class MY_SURFACE

	inherit

		EM_SURFACE

		GL_FUNCTIONS_EXTERNAL
		export {NONE} all end

		GLU_FUNCTIONS_EXTERNAL
		export {NONE} all end


feature

	gl_enter_2d is
			-- Enter 2d mode using opengl.
		do
			if
				not gl_2d_mode
			then

				gl_push_attrib_external ( em_gl_enable_bit | em_gl_color_buffer_bit )
				gl_disable_external ( em_gl_depth_test )
				gl_disable_external ( em_gl_cull_face )
				gl_enable_external ( em_gl_texture_2d )
				gl_clear_color_external ( 0, 0, 0, 1 )

				  -- This allows alpha blending of 2D textures with the scene
					gl_enable_external (em_gl_blend)
					gl_blend_func_external (em_gl_src_alpha, em_gl_one_minus_src_alpha)

				gl_viewport_external ( 0, 0, width, height )

				-- Set perspective
				gl_matrix_mode_external ( em_gl_projection )
				gl_push_matrix_external
				gl_load_identity_external

				gl_ortho_external ( 0, width, height, 0, 0, 1 )

				gl_matrix_mode_external ( em_gl_modelview )
				gl_push_matrix_external
				gl_load_identity_external

				gl_tex_envf_external (em_gl_texture_env, em_gl_texture_env_mode, em_gl_replace)

				gl_2d_mode := true
			end
		ensure
			in_mode: gl_2d_mode
		end

	gl_leave_2d is
			-- Leave 2d mode using opengl
		do
			if
				gl_2d_mode
			then
				gl_matrix_mode_external ( em_gl_projection )
				gl_pop_matrix_external

				gl_matrix_mode_external ( em_gl_modelview )
				gl_pop_matrix_external

				gl_pop_attrib_external
				gl_2d_mode := false
			end
		ensure
			not_in_mode: not gl_2d_mode
		end


feature -- access

	gl_2d_mode: BOOLEAN





end