Traffic cone with shadow in OpenSCAD

cone.scad

// Animation settings
$vpr = [45,0,-90];
$vpt = [0,0,05];
$vpd = 250;

// Colors
shade  = [0.5,0.5,0.45,1];
orange = [1.0,0.5,0.0,1];
black  = [0.2,0.2,0.2,1];
white  = [0.9,0.9,0.9,1];

// Cone dimensions
s = 30;
h = s/2;
d = s*2;
w = h*4.5;

// Shadow parameters
shadow_angle = 45;  // Angle of the shadow (45° = southeast)

zoom = 1.5;
shad = -1;  // -1 = shadow+cone, 0 = cone, 1 = shadow

// Shadow projection matrix
function shadow_matrix(angle) = [
    [1, 0, -cos(angle), 0],
    [0, 1, -sin(angle), 0],
    [0, 0, 0, 0],
    [0, 0, 0, 1]
];

// Helper module for rounded rectangles
module rounded_rect(size, radius) {
    r = (radius > size[0]/2 || radius > size[1]/2) ? 
        min(size[0]/2, size[1]/2) : radius;
    square_size = [size[0] - 2*r, size[1] - 2*r];
    minkowski() {
        square(square_size, center=true);
        circle(r);
    }
}

// Cone module
module cone() {
    difference() {
        difference() {
            union() {
                // Raised stripe
                intersection() {
                    color(white)
                    translate([0,0,10])
                    cylinder(20,8.025,2, center = true, $fn=64);
            
                    color(white)
                    translate([0,0,11])
                    cube([20,20,7], center = true);
                }
                
                // Main cone body
                color(orange)
                translate([0,0,10])
                cylinder(20,8,2, center = true, $fn=64);
                
                // Base
                color(black)
                translate([0,0,-0.01])
                linear_extrude(height = 3, scale = 0.9) {
                    rounded_rect([19, 19], 5, $fn=32);
                }
            }
            
            // Tip hole
            color(orange)
            translate([0,0,13])
            cylinder(8, 3, 1, center = false, $fn=32);
        }
        
        // Inner hole
        color(orange)
        translate([0,0,8])
        cylinder(18,7,2, center = true, $fn=64);
    }
}

// Shadow calculation that maintains southeast direction
// -- approx
// module shadow() {
//     translate([0, 0, 0.01])
//     color(shade)
//     multmatrix(shadow_matrix(shadow_angle))
//     // hull()
//     modified_cone();
// }
// -- accurate
module shadow() {
    translate([0, 0, 0.01])
    color(shade)
    render()  // Force rendering to help prevent z-fighting
    scale([1, 1, 0.001])  // Flatten instead of using hull()
    multmatrix(shadow_matrix(shadow_angle))
    modified_cone();
}

module modified_cone() {
    scale(zoom)
    rotate([0,0,180-$t*360])    // ANIMATION
    translate([0,0,9.1])    // cone knocked over
    rotate([0,111,0])       //
    cone();
}

module final() {
    // Render the cone
    if ( shad == 0 || shad == -1 ) {
        modified_cone();  // Rotated cone
    }
    // Render shadow
    if (shad == 1 || shad == -1) {
        shadow();       // Southeast-projected shadow
    }
}
final();