lighttroupe/luz-next

module GL
    def self.SaveMatrix
        begin
            self.PushMatrix
            yield
        ensure
            self.PopMatrix
        end
    end

    def self.PushAll
        begin
            GL.PushAttrib(GL::ALL_ATTRIB_BITS)
            GL.PushMatrix
            yield
        ensure
            GL.PopMatrix
            GL.PopAttrib
        end
    end

    # Generates display list (using yield block)
    # call like   display_list = GL.RenderCached(display_list) { GL.calls... }
    def self.RenderCached(list)
        list ||= RenderToList { yield }        # Generate, if necessary
        return nil unless list                        # For nested calls to RenderToList
        GL.CallList(list)
        return list
    end

    def self.RenderToList
        if $rendering_to_list
            # OpenGL can't define lists recursively, so instead we include the
            # contents of the inner list in the outer one
            yield
            return nil
        else
            list = GL.GenLists(1)
            GL.NewList(list, GL::COMPILE)
                $rendering_to_list = true
                yield
                $rendering_to_list = false
            GL.EndList
            return list
        end
    end

    def self.DestroyList(list)
        GL.DeleteLists(list, 1)
    end

    def self.GetColorArray
        GL.GetDoublev(GL::CURRENT_COLOR)
    end

    def self.GenTexture
        GenTextures(1).first
    end
end