first 3bb tutprial, uses lispbuilder-sdl, creates a window and a rainbow triangle!

3bb-1.lisp

@@ -0,0 +1,37 @@
+(defmacro restartable (&body body)
+  "Helper macro since we use continue restarts a lot 
+   (remember to hit C in slime or pick the restart so errors don't kill the app"
+  `(restart-case
+       (progn ,@body)
+     (continue () :report "Continue")))
+
+(defun draw ()
+  "draw a frame"
+  (gl:clear :color-buffer-bit)
+  ;;; draw a triangle
+  (gl:with-primitive :triangles
+    (gl:color 1 0 0)
+    (gl:vertex 0 0 0)
+    (gl:color 0 1 0)
+    (gl:vertex 0.5 1 0)
+    (gl:color 0 0 1)
+    (gl:vertex 1 0 0))
+  ;; finish the frame
+  (gl:flush)
+  (sdl:update-display))
+
+(defun main-loop () 
+  (sdl:with-init ()
+    (sdl:window 320 240 :flags sdl:sdl-opengl)
+    ;; cl-opengl needs platform specific support to be able to load GL
+    ;; extensions, so we need to tell it how to do so in lispbuilder-sdl
+    (setf cl-opengl-bindings:*gl-get-proc-address* #'sdl-cffi::sdl-gl-get-proc-address)
+    (sdl:with-events () 
+      (:quit-event () t)
+      (:idle ()
+	     ;; this lets slime keep working while the main loop is running
+             ;; in sbcl using the :fd-handler swank:*communication-style*
+             ;; (something similar might help in some other lisps, not sure which though)
+	     #+(and sbcl (not sb-thread)) (restartable
+                                           (sb-sys:serve-all-events 0))
+             (restartable (draw))))))