Hi Scott, yes please do add me to the repo I’d love to take a look and pitch in as time allows.
On Mon, 19 Oct 2020 at 13:43, Scott Wilson <[email protected]> wrote: > Hey Anders, > > Cxx has so far been pretty okay. It's pretty manual (hopefully autocxx > makes it better, but as far as I know, it's still nowhere ready for using > it on OpenImageIO). Right now the process looks something like this: > > 1. Create a header/cpp file that contains all of your class methods as > functions. > 2. Create an unsafe Rust interferface that's a 1 to 1 copy of the C++ side. > 3. Create a safe Rust interface. > > For me, the really nice thing is I don't need to worry about the C++ -> C > -> Rust steps. It drops the C step, but I still need to write that C++ > "ugly" interface. > > Also, if you want to join in on the fun, our repo is currently private > while we get things to a working state. But, I can add you to the repo. > Otherwise, I'm up for a discussion on how to take both designs and come up > with the best one. > > On Sun, Oct 18, 2020 at 4:51 PM Anders Langlands < > [email protected]> wrote: > >> Wrapping C in Rust is a two-stage process: first writing an "unsafe" FFI >> binding to the C API, which is usually almost completely automated with a >> crate called bindgen, then writing a "safe" crate that provides a Rust-y >> API using the unsafe FFI bindings. Wrapping C++ means writing a C API >> first, then binding that to Rust, which is what my crate does. >> >> I've been meaning to return to this (and OSL, OpenSubdiv and others) at >> some point and try to make a project-specific C-binding generator using >> libclang, as manually maintaining the C stubs is laborious and error-prone. >> >> Scott, I'd be curious to know how you're getting on with cxx, I've been >> meaning to look into that. I'd be happy to collaborate on something we >> could integrate into the main project as Larry suggests. >> >> On Mon, 19 Oct 2020 at 12:30, Larry Gritz <[email protected]> wrote: >> >>> Feel free to have the discussion on-list, I'm sure it would be of >>> interest to many. >>> >>> If there was consensus on what the Rust APIs should look like, I would >>> welcome adding a set of Rust bindings to the main OIIO distribution. >>> Assuming that makes sense, I was thinking it would be much like we now have >>> with the Python bindings. The advantage to making Rust bindings part of the >>> main build would be that it could be built and tested as part of our CI, >>> versioned along with the rest of OIIO, and essentially never allowed to >>> break. Also, just like we would never accept a PR that added C++ >>> functionality without making sure the Python bindings kept up, we could >>> ensure that nothing is left out of the Rust bindings. While I can >>> appreciate the cleanliness and independence of it being a separate project, >>> I can't help but think that it will be a neverending nightmare to try to >>> keep the bindings in sync with the main project. >>> >>> I don't know how automated it is to make Rust bindings for C (I know >>> it's a PITA for C++), but if making Rust bindings is substantially easier >>> if you had minimal plain C wrappers for the major C++ classes, I'm sure >>> there would be a lot of happy consumers of that even outside the Rust >>> interest group. >>> >>> I haven't had time to try Rust myself for any programming project, >>> though I've followed it from afar and like the idea of helping that >>> community. TBH, the main thing that keeps me from spending any time on Rust >>> is just that I can't contemplate the hassle of trying to program without my >>> favourite libraries, and having OIIO (and its many utilities that I reuse >>> in basically everything I write) available in Rust will substantially lower >>> the bar for me to dabble in it more. >>> >>> -- lg >>> >>> >>> On Oct 18, 2020, at 4:12 PM, Scott Wilson <[email protected]> wrote: >>> >>> Hey Anders, >>> >>> We were inspired by what you did, and also decided to see if we can take >>> this in a slightly different direction/ use cxx. If you're interested in >>> discussing the wrapper more we can take it off the list. >>> >>> On Sun, Oct 18, 2020 at 3:35 PM Anders Langlands < >>> [email protected]> wrote: >>> >>>> I also have a rust binding here if you're interested: >>>> https://github.com/anderslanglands/oiio-rs >>>> >>>> On Sun, 18 Oct 2020 at 04:43, Scott Wilson <[email protected]> >>>> wrote: >>>> >>>>> Awesome, thank you very much! I'll try this out and see how badly I >>>>> break things. >>>>> >>>>> On Sat., Oct. 17, 2020, 1:02 a.m. Larry Gritz, <[email protected]> >>>>> wrote: >>>>> >>>>>> If you know the true legal extent of the memory allocation in which >>>>>> that data pointer is located (in this case, the beginning and ending of >>>>>> the >>>>>> vector, if you are passing a pointer to one of the elements of that >>>>>> vector), then I think you could certainly consider it an error if any of >>>>>> these addresses lay outside that buffer: >>>>>> >>>>>> data + xstride*width - 1 >>>>>> data + ystride*height - 1 >>>>>> data + ystride*(height - 1) + xstride*width - 1 >>>>>> data + zstride*depth >>>>>> data + zstride*(depth - 1) + ystride*height - 1 >>>>>> data + zstride*(depth - 1) + ystride*(height - 1) + xstride*width >>>>>> - 1 >>>>>> >>>>>> There may be a more succinct way to put that, but I think it covers >>>>>> all the cases of + and - strides. >>>>>> >>>>>> >>>>>> On Oct 17, 2020, at 12:42 AM, Scott Wilson <[email protected]> >>>>>> wrote: >>>>>> >>>>>> Thanks! I guess to come from this at a different angle, let's say I'm >>>>>> doing something like this: >>>>>> >>>>>> std::vector<uint8_t> pixels(10*10*3*1); >>>>>> ImageInput.read_image(TypeDesc::UINT8, @pixels[0]) >>>>>> >>>>>> Would there be a case where I could pick a stride value that would >>>>>> fall outside the pixels vector? >>>>>> >>>>>> PS: Thanks! I'm working on this with a friend, and hope to have >>>>>> something released in the near future. >>>>>> >>>>>> On Fri., Oct. 16, 2020, 11:47 p.m. Larry Gritz, <[email protected]> >>>>>> wrote: >>>>>> >>>>>>> Oops, my math was wrong (in an unimportant detail): If you are >>>>>>> making a mosaic of 16x5 of these 10x10 images, it is 80 small images you >>>>>>> are assembling in total, not 40. >>>>>>> >>>>>>> >>>>>>> On Oct 16, 2020, at 11:43 PM, Larry Gritz <[email protected]> wrote: >>>>>>> >>>>>>> The strides don't describe the size of the image, they are the >>>>>>> spacing in memory of where you want the values to be placed upon being >>>>>>> read >>>>>>> (or taken from in order to write). There is no invalid set of strides, >>>>>>> because the caller might want them to end up anywhere in memory. >>>>>>> >>>>>>> Or am I misunderstanding? >>>>>>> >>>>>>> For a fully "contiguous" memory buffer where you intend for every >>>>>>> plane, scanline, pixel, and channel immediately follows the previous >>>>>>> one, >>>>>>> then in our example the strides would be xstride=3, ystride=30, >>>>>>> zstride=300. (Though for a 2D image, the zstride is not used.) >>>>>>> >>>>>>> Here's an example of where you might have a stride range that is >>>>>>> wildly outside this: Let's say that you have 40 of these 10 x 10 x 3 x >>>>>>> uint8 image files and you are trying to read them in and assemble them >>>>>>> into >>>>>>> a single RGBA mosaic image of 16x5 x 4 x uint8 (the additional channel >>>>>>> is >>>>>>> alpha, which you will separately fill in as 1.0 [or 255 uint8] because >>>>>>> it's >>>>>>> not in your RGB files). Here's a cartoon to illustrate this: >>>>>>> >>>>>>> +-----------------------------------------+ >>>>>>> | | | | | | | | | | | | | | | | | | | | | | >>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| >>>>>>> | | | | | | | | | | | | | | | | | | | | | | >>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| >>>>>>> | | | | | | | | | |X| | | | | | | | | | | | >>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| >>>>>>> | | | | | | | | | | | | | | | | | | | | | | >>>>>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| >>>>>>> | | | | | | | | | | | | | | | | | | | | | | >>>>>>> +-----------------------------------------+ >>>>>>> >>>>>>> Each of my little grid cells is a 10x10 image. But that 10x10 image >>>>>>> denoted by the "X" needs to be placed in memory in the right portion of >>>>>>> the >>>>>>> 16x10 x 5x10 mosaic. So what are the strides we use for the read? Well, >>>>>>> the >>>>>>> xstride is 4 because we're making room for an alpha channel that wasn't >>>>>>> present in the file, the ystride is 640 (= 10*16*4), because each >>>>>>> scanline >>>>>>> of the little 10x10 image that you read needs to be placed on the proper >>>>>>> scanline of the 160x50 mosaic you are assembling in memory. >>>>>>> >>>>>>> -- lg >>>>>>> >>>>>>> >>>>>>> P.S. Woo-hoo for making a Rust wrapper. I think that's a totally >>>>>>> great thing. >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Oct 16, 2020, at 10:46 PM, Scott Wilson <[email protected]> >>>>>>> wrote: >>>>>>> >>>>>>> I'm experimenting with a Rust wrapper for OIIO, and had some >>>>>>> questions about the stride. >>>>>>> >>>>>>> Let's say I have an image that is 10x10 pixels, and 3 channels, and >>>>>>> 1 byte per channel. What strides would be invalid for that image? I'm >>>>>>> guessing that anything between -10 * 10 * 3 * 1 to 10 * 10 * 3 * 1 and >>>>>>> the >>>>>>> AutoStride would be valid, and everything else may try to access memory >>>>>>> that isn't initialized. Is this assumption correct, or am I missing >>>>>>> something? >>>>>>> >>>>>>> Thanks! >>>>>>> _______________________________________________ >>>>>>> Oiio-dev mailing list >>>>>>> [email protected] >>>>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Larry Gritz >>>>>>> [email protected] >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> _______________________________________________ >>>>>>> Oiio-dev mailing list >>>>>>> [email protected] >>>>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Larry Gritz >>>>>>> [email protected] >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> _______________________________________________ >>>>>>> Oiio-dev mailing list >>>>>>> [email protected] >>>>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>>>>> >>>>>> _______________________________________________ >>>>>> Oiio-dev mailing list >>>>>> [email protected] >>>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>>>> >>>>>> >>>>>> -- >>>>>> Larry Gritz >>>>>> [email protected] >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> Oiio-dev mailing list >>>>>> [email protected] >>>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>>>> >>>>> _______________________________________________ >>>>> Oiio-dev mailing list >>>>> [email protected] >>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>>> >>>> _______________________________________________ >>>> Oiio-dev mailing list >>>> [email protected] >>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>> >>> _______________________________________________ >>> Oiio-dev mailing list >>> [email protected] >>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>> >>> >>> -- >>> Larry Gritz >>> [email protected] >>> >>> >>> >>> >>> _______________________________________________ >>> Oiio-dev mailing list >>> [email protected] >>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>> >> _______________________________________________ >> Oiio-dev mailing list >> [email protected] >> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >> > _______________________________________________ > Oiio-dev mailing list > [email protected] > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >
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