// Ring Solar Charger — Vinyl Siding Adapter Plate
// BACKUP: flat upper rear + slow lower taper, no bead coping groove yet.
// Units: millimeters. Vanilla OpenSCAD only.

/* [Plate] */
plate_width = 93.1;
plate_height = 171.45;
min_wall_thickness = 3.0;
edge_round = 0;

/* [Siding Profile] */
siding_projection = 27.0;
face_inset_depth = 8.0;
flat_upper_ratio = 0.55;
course_pitch = 165.1;
profile_segments = 8;
profile_mode = "curved";
rear_clearance = 0.2;

/* [Mounting Holes] */
mount_hole_offset_top = 50.0;
mount_hole_offset_bottom = 44.7;
mount_hole_dia = 4.5;
mount_hole_x = 0;

/* [Export] */
part_mode = "full";
profile_strip_width = 20;

/* [Hidden] */
$fn = 64;
epsilon = 0.01;

function projection_z() = siding_projection - rear_clearance;

function face_inset_z() = projection_z() - face_inset_depth;

function face_y_flat_end() = plate_height * (1 - flat_upper_ratio);

function lower_curve_z(y) =
    let(
        y1 = face_y_flat_end(),
        t = y / max(y1, epsilon),
        ease = pow(sin(t * 90), 1.4),
        z_bottom = projection_z(),
        z_top = face_inset_z()
    )
    z_top + (z_bottom - z_top) * (1 - ease);

function stepped_rear_z(y) =
    y >= face_y_flat_end() ? face_inset_z() : projection_z();

function rear_z_at(y) =
    y >= face_y_flat_end() ? face_inset_z()
    : profile_mode == "stepped" ? stepped_rear_z(y)
    : lower_curve_z(y);

function rear_profile_points() =
    let(step = plate_height / max(profile_segments * 12, 24))
    [for (y = [0 : step : plate_height])
        [y, rear_z_at(y)]];

function max_rear_z() =
    let(pts = rear_profile_points())
    max([for (p = pts) p[1]]);

function front_z() = max_rear_z() + min_wall_thickness;

function rear_y_min() =
    min([for (p = rear_profile_points()) p[1]]);

function minkowski_active() =
    edge_round > 0 && min_wall_thickness >= 2 * edge_round + 1;

function hole_y_min() =
    rear_y_min() - (minkowski_active() ? edge_round : 0) - epsilon;

function hole_y_max() =
    front_z() + (minkowski_active() ? edge_round : 0) + epsilon;

function cross_section_polygon() =
    let(
        rear_pts = rear_profile_points(),
        fz = front_z()
    )
    [
        for (p = rear_pts) p,
        [plate_height, fz],
        [0, fz]
    ];

module cross_section_2d() {
    polygon(cross_section_polygon());
}

module adapter_body(width) {
    linear_extrude(width, center = true)
        cross_section_2d();
}

module mount_holes() {
    y_min = hole_y_min();
    y_max = hole_y_max();
    hole_depth = y_max - y_min;
    center_y = (y_min + y_max) / 2;
    for (y_pos = [plate_height - mount_hole_offset_top, mount_hole_offset_bottom]) {
        translate([y_pos, center_y, mount_hole_x])
            rotate([90, 0, 0])
                cylinder(h = hole_depth, d = mount_hole_dia, center = true);
    }
}

module rounded_body(width) {
    if (minkowski_active()) {
        minkowski() {
            adapter_body(max(width - 2 * edge_round, 1));
            sphere(r = edge_round);
        }
    } else {
        adapter_body(width);
    }
}

module adapter_plate() {
    width = part_mode == "profile_strip" ? profile_strip_width : plate_width;
    if (part_mode == "full") {
        difference() {
            rounded_body(width);
            mount_holes();
        }
    } else {
        rounded_body(width);
    }
}

adapter_plate();