OpenGL Hello World

hellogl.rkt

#lang racket/gui
(require sgl)
(require sgl/gl-vectors)

(define (render canvas dc)
        (send canvas with-gl-context
            (lambda ()
                (gl-matrix-mode 'projection)
                (gl-load-identity)
                (gl-ortho -10 10 -10 10 -1 1)

                (gl-clear-color 0.0 0.0 0.0 0.0)
                (gl-clear 'color-buffer-bit 'depth-buffer-bit)

                (gl-begin 'triangles)
                (gl-vertex 0 0 0)
                (gl-vertex 0 5 0)
                (gl-vertex 5 0 0)
                (gl-end)

                (send canvas swap-gl-buffers)
                (gl-flush)
            )))


(define frame (new frame%
                   [label "Example"]
                   [width 640]
                   [height 640]))
(new canvas% [parent frame]
             [style '(gl)]
             [paint-callback render])
(send frame show #t)