`pict3d->bitmap` errors on OSX

[Spencer Florence]

#lang racket
(require pict3d)
(pict3d->bitmap (sphere origin 1/2))

Errors with:

OpenGL error in procedure glClear: Error code 1286.
  context...:
   /Applications/Racket/racket/share/pkgs/pict3d/typed/opengl/untyped.rkt:106:11: self-mutating-fun
   ...private/memo.rkt:101:34
   /Applications/Racket/racket/share/pkgs/pict3d/pict3d/private/memo.rkt:63:2
   /Applications/Racket/racket/share/pkgs/pict3d/pict3d/private/engine/draw/draw-passes.rkt:429:0: draw-draw-passes*
   ...e/gl/context.rkt:20:24
   /Applications/Racket/racket/collects/racket/contract/private/arrow-higher-order.rkt:346:33
   /Applications/Racket/racket/collects/racket/contract/private/arrow-higher-order.rkt:342:33
   /Applications/Racket/racket/share/pkgs/pict3d/pict3d/private/gui/untyped-pict3d-bitmap.rkt:29:0: pict3d->bitmap7
   ...ow-val-first.rkt:306:25

I'm on macOS 10.12.3

Some quick googling shows that error 1286 happens when the framebuffer is not ready to be read from/written too.

---

It looks like the error is coming from here: https://github.com/jeapostrophe/pict3d/blob/master/pict3d/private/engine/draw/draw-passes.rkt#L393

It seems like the call to glClear and glClearColor should be in a with-gl-framebuffer. However if I wrap those two in a (with-gl-framebuffer fbo ...), rebuild, and rerun, i get the same error here:

https://github.com/jeapostrophe/pict3d/blob/master/pict3d/private/engine/draw/draw-passes.rkt#L821

And I'm not sure how to go about fixing that one.

[Jay McCarthy]

I pushed something to fix this, but in the process I learned about how it was implemented. I'm skeptical the bitmaps ever worked. Right now, your test ends up with a black bitmap.

[Spencer Florence]

further developements:

This error has been happening irregulary when using the pict3d-snips and happens when set-pict3d is called on a pict3d-canvas%. But it does not happen when constructing the canvas (although the canvas does not render the pict properly).

I tried your fix on this program:

#lang racket
(require pict3d)

(pict3d->bitmap
 (combine (sphere origin 1/2)
          (light (pos 0 1 1) (emitted "azure" 2))))

And I get a black pict, but with the correct reflected glow coming off the sphere. So at least the lighting pass is working...?

[Spencer Florence]

Also, thanks for looking into this so fast!

[Jay McCarthy]

I believe this is fixed. I used this test to compare bitmaps vs canvas:

#lang racket/base
(require pict3d
         pict3d/universe
         racket/gui
         racket/class)

(module+ main
  (define p
    (combine (sphere origin 1/2)
             (light (pos 0 1 1) (emitted "azure" 2))))
  (define bm
    (pict3d->bitmap p))
  
  (thread
   (λ ()
     (define f (new frame% [label "Bitmap Test"]))
     (new canvas% [parent f]
          [min-width (send bm get-width)]
          [min-height (send bm get-height)]
          [paint-callback
           (λ (c dc)
             (send dc draw-bitmap
                   bm
                   0 0))])
     (send f show #t)))

  (define (on-draw s n t) p)
  (big-bang3d 0 #:on-draw on-draw))