;; Example 5-6  Moving a light with modeling transformations

(use gl)
(use gl.glut)

(define *spin* 0)

(define (init)
  (gl-clear-color 0.0 0.0 0.0 0.0)
  (gl-shade-model GL_SMOOTH)
  (gl-enable GL_LIGHTING)
  (gl-enable GL_LIGHT0)
  (gl-enable GL_DEPTH_TEST)
  )

(define (disp)
  (gl-clear (logior GL_COLOR_BUFFER_BIT GL_DEPTH_BUFFER_BIT))
  (gl-push-matrix)
  (gl-translate 0.0 0.0 -5.0)

  (gl-push-matrix)
  (gl-rotate *spin* 1.0 0.0 0.0)
  (gl-light GL_LIGHT0 GL_POSITION '#f32(0.0 0.0 1.5 1.0))

  (gl-translate 0.0 0.0 1.5)
  (gl-disable GL_LIGHTING)
  (gl-color 0.0 1.0 1.0)
  (glut-wire-cube 0.1)
  (gl-enable GL_LIGHTING)
  (gl-pop-matrix)

  (glut-solid-torus 0.275 0.85 8 15)
  (gl-pop-matrix)
  (gl-flush)
  )

(define (reshape w h)
  (gl-viewport 0 0 w h)
  (gl-matrix-mode GL_PROJECTION)
  (gl-load-identity)
  (glu-perspective 40.0 (/ w h) 1.0 20.0)
  (gl-matrix-mode GL_MODELVIEW)
  (gl-load-identity)
  )

(define (mouse button state x y)
  (when (and (= button GLUT_LEFT_BUTTON) (= state GLUT_DOWN))
    (set! *spin* (modulo (+ *spin* 30) 360))
    (glut-post-redisplay)))

(define (keyboard key x y)
  (when (= key 27) (exit 0)))

(define (main args)
  (glut-init args)
  (glut-init-display-mode (logior GLUT_SINGLE GLUT_RGB GLUT_DEPTH))
  (glut-init-window-size 500 500)
  (glut-init-window-position 100 100)
  (glut-create-window *program-name*)
  (init)
  (glut-display-func disp)
  (glut-reshape-func reshape)
  (glut-mouse-func mouse)
  (glut-keyboard-func keyboard)
  (glut-main-loop)
  0)