Using the shader for circle menu godot 4

circle_menu_shader.gdshader

shader_type canvas_item;

uniform float segment_width = 0.2; // Angular width of each segment (radians)
uniform float inner_radius = 0.1; // Inner radius of segments (UV space, 0.0–0.5)
uniform float outer_radius = 0.5; // Outer radius of segments (UV space, 0.0–0.5)
uniform float rotation_offset = 0.0; // Rotation offset in radians
uniform int segments = 8; // Number of segments (menu items)
uniform int selected_index = 0; // Selected segment (0–7)
uniform vec4 line_color = vec4(1.0, 1.0, 1.0, 1.0); // Non-selected segment color
uniform vec4 selected_color = vec4(1.0, 0.5, 0.5, 1.0); // Selected segment color
uniform float background_opacity = 0.3; // Background circle opacity

void fragment() {
    vec2 uv = UV - 0.5; // Center UV (0.5, 0.5 is center)
    float dist = length(uv); // Distance from center
    float angle = atan(uv.y, uv.x); // Pixel angle
    // Apply rotation offset
    angle = mod(angle + rotation_offset + 2.0 * 3.14159265, 2.0 * 3.14159265);
    float segment_angle = 2.0 * 3.14159265 / float(segments); // Angle per segment

    // Calculate segment index for the pixel
    int pixel_segment = int(angle / segment_angle) % segments;
    // Check if pixel is within a segment's angular width
    float angle_diff = mod(angle, segment_angle);
    float center_angle = segment_angle * 0.5;
    bool is_segment = abs(angle_diff - center_angle) < segment_width * 0.5 && dist >= inner_radius && dist <= outer_radius;

    // Check if pixel is in the selected segment
    bool is_selected = (pixel_segment == selected_index) && is_segment;

    // Draw background circle
    vec4 color = vec4(0.0); // Transparent default
    if (dist >= inner_radius && dist <= outer_radius) {
        color = vec4(0.2, 0.2, 0.2, background_opacity); // Background
    }

    // Draw segments
    if (is_segment) {
        color = is_selected ? selected_color : line_color;
    }

    COLOR = color;
}