//
// wedge.scad
// 2026-03-06 ChatGPT
// $Header$
//
// Render preview:
//   openscad color_wedge_chart.scad
//
// Export STL from command line:
//   openscad -o color_wedge_chart_20260306_0000.stl color_wedge_chart.scad
//

$fn = 120;

// ------------------------------------------------------------
// Global parameters
// ------------------------------------------------------------

slice_count      = 10;
slice_angle      = 360 / slice_count;   // 36 degrees
explode_gap      = 12;

inner_r          = 18;
outer_r          = 78;
thickness        = 5;

// Crown shaping
cap_z0           = thickness;
cap_z1           = thickness + 3;
cap_z2           = thickness + 7;
cap_z3           = thickness + 5;

// Radial positions controlling the top profile
cap_r0           = inner_r + 6;
cap_r1           = inner_r + 18;
cap_r2           = outer_r - 18;
cap_r3           = outer_r - 4;

// Text
label_size       = 8;
label_height     = 1.2;
label_font       = "Liberation Sans:style=Bold";

// Small epsilon for clean CSG
eps              = 0.05;


// ------------------------------------------------------------
// 2D annular wedge sector
// Angle starts at 0 and runs to ang degrees
// ------------------------------------------------------------

module wedge_2d(r1, r2, ang, step=2) {
    pts = concat(
        [ for (a = [0:step:ang]) [r2*cos(a), r2*sin(a)] ],
        [ for (a = [ang:-step:0]) [r1*cos(a), r1*sin(a)] ]
    );
    polygon(points = pts);
}


// ------------------------------------------------------------
// Thin radial band of the wedge
// Used for hull() operations to create faceted crown surfaces
// ------------------------------------------------------------

module wedge_band(r1, r2, ang, z, h=eps) {
    translate([0,0,z])
        linear_extrude(height = h)
            wedge_2d(r1, r2, ang);
}


// ------------------------------------------------------------
// Base body of the wedge
// ------------------------------------------------------------

module wedge_base() {
    linear_extrude(height = thickness)
        wedge_2d(inner_r, outer_r, slice_angle);
}


// ------------------------------------------------------------
// Simple faceted cap
// This is the starter version of the crown.
// It creates a raised table-like region and sloped sides.
// ------------------------------------------------------------

module wedge_cap_simple() {
    union() {

        hull() {
            wedge_band(cap_r0, cap_r1, slice_angle, cap_z0);
            wedge_band(cap_r1, cap_r2, slice_angle, cap_z1);
        }

        hull() {
            wedge_band(cap_r1, cap_r2, slice_angle, cap_z1);
            wedge_band(cap_r2, cap_r3, slice_angle, cap_z2);
        }

        hull() {
            wedge_band(cap_r2, cap_r3, slice_angle, cap_z2);
            wedge_band(cap_r3, outer_r, slice_angle, cap_z3);
        }
    }
}


// ------------------------------------------------------------
// Raised number on underside
// Number is centered approximately on the wedge centerline.
// ------------------------------------------------------------

module wedge_label(idx) {
    mid_r = (inner_r + outer_r) / 2;
    mid_a = slice_angle / 2;

    x = mid_r * cos(mid_a);
    y = mid_r * sin(mid_a);

    translate([x, y, 0])
        mirror([0,0,1])
        translate([0,0,label_height])
        rotate([180,0,mid_a - 90])
        linear_extrude(height = label_height)
            text(str(idx), size = label_size, halign = "center", valign = "center", font = label_font);
}


// ------------------------------------------------------------
// Single wedge object
// ------------------------------------------------------------

module wedge_unit(idx=0) {
    union() {
        wedge_base();
        wedge_cap_simple();
        wedge_label(idx);
    }
}


// ------------------------------------------------------------
// Full 10-part exploded wheel
// Each wedge is translated outward along its own centerline.
// ------------------------------------------------------------

module wheel_10() {
    for (i = [0:slice_count-1]) {
        a = i * slice_angle;
        mid_a = a + slice_angle/2;

        dx = explode_gap * cos(mid_a);
        dy = explode_gap * sin(mid_a);

        translate([dx, dy, 0])
            rotate([0,0,a])
                wedge_unit(i);
    }
}


// ------------------------------------------------------------
// Top-level render
// ------------------------------------------------------------

wheel_10();