Dear Racket community, I need your help. Once upon a time, I was looking for a Racket physics engine. I looked around and found a few different bindings from Racket to the Chipmunk physics engine. However, none of these repositories appeared to be maintained. None of them used the latest version of Chipmunk. And they didn't work (for me) out of the box.
So... in my hubris, I decided to learn the Racket FFI and make my own Racket/Chipmunk bindings. Hence... this repo was born: https://github.com/thoughtstem/racket-chipmunk Still confident, I integrated my racket-chipmunk library into my Racket-based game-engine (https://github.com/thoughtstem/game-engine). I THOUGHT all was well. It worked great. For a time, I was happy. But then... Three bad things happened: 1) First, I tried (and failed) to integrate the Rsound library into game-engine. I thought (at the time) this was a problem in Rsound -- since the stack trace pointed me to the RSound code. Here's the issue I opened: https://github.com/jbclements/RSound/issues/38 2) Then, later, when I saw the same error pop up with the Lux library, I started to think that maybe something in game-engine was at fault. I did some digging and discovered racket-chipmunk to be the culprit. Here's the issue where I came to that discovery: https://github.com/jeapostrophe/lux/issues/9 3) Now, a few days ago, I began to see a similar issue when I tried to integrate Mode Lambda into game-engine. Once again, racket-chipmunk seems to be interfering with another library. There's no explicit error message this time. But the rendering is broken. Here's the issue I opened about that: https://github.com/jeapostrophe/mode-lambda/issues/19 Feel free to follow those links to the issues for further information if you wish, but to save you some time, I'll try to sketch out the high level idea here. Basically, in my racket-chipmunk library (in this file https://github.com/thoughtstem/racket-chipmunk/blob/master/lang/chipmunk-ffi.rkt), I have these two lines: (require ffi/unsafe) (define chipmunk (ffi-lib "./binaries/libchipmunk")) These two lines seem to subtly "poison" the Racket process (until I restart). What I mean is that if I run those lines in ANY DrRacket tab, I immediately start to get subtle errors with programs launched from ANY other tabs -- whether or not those programs are even related to each other. 1) With RSound and Lux the subtle error is that when those libraries (require math/flonum) it triggers a puzzling error inside of math/flonum. 2) With Mode Lambda, the subtle error is that all Mode Lambda programs, including the Mode Lambda examples, render just solid black. The idea that something that gets run in one tab will poison things I run in other tabs makes this bug uncharted territory (for me). I've personally never seen that in DrRacket. So I don't even have a clear hypothesis about what might be going wrong under the hood. I also don't have any skills for debugging stuff that is going wrong under the hood in Racket. To make matters MUCH worse, I only see the above phenomenon on certain Linux machines. (But I have a few hundred of those machines -- so it's still very important for me to fix this issue). Basically, I need the community's help here. Has anyone seen a bug with a similar "feel"? Has anyone seen this exact phenomenon? Can someone tell me if I'm doing something obviously wrong with my FFI code? Can someone tell me if there is something special I needed to have done when compiling the Chipmunk C libraries? Can anyone give me a way to seek out more information to narrow down the issue? I would genuinely appreciate any help. Thanks, Stephen -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
