I've come up with a gist that shows how it's done: https://gist.github.com/aknuds1/533f7b228aa46e9ee4c8.
Arve On Wed, Sep 17, 2014 at 12:18 AM, Chad Austin <c...@imvu.com> wrote: > At the moment, I don't have the time (or the hardware / configuration) to > get your code up and running, but if someone else could take a look, this > would be a great candidate for an example to put on the wiki. Having > JavaScript interact with C is quite common. > > On Tue, Sep 16, 2014 at 2:59 PM, Arve Knudsen <arve.knud...@gmail.com> > wrote: > >> Thanks very much for the info, Chad. Would it be possible for you to >> amend my gist to employ your technique?? >> >> Best, >> Arve >> >> On Tue, Sep 16, 2014 at 11:36 PM, Chad Austin <c...@imvu.com> wrote: >> >>> If you want to write the C code such that it writes to a float*, then >>> that data has to live inside the Emscripten heap. >>> >>> That is, JavaScript must reserve some space in the Emscripten heap (via >>> _malloc, for example), and pass the pointer to the C function. >>> >>> Then, JavaScript can read the floats out of the array by accessing >>> HEAPF32[(p>>2) + index] where p is the pointer returned by _malloc and >>> index is the index into the array. >>> >>> >>> On Tue, Sep 16, 2014 at 2:17 PM, Arve Knudsen <arve.knud...@gmail.com> >>> wrote: >>> >>>> Hi guys >>>> >>>> I need to pass an array of floating point numbers from a JavaScript >>>> library to a C callback, so that the latter can fill the array with data. >>>> I'm using Runtime.getFuncWrapper to be able to call the C callback from >>>> JavaScript. >>>> >>>> How do I pass an array to the C callback, so that it appears as a >>>> writeable array of floats to the latter? >>>> >>>> I've created a gist of an Emscripten-generated HTML page, to >>>> demonstrate the scenario: >>>> https://gist.github.com/aknuds1/fd6348ab32583dea8b4a. It shows what >>>> I've tried so far, the problem being that the data written to the array by >>>> the C function doesn't make it back to the calling JavaScript function. >>>> Compile the gist into an HTML page like so: >>>> >>>> emcc --js-library library.js -o tst.html tst.cpp. >>>> >>>> The JavaScript function is called 'initialize', while the C callback is >>>> called 'callback'. Let me know if anything is unclear. >>>> >>>> Thanks, >>>> Arve >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "emscripten-discuss" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to emscripten-discuss+unsubscr...@googlegroups.com. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> >>> >>> -- >>> Chad Austin >>> Technical Director, IMVU >>> http://engineering.imvu.com <http://www.imvu.com/members/Chad/> >>> http://chadaustin.me >>> >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "emscripten-discuss" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to emscripten-discuss+unsubscr...@googlegroups.com. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "emscripten-discuss" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to emscripten-discuss+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > Chad Austin > Technical Director, IMVU > http://engineering.imvu.com <http://www.imvu.com/members/Chad/> > http://chadaustin.me > > > -- > You received this message because you are subscribed to the Google Groups > "emscripten-discuss" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to emscripten-discuss+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to emscripten-discuss+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
