[racket-dev] Pre-Release Checklist for v6.0, corrected url

From: Neil Toronto (neil.toronto at gmail.com)
Date: Mon Dec 30 01:52:41 EST 2013

I don't think there's anything I can look into. I can't duplicate the 
problem on my system, and Plot doesn't do anything platform-specific, so 
the bug is almost certainly in `pict', `racket/draw' or Cairo. Matthew?

Sorry I wasn't clear on this earlier.

(It could be that it's *possible* duplicate it on my system, and that it 
only shows up on the build machine because the default font is a 
different size, which gives the plot areas slightly different sizes, 
which gives the projected triangles slightly different vertices. I could 
look into that, but it seems unlikely. I use Plot a *lot* and have never 
seen this before.)

If I were debugging it, I'd try to find the simplest plot that's missing 
a polygon. Here are the bad plots from the docs, rendered the way the 
docs do it (plot to a pict, then convert to a bitmap), with the number 
of samples easy to tweak:

#lang racket

(require pict plot/pict)

(plot3d-samples 41)  ; default is 41

(parameterize ([plot-z-ticks  (currency-ticks)])
    (plot3d-pict (contour-intervals3d (λ (x y) (- (sqr x) (sqr y)))
                                      -1 1 -1 1
                                      #:label "z")
                 #:legend-anchor 'center)))

  (plot3d-pict (polar3d (λ (θ ρ) 1)
                        #:color 2
                        #:line-style 'transparent)
               #:altitude 25))

I'd also try passing #:out-file "out.pdf" to `plot3d-pict' to see if the 
PDF back-end is afflicted.

I don't know how worried to be about missing polygons. It could be 
anything from bad array management in Cairo (which could be serious) to 
a mostly harmless problem in the implementation of region culling or 
winding rules.

Neil ⊥

On 12/29/2013 09:39 PM, Robby Findler wrote:
> Neil: have you had time to look into this? If not, then I think we
> should just leave it for the next release. Please let us know what
> you're thinking about this one.
> Robby
> On Sat, Dec 21, 2013 at 4:13 PM, Neil Toronto <neil.toronto at gmail.com
> <mailto:neil.toronto at gmail.com>> wrote:
>     Some plots in the documentation are missing a polygon. I think it's
>     platform-specific, because I can't reproduce the problem.
>     Examples:
>     First example plot in "1.5 Renderer and Plot Bounds" (look for a
>     light green rectangle)
>     file:///usr/racket-
>     Last example plot in `plot-z-far-ticks' docs (look for a white hole
>     under the "z" in the legend)
>     http://plt.eecs.northwestern.__edu/snapshots/current/doc/__plot/ticks_and_transforms.__html?q=plot-z-far-ticks#%__28def._%28%28lib._plot%2Fmain.__.rkt%29._plot-z-far-ticks%29%__29
>     <http://plt.eecs.northwestern.edu/snapshots/current/doc/plot/ticks_and_transforms.html?q=plot-z-far-ticks#%28def._%28%28lib._plot%2Fmain..rkt%29._plot-z-far-ticks%29%29>
>     Here's a program that renders one of the bad plots like Scribble
>     does (I think):
>     #lang racket
>     (require pict plot/pict)
>     (pict->bitmap
>       (plot3d-pict (polar3d (λ (θ ρ) 1) #:color 2 #:line-style 'transparent)
>                    #:altitude 25))
>     Neil ⊥
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