shader_type spatial;
render_mode unshaded;

uniform vec4 light_color : source_color = vec4(1.0, 1.0, 1.0, 1.0);
uniform sampler2D albedo_texture;
uniform float outline_width = 0.05; // Thickness of outline
uniform vec4 outline_color : source_color = vec4(0.0, 0.0, 0.0, 1.0);

void vertex() {
    // Expanding vertices along normals for outlines (inverted hull technique)
    if (OUTLINE_PASS) {
        VERTEX += NORMAL * outline_width;
    }
}

void fragment() {
    vec3 light_dir = normalize(vec3(0.5, 1.0, -0.5)); // Fake directional light
    vec3 norm = normalize(NORMAL);
    float intensity = dot(norm, light_dir);

    // Cel shading (quantized lighting levels)
    float shade = smoothstep(0.1, 0.3, intensity) * 0.5 +
                  smoothstep(0.3, 0.6, intensity) * 0.3 +
                  smoothstep(0.6, 1.0, intensity) * 0.2;

    // Sample texture and apply shading
    vec4 tex_color = texture(albedo_texture, UV);
    vec3 final_color = tex_color.rgb * shade * light_color.rgb;

    // Outline pass
    if (OUTLINE_PASS) {
        final_color = outline_color.rgb;
    }

    ALBEDO = final_color;
}