lighttroupe/luz-next

class ActorEffectStipple < ActorEffect
    title                "Stipple"
    description "Represent image using a grid of dots."

    categories :color

    setting 'segments', :integer, :range => 1..5000, :default => 100..10000, :shader => true
    setting 'size', :float, :range => 0.0..1.0, :default => 1.0..1.0, :shader => true

    CODE = "
        float floor_x = floor(texture_st.x * float(segments));
        float floor_y = floor(texture_st.y * float(segments));

        float square_side_length = (1.0 / float(segments));
        float center_x = (floor_x * square_side_length) + (square_side_length * 0.5);
        float center_y = (floor_y * square_side_length) + (square_side_length * 0.5);

        // from center
        float delta_x = (texture_st.x - center_x);
        float delta_y = (texture_st.y - center_y);

        float radius_squared = (square_side_length * 0.707 * size);        // sqrt(0.5^2 + 0.5^2) = 0.707 (stipple circles touches square corner at size == 1.0)
        radius_squared = radius_squared * radius_squared;

        if(((delta_x*delta_x) + (delta_y*delta_y)) < radius_squared) {
            texture_st.x = center_x;
            texture_st.y = center_y;
        } else {
            output_rgba = vec4(0.0,0.0,0.0,0.0);
        }
    "

    def render
        with_fragment_shader_snippet(CODE, self) {
            yield
        }
    end
end