lighttroupe/luz

require 'gl_frame_buffer_object'

module DrawingFrameBufferObjects
    DEFAULT_FRAMEBUFFER_SIZE = :large
    FRAMEBUFFER_SIZES = {:large => {:width => 1024, :height => 768}, :medium => {:width => 512, :height => 384}, :small => {:width => 256, :height => 192}}

    def get_offscreen_buffer(size = DEFAULT_FRAMEBUFFER_SIZE)
        @fbo_to_size ||= {}            # so we know which stack to return it to
        @fbo_hash ||= {}                # hash[size] => [fbo, fbo, ...]
        @fbo_hash[size] ||= []

        if @fbo_hash[size].empty?
            fbo = GLFrameBufferObject.new(FRAMEBUFFER_SIZES[size])
            @fbo_to_size[fbo] = size        # record size of new framebuffer
            fbo
        else
            @fbo_hash[size].pop
        end
    end

    def return_offscreen_buffer(fbo)
        @fbo_hash[@fbo_to_size[fbo]] << fbo
    end

    def with_offscreen_buffer(size = DEFAULT_FRAMEBUFFER_SIZE)
        fbo = get_offscreen_buffer(size)
        yield fbo
        return_offscreen_buffer(fbo)
    end
end