of the conical seat at the top of the outer pot
seat = 1.4;
// Steepness of the seat, measured from vertical (smaller = steeper = easier to print; max 50)
seat_angle = 40;

/* [Spiral pattern] */
// Number of ridges around the pot
ridge_count = 12;
// Peak-to-valley depth of the ridges
ridge_depth = 2.4;
// Total twist from bottom to top in degrees (negative = other direction)
twist = 180;

/* [Drainage holes in the inner pot] */
hole_diameter = 5;
// Centre-to-centre distance between holes
hole_spacing = 12;
// Keep-out distance between holes and the wall
hole_margin = 3;

/* [Hidden] */
$fn = 1024;
bottom_chamfer = 1.2;   // height of the elephant-foot chamfer on the outer pot
bottom_chamfer_run = 0.8; // its horizontal width (less than the height = under 45 degrees)
inner_chamfer = 0.6;    // horizontal width of the 1 mm high elephant-foot chamfer on the inner pot

// ---------------------------------------------------------------------
//  Derived geometry
// ---------------------------------------------------------------------
Rt = pot_diameter / 2;                 // crest radius at the top
Rb = Rt * bottom_ratio;                // crest radius at the bottom
s_top = Rt / Rb;                       // scale applied by the twisted extrusion
Rv = Rt * (1 - ridge_depth / Rb);      // valley radius at the top
Cb = Rb - ridge_depth - wall;          // cavity radius at z = 0
Ct = Rv - wall;                        // cavity radius at z = pot_height
zb = base_thickness + reservoir_depth; // z of the inner pot's underside

m = (Ct - Cb) / pot_height;            // slope of the cavity radius (taper)
k = tan(seat_angle);                   // slope of the seat cone (radius per mm of height)
seat_dz = seat / k;                    // vertical height of the seat
z_seat = pot_height - seat_dz;         // where the seat starts

function lerp_z(a, b, z) = a + (b - a) * z / pot_height;
function cav(z) = lerp_z(Cb, Ct, z);   // outer pot: inner (cavity) radius
function rb(z)  = cav(z) - clearance;  // inner pot: outer radius
function env(z) = lerp_z(Rb, Rt, z);   // crest radius

r_seat_top = cav(z_seat) + seat;       // seat radius at the rim height where the inner pot's wall meets the seat cone
z1 = z_seat - clearance / (k - m);

// ---------------------------------------------------------------------
//  Sanity checks
// ---------------------------------------------------------------------
rim_flat = Rv - r_seat_top;
overhang = atan((ridge_depth / 2) * ridge_count * (abs(twist) * PI / 180 / pot_height) * s_top
                + (Rt - Rb) / pot_height);

assert(bottom_ratio > 0.4 && bottom_ratio <= 1, "bottom_ratio must be between 0.4 and 1");
assert(pot_height > reservoir_depth + 2 * base_thickness + 30,
       "pot_height is too small for this reservoir_depth");
assert(seat_angle > atan(m) + 5 && seat_angle <= 50,
       "seat_angle must be between about 10 and 50 degrees");
assert(rim_flat >= 0.8,
       "Rim too thin: increase wall, or reduce seat / ridge_depth");
assert(z1 > zb + 2,
       "Seat is too low for this reservoir_depth: reduce seat or increase pot_height");
assert(Ct > hole_diameter, "pot_diameter is too small for these settings");

echo(str("Outer pot, steepest outward overhang: about ", round(overhang), " deg (PETG prints well up to ~40-45)"));
echo(str("Inner pot, steepest overhang: ", seat_angle, " deg (seat cone); no flat underside"));
if (overhang > 45)
    echo("WARNING: ridges too steep. Reduce twist, ridge_depth or ridge_count.");
echo(str("Flat rim width: ", rim_flat, " mm"));
echo(str("Reservoir volume: about ", round(PI * pow(cav(zb / 2), 2) * reservoir_depth / 1000), " ml"));

// ---------------------------------------------------------------------
//  OUTER pot
// ---------------------------------------------------------------------
module wavy_profile() {
    n = ridge_count * 16;
    polygon([for (i = [0 : n - 1])
        let (a = 360 * i / n,
             r = Rb - ridge_depth / 2 + (ridge_depth / 2) * cos(ridge_count * a))
        [r * cos(a), r * sin(a)]]);
}

module spiral_body() {
    linear_extrude(height = pot_height, twist = twist, scale = s_top,
                   slices = max(ceil(pot_height / 2), ceil(abs(twist) / 2)),
                   convexity = 10)
        wavy_profile();
}

// Chamfers the bottom edge only; follows the crest line elsewhere.
module envelope() {
    rotate_extrude()
        polygon([[0, 0],
                 [env(bottom_chamfer) - bottom_chamfer_run + 0.05, 0],
                 [env(bottom_chamfer) + 0.05, bottom_chamfer],
                 [Rt + 0.05, pot_height],
                 [0, pot_height]]);
}

module outer_cavity() {
    rotate_extrude()
        polygon([[0, base_thickness],
                 [cav(base_thickness), base_thickness],
                 [cav(z_seat), z_seat],
                 [r_seat_top + k, pot_height + 1],      // conical seat, continued past the rim
                 [0, pot_height + 1]]);
}

module outer_part() {
    difference() {
        intersection() {
            spiral_body();
            envelope();
        }
        outer_cavity();
    }
}

// ---------------------------------------------------------------------
//  INNER pot
// ---------------------------------------------------------------------
// The outside widens along the seat cone from the wall (z1) up to the rim, then rises as a vertical collar. Nothing hangs out horizontally.
module inner_profile() {
    polygon([[0, zb],
             [rb(zb + 1) - inner_chamfer, zb],                  // bottom chamfer, under 45 degrees
             [rb(zb + 1), zb + 1],
             [rb(z1), z1],
             [r_seat_top, pot_height],                          // rests on the outer pot's seat
             [r_seat_top, pot_height + collar_height],
             [0, pot_height + collar_height]]);
}

module inner_cavity() {
    z0 = zb + base_thickness;
    rotate_extrude()
        polygon([[0, z0],
                 [rb(z0) - wall, z0],
                 [rb(pot_height) - wall, pot_height],
                 [rb(pot_height) - wall, pot_height + collar_height + 1],
                 [0, pot_height + collar_height + 1]]);
}

module drain_holes() {
    fr = rb(zb) - wall - hole_margin;
    rings = floor((fr - hole_diameter / 2) / hole_spacing);
    translate([0, 0, zb - 1])
        linear_extrude(height = base_thickness + 2)
            union() {
                circle(d = hole_diameter, $fn = 24);
                if (rings >= 1)
                    for (k = [1 : rings]) {
                        r = k * hole_spacing;
                        n = floor(2 * PI * r / hole_spacing);
                        for (i = [0 : n - 1])
                            rotate(i * 360 / n + (k % 2) * 180 / n)
                                translate([r, 0])
                                    circle(d = hole_diameter, $fn = 24);
                    }
            }
}

module inner_part() {
    difference() {
        rotate_extrude() inner_profile();
        inner_cavity();
        drain_holes();
    }
}

// ---------------------------------------------------------------------
//  Output
// ---------------------------------------------------------------------
module assembled() {
    color("sienna") outer_part();
    color("seagreen") inner_part();
}

if (part == "outer")
    outer_part();
else if (part == "inner")
    translate([0, 0, -zb]) inner_part();          // sits on the bed
else if (part == "assembly")
    assembled();
else if (part == "section")
    difference() {
        assembled();
        translate([-400, -400, -10]) cube([800, 400, pot_height + 100]);
    }
else {                                              // "print"
    outer_part();
    translate([pot_diameter + 10, 0, -zb]) inner_part();
}