lighttroupe/luz-next

#
# Drawing of the X,Y,Z axes
#
class CartesianScaffolding
    MAJOR_GRIDLINE_COLOR = Color.new([1.0, 1.0, 1.0, 0.3])

    include Drawing

    def render
        draw_scaffolding
    end

private

    def draw_scaffolding
        # Paint the scaffolding, writing and testing depths
        GL.Enable(GL::DEPTH_TEST)
        GL.DepthMask(true)                # write depths
        GL.DepthFunc(GL::LEQUAL)    # nearer or newer

        GL.LineWidth(1.0)
        GL.PointSize(3.0)
        draw_origin_cross

        with_color(MAJOR_GRIDLINE_COLOR) {
            GL.LineWidth(1.0)
            with_roll(0.25, x=1.0, y=0.0, z=0.0) {
                with_scale(10) {
                    draw_grid(10)
                }
            }
        }
        GL.Disable(GL::DEPTH_TEST)
    end

    def draw_origin_cross(distance=5.0)
        alpha = 0.9
#        @origin_cross_list ||= {}
#        @origin_cross_list[distance] ||= GL.RenderToList {
            with_color([1.0, 0.0, 0.0, alpha]) { draw_origin_line_x(distance) }
            with_color([0.0, 1.0, 0.0, alpha]) { with_roll(0.25, 0.0, 0.0, 1.0) { draw_origin_line_x(distance) } }
            with_color([0.0, 0.0, 1.0, alpha]) { with_roll(0.25, 0.0, 1.0, 0.0) { draw_origin_line_x(distance) } }
#        }
#        GL.CallList(@origin_cross_list[distance])
    end

    def draw_origin_line_x(distance)
        GL.Begin(GL::LINES)
            GL.Vertex(distance, 0.0, 0.0) ; GL.Vertex(-distance, 0.0, 0.0)
        GL.End

        GL.Begin(GL::POINTS)
            (-distance).step(distance, 0.5) { |d| GL.Vertex(d, 0.0, 0.0) }
        GL.End
    end

    def draw_grid(grid_lines)
        GL.Begin(GL::LINES)
            (-0.5).step(0.5, 1.0 / grid_lines) { |x| GL.Vertex(x, 0.5) ; GL.Vertex(x, -0.5) }
            (-0.5).step(0.5, 1.0 / grid_lines) { |y| GL.Vertex(0.5, y) ; GL.Vertex(-0.5, y) }
        GL.End
    end
end