(bind-func nvg_draw_loop
(lambda (time:i64 delta_t:double)
(nvg_clear)
;;(draw_a_line)
;;(draw_a_circle)
;;(draw_circle_loop)
(glfwPollEvents)
(glfwSwapBuffers window)
(let ((next_time (+ time (convert (* 44100. delta_t)))))
(callback next_time nvg_draw_loop next_time delta_t))))