Re: "First natively compiled language with hot code-reloading at runtime"
Hey, a while back I wrote an article on this subject: [https://16bpp.net/page/hot-loading-code-in-nim](https://16bpp.net/page/hot-loading-code-in-nim) Neat work you've done though.
Geometry Library
I know there are packages out there such as `glm` (which I'm already using). But are there any good **pure Nim** packages/libraries for doing geometric computations? I'm looking to target JS.
Re: "Nim needs better documentation" - share your thoughts
I think the Leap Motion C API docs look quite nice: [https://developer.leapmotion.com/documentation/v4/index.html](https://developer.leapmotion.com/documentation/v4/index.html)
SQL modules args/string santization
I've been playing around with the db_sqlite module a bit. Looking at the procs for exec() and getRow()/getAllRows() It can take an option args parameter. are these arguments automatically sanitized for me, or do I manually need to do it myself. I'd like to avoid a "Bobby Tables" incident in the app I'm writing.
Re: "Nim needs better documentation" - share your thoughts
Hi, it's been a while since I posted here in the community (or done much with Nim), but here at least is my $0.02: I'm not a big fan right now of how inline documentation comments/strings work. 1. This may be more of a personal preference, but I don't like putting the documentation right in the body of the function. It looks like this was influenced from Python. Java, C#, C/C++ doc systems (e.g. Doxygen), Rust, Swift, PHP; only to name a few of the major languages out there, put their doc-strings right above function, not in it. 2. I would rather see a tool like Doxygen be used to generate the documentation for Nim. It's very mature, flexible, and generates easy to use docs. One other thing is that Doxygen generated docs typically are quite navigable. I find it a little hard to search through Nim's documentation a the moment. I'm not sure about the difficulty integrating the Nim language into Doxygen though
Re: Binding a JavsScript object that's not part of the DOM
Does it live update to when the style changes? That's one of the benefits CSSStyleDeclaration is that if you change the CSS for an object, you don't need to query for the style declaration again.
Binding a JavsScript object that's not part of the DOM
I'm writing an app right now and I need to figure out what the width & height of div, with it's applied CSS styling. Back in vanilla JS, there is the function [getComputedStyle()](https://developer.mozilla.org/en-US/docs/Web/API/Window/getComputedStyle) which will give me [CSSStyleDeclaration](https://developer.mozilla.org/en-US/docs/Web/API/CSSStyleDeclaration) object. That object is not part of the DOM or the BOM, it's part of the CSSOM. I don't really know how to bind this. How would I go about this?
Re: Nim and hot loading - any experiences to share?
Sorry for the belated reply. I'm a little confused at what you're trying to achieve here. Can you explain it in a few words what you want? It it something with trying to get dynamically allocated memory to place nice with hot-loaded code?
Re: Nim and hot loading - any experiences to share?
I wrote this article a while back: [https://16bpp.net/page/hot-loading-code-in-nim](https://16bpp.net/page/hot-loading-code-in-nim)
Re: Using `string` vs `seq[uint8]` for non-text data
Sorry to be a bit of a pest, but I want to know if this is the thing I should be doing or not for my Nim code now?
Re: Using `string` vs `seq[uint8]` for non-text data
Okay, that sounds better to me. So for in my case with my stb_image wrapper, should I switch the API now to use seq[byte] or should I hold off on it for a little longer?
Using `string` vs `seq[uint8]` for non-text data
This stems from some discussion I've had on the stb_image bindings: [https://gitlab.com/define-private-public/stb_image-Nim/issues/4#note_40535183](https://gitlab.com/define-private-public/stb_image-Nim/issues/4#note_40535183) I'd like some discussion on the use of the string datatype for non-text data. **I.e. using `string` as a buffer for binary data.** It's always been my impression that if a language/API provides a string datatype, that strings should only be used for text data; e.g. Qt's QString and QByteArray objects. strings typically have the notion of being data that is mean for humans to read. Where an explicit byte array should be used for non text data (e.g. image data). Even though under the hood (most of the time) there is a char *. In the issue ticket I linked, Eduardo Bart mentioned that int the Nim codebase that string is also used as a buffer (instead of a seq[uint8]), e.g. readFile() and writeFile(). Where even the data those procs could be returning binary and not text. How do others here feel about this?
Re: Killing an AsyncHttpServer
Yeah, I have the killServer = true in a block somewhere.
Adding return after server.close() does work, but I need to mark server with
{.threadsafe.}. It also causes an issue with the HTTP Request (on the browser
side) doesn't get finished and just hangs. Interestingly enough this doesn't
actually stop the application then and there. It's if I try to send a request
after killServer = true that it will end the program with this output:
Traceback (most recent call last)
Server.nim(76) Server
asyncdispatch.nim(1010) waitFor
asyncdispatch.nim(1013) poll
Error: unhandled exception: No handles or timers registered in dispatcher.
[ValueError]
Re: Killing an AsyncHttpServer
It now compiles successfully, but it doesn't seem to be killing the server when I trip that killServer block. It will run over the line and continue on with execution.
Killing an AsyncHttpServer
So I've got some code like this:
import asyncDispatch
import asynchttpserver
# Create the server object and state data
var
server = newAsyncHttpServer()
let port = 8000
# ...
proc handleRequest(req: Request) {.async.}=
## Handle an incomming connection
var killServer = false
# ...
if killServer:
server.close()
# Write a response
var headers = newHttpHeaders()
headers.add("Content-Type", "text/html")
await req.respond(Http200, mkPage(pageViews, killServer), headers)
# Handle requests
echo("Listening for connections on http://localhost:; & $port & "/")
waitFor server.serve(Port(port), handleRequest)
If I try to call server.close() I keep on getting this error:
Server.nim(74, 15) Error: type mismatch: got (AsyncHttpServer, Port, proc
(req: Request): Future[system.void]{.locks: .})
but expected one of:
proc serve(server: AsyncHttpServer; port: Port;
callback: proc (request: Request): Future[void]; address = ""):
Future[void]
I've tried creating a wrapper async function around the close call, that didn't
work. I tried using an event callback, that didn't work either. Both other
produced the same compilation errors. What's going on here?
Re: Having a hard time getting raylib bindings to work
So this is a fun issue now...
I've gotten the bindings to work, but when you want to do something with
Textures, they won't display on the screen. The raylib tracelog says everything
is okay when it came to loading the assets. I'm tracking the issue here:
[https://gitlab.com/define-private-public/raylib-Nim/issues/1](https://gitlab.com/define-private-public/raylib-Nim/issues/1)
I've tried:
* dynamically loading raylib.so at runtime, (via the dynlib pragma)
* statically linking raylib
* statically compiling the raylib source into raylib.nim (via the compile
pragma)
The only thing I can think of is that there is some issue with how c2Nim
translated the Image data structure. I think it has to do with that void *
pointer.
typedef struct Image {
void *data; // Image raw data
int width; // Image base width
int height; // Image base height
int mipmaps;// Mipmap levels, 1 by default
int format; // Data format (TextureFormat type)
} Image;
type
Image* = object
data*: pointer ## Image raw data
width*: cint ## Image base width
height*: cint ## Image base height
mipmaps*: cint ## Mipmap levels, 1 by default
format*: cint ## Data format (TextureFormat type)
Anyone got any ideas?
Re: Having a hard time getting raylib bindings to work
Taking a look [at the man page for
dlopen(3)](http://man7.org/linux/man-pages/man3/dlopen.3.html), I think the
easiest thing to do would to be to wrap the dlopen() call in the Nim code in
something that sets and then resets the LD_LIBRARY_PATH environment variable.
Taking a look at the dlopen() imports in
[dylib.nim](https://github.com/nim-lang/Nim/blob/75345ad1aacf8e2a4d43e4e89f16f6a641d6a9c3/lib/pure/dynlib.nim#L85)
and
[dyncalls.nim](https://github.com/nim-lang/Nim/blob/7e351fc7fa96b4d560c5a51118bab22abb590585/lib/system/dyncalls.nim#L67),
we could use the os modules' getEnv() and putEnv() functions.
E.g.:
from os import getEnv, putEnv
proc real_dlopen(path: cstring, mode: cint): LibHandle
{.importc: "dlopen", header: "".}
proc dlopen(path: cstring, mode: cint): LibHandle=
# Modify the library search path
var
origLibPath = getEnv("LD_LIBRARY_PATH")
newLibPath = originalLibPath & ":/usr/local/lib"
setEnv("LD_LIBRARY_PATH", newLibPath)
result = real_dlopen(path, mode)
setEnv("LD_LIBRARY_PATH", origLibPath)
I think that would do it. Looking also [at OS X's
dlopen()](https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man3/dlopen.3.html),
it might be best to add in a block that will get the correct environment
variable to get, set, and reset. Interestingly enough, OS X already searches
/usr/local/lib by defualt. But I'm not sure about /usr/local/Cellar, where is
where homebrew likes to put stuff.
I'll leave the details up to you, but I think this needs to be the case for
Linux at least.
Re: Having a hard time getting raylib bindings to work
I consider it something that Nim should be concerned about. It's already caused me a fair bit of grief trying to get the bindings working on Linux and I'm sure anyone else will run into the same issue down the road. Keep in mind it's not my .so that it was failing to find, but an .so that mine depended on, which was in a well known install location.
Re: Having a hard time getting raylib bindings to work
I think I figured out why setting export LD_LIBRARY_PATH=/usr/local/lib was necessary to make it work. [The dlopen() function](http://man7.org/linux/man-pages/man3/dlopen.3.html) is used under the hood for the dynlib macro on Linux. dlopen() will not search /usr/local/lib by default. It needs to be manually specified... Is this something that maybe should be fixed in the Nim source to also search /usr/local/lib for .so files on unix systems?
Re: Having a hard time getting raylib bindings to work
I use ubuntu (well, xubuntu... technically). I doubt it's a bug on their side. Someone else would have tripped over this way before I would have and fixed it too.
Re: Having a hard time getting raylib bindings to work
I've been able to get the Nim bindings to work on Linux using .so files!! There is still a bit of an odd quirk: 1. GLFW 3.2.1 needs to be installed (with cmake -DBUILD_SHARED_LIBS=ON) from source (sudo make install). So those get put in /usr/local/lib 2. raylib needs to be installed (with make SHARED_RAYLIB=YES) from source (sudo make install SHARED_RAYLIB=YES). Those get put in /usr/local/lib too. So at this point, you can compile the core_basic_window.nim example I have in examples. But the problem is that if I try to run it, I get this: ben@linux:examples$ ./core_basic_window /usr/local/lib/libraylib.so: undefined symbol: glfwSetWindowIcon could not load: libraylib.so But when I did export LD_LIBRARY_PATH=/usr/local/lib. then it would run fine. What the hell is going on here? Isn't /usr/local/lib one of the default library search paths? That's where the .so files are put.
Re: Having a hard time getting raylib bindings to work
I found out some more information about the issue on Linux. If you read the link to my edited post at the top it explains a little more. tl;dr the raylib.so Linux .so is broken.
Having a hard time getting raylib bindings to work
I'm trying to get some Nim bindings for [this neat little game programming
library called raylib](https://github.com/raysan5/raylib/). But well, I'm
having some difficulties trying to do so.
After cleaning up raylib.h, I was able to use c2nim to auto-generate a .nim. I
commented out a few things and added in the {.importc.} pragmas manually. You
can [see it thus far
here](https://gitlab.com/define-private-public/raylib-Nim/blob/dac2fdab777604053c470b4a41a6f9844148575b/src/raylib.nim).
If you want to help me out, you'll need to build your own copy of raylib, off
of the develop branch, using the SHARED_RAYLIB=YES option at make. There are
some extra instructions on their Wiki.
On Linux: I can't seem to get the library to load at runtime. It compiles fine.
But when I try to run the core_basic_window in examples, I keep on getting
could not load: libraylib.so messages. I tried compiling with the extra
information and it only said that it couldn't find the .so file. I tried
placing the .so in /usr/local/lib, and the current working directory (with
setting LD_LIBRARY_PATH). Still nothing. Does anyone see what's wrong here?
On OS X: It's in a partial working state. For now, the .dylib needs to be in
the same folder as the .nim you want to compile, as well as for to run the
executable. There's a bit of a problem though. It's failing to load some of the
functions from the .dylib, thus making the application crash if I don't have
that {.deadCodeElim: on.} pragma at the top of src/raylib.nim. For example, if
I remove that pragma, it will compile, but at runtime it will say could not
import: LoadMeshEx. The proc id in Nim looks fine to me. Anyone know what's
going wrong?
For Windows: I haven't tried yet. If someone else to try this out and see how
they are going, I'd be very appreciative.
Re: Games made in Nim
I made a game called "Pucker Up," for the Linux Game Jam 2017. The original entry's source can be found here: [https://gitlab.com/define-private-public/LGJ2017](https://gitlab.com/define-private-public/LGJ2017) I also was able to (with moderate ease) pull out the OpenGL & SDL2 stuff, and replace it with the necessary HTML5 things to port it to the browser using Nim's JavaScript target. You can play it here: [https://16bpp.net/games/pucker-up-lgj-2017](https://16bpp.net/games/pucker-up-lgj-2017)
Re: The Linux Game Jam 2017 - itch.io
I was looking into using that stuff to port what I did for the Game Jam to JS, but I was wondering about how to get SDL_Mixer compiled to JS.
Re: The Linux Game Jam 2017 - itch.io
Also, I can't remember who here runs the Hookrace.net blog, but they talked about how they got NimES their (Nim & SDL2 NES emulator) ported to JavaScript: [https://hookrace.net/blog/porting-nes-go-nim](https://hookrace.net/blog/porting-nes-go-nim)/
Re: The Linux Game Jam 2017 - itch.io
Also, I can't remember who here runs the Hookrace.net blog, but they talked about how they got NimES their (Nim & SDL2 NES emulator) ported to JavaScript: [https://hookrace.net/blog/porting-nes-go-nim](https://hookrace.net/blog/porting-nes-go-nim)/
Re: Mascot
> Honey badgers are admired precisely for their capacity and inclination to do > violence. A Nim honey badger should look meaner than most I'd think. Should we have it ripping apart a Snake? Or gnawing down on a Gopher?
Re: Mascot
@jester, those designs do look a lot better IMO.
Re: Mascot
Aww man, and here I was hoping for some sort of cutesy anime girl for a mascot. Oh well : P (Just kidding) I think having a mascot is a good idea, but I don't think that having him front and center everything would be good. Having the crown logo in more places would be better. I also think the mascot design is a bit overly complex right now and not that aesthetically pleasing to look at. Right now, the mascot kind of reminds me of [this](https://www.google.com/search?q=japanese+mascot+bear+with+melon+head=lnms=isch=X=2=0ahUKEwjjh4uq1d3SAhXBWCYKHUNGD6oQ_AUIBigB=1680=912). I think it would be good to make him look a bit more friendly, but [looking at other graphics of Honey Badgers](https://www.google.com/search?q=honey+badger+graphics=lnms=isch=X=0ahUKEwjhheSW1d3SAhWnyoMKHaG4BkEQ_AUIBigB=1680=912#tbm=isch=honey+badger+graphic&*) we might as go for that "bite and rip off your arm," feeling.
Re: Trouble with reading from stdin
Is it something related to stdin's default buffer size? Default is around 4096 character IIRC.
Re: Trouble with reading from stdin
When I ran a debug build, I got this stack of errors: Traceback (most recent call last) random_art.nim(185) random_art equationParser.nim(51) parseEquation equationParser.nim(73) buildEquation ModExpr.nim(72) buildMod equationParser.nim(75) buildEquation WellExpr.nim(56) buildWell equationParser.nim(79) buildEquation SinExpr.nim(84) buildSin equationParser.nim(79) buildEquation SinExpr.nim(84) buildSin equationParser.nim(75) buildEquation WellExpr.nim(56) buildWell equationParser.nim(77) buildEquation TentExpr.nim(57) buildTent equationParser.nim(73) buildEquation ModExpr.nim(73) buildMod equationParser.nim(77) buildEquation TentExpr.nim(57) buildTent equationParser.nim(73) buildEquation ModExpr.nim(73) buildMod equationParser.nim(71) buildEquation ProductExpr.nim(59) buildProduct equationParser.nim(83) buildEquation MixExpr.nim(63) buildMix equationParser.nim(83) buildEquation MixExpr.nim(64) buildMix equationParser.nim(79) buildEquation SinExpr.nim(84) buildSin equationParser.nim(83) buildEquation MixExpr.nim(63) buildMix equationParser.nim(69) buildEquation SumExpr.nim(62) buildSum equationParser.nim(77) buildEquation TentExpr.nim(57) buildTent equationParser.nim(69) buildEquation SumExpr.nim(61) buildSum equationParser.nim(67) buildEquation ConstExpr.nim(88)buildConst strutils.nim parseFloat Error: unhandled exception: invalid float: - [ValueError] But I need to reiterate, it only happens when I copy and paste into a terminal using standard input. If it's piped in, there is no error what soever and renders fine.
C#/Java like interfaces for Nim
One of my favorite things from C#/Java are interfaces and I've been trying to work on writing some macros can generate an interface and allow you to implement it. So far I've played around with getting some sort of "toy interface," working as well as some of the macros too. Here is my initial prototype code: type # The interface IWorker* = object obj*: ref RootObj setup_proc*: proc(obj: ref RootObj, a, b: float) run_proc*: proc(obj: ref RootObj) getResult_proc*: proc(obj: ref RootObj): float # A base type MathOperation = object of RootObj result: float Adder = ref object of MathOperation first, second: float Subtracter = ref object of MathOperation initial, subtraction: float # Multiplier = ref object of MathOperation #value, multiplier: float # # Divider = ref object of MathOperation #numerator, divisor: float #=== Procs for the IWorker ===# proc setup(worker: IWorker; a, b: float) = worker.setup_proc(worker.obj, a, b) proc run(worker: IWorker) = worker.run_proc(worker.obj) proc getResult(worker: IWorker): float = return worker.getResult_proc(worker.obj) #=== Procs for the Adder ===# proc Adder_setup(obj: ref RootObj; a, b: float) = var this = cast[Adder](obj) this.first = a this.second = b proc Adder_run(obj: ref RootObj) = var this = cast[Adder](obj) this.result = this.first + this.second proc Adder_getResult(obj: ref RootObj): float = var this = cast[Adder](obj) return this.result #=== Procs for the Subtractter ===# proc Subtracter_setup(obj: ref RootObj; a, b: float) = var this = cast[Subtracter](obj) this.initial = a this.subtraction = b proc Subtracter_run(obj: ref RootObj) = var this = cast[Subtracter](obj) this.result = this.initial - this.subtraction proc Subtracter_getResult(obj: ref RootObj): float = var this = cast[Subtracter](obj) return this.result var worker: IWorker # Slap together the interface add = IWorker( setup_proc: Adder_setup, run_proc: Adder_run, getResult_proc: Adder_getResult ) sub = IWorker( setup_proc: Subtracter_setup, run_proc: Subtracter_run, getResult_proc: Subtracter_getResult ) # Assign an object (the objects in this case really don't have any special data) add.obj = new(Adder) sub.obj = new(Subtracter) # Try out the workers worker = add worker.setup(10.0, 2.0) worker.run echo worker.getResult # Should be 12in worker = sub worker.setup(10.0, 2.0) worker.run echo worker.getResult # Should be 8 Right now I've got a macro called INTERFACE that acts like the one below and can produce the type object. INTERFACE IWorker ACTS_ON MathOperation: proc setup(a, b: float) proc run() proc getResult(): float # Produces this specifically: #type # # The interface # IWorker = object #obj: ref MathOperation #setup_proc: proc(obj: ref MathOperation; a, b: float) #run_proc: proc(obj: ref MathOperation) #getResult_proc: proc(obj: ref MathOperation): float But I've been doing some thinking and wondering if I should have the interface actually act on an object. This would get rid of the obj field and remove the insertion of the ref RootObj`s from the generated `type object interface. This way an interface isn't tied to working on one type of object, but instead an interface could be a "collection of functions (stored in an object) that can act on any types," instead of a "contract for operations on a specific type." I'm wondering which road I should go down. The "contract," way would closely represent how interfaces work in C#/Java, but I feel that the "collection," idea would give more flexibility to Nim. What's your input?
Re: Problems making a library and importing it
You need to add the export marker right after the proc's id. Try this: proc testEcho*() = echo "hello world" You can also drop that : void part too.
Re: Nim Podcast
Sounds like a cool idea, but I'd be interested in reading a newsletter first.
Re: Seq with custom fields
You will need to add this proc for the add:
proc add*(es: var ExtSeq; x: int) {.inline.}=
es.s.add(x)
The inline pragma isn't necessary, but it speeds things up a little.
For using the index tokens ([ and ]), you just need to override that proc too:
# Get
proc `[]`*(es: var ExtSeq; index: int) {.inline.}=
return es.s[index]
# Set
proc `[]=`*(es: var ExtSeq; index: int; value: int) {.inline.}=
es.s[index] = value
Re: Why do custom types need to be reference counted objects for dynamic dispatch to work.
Wow. Thanks for that post. I think this belongs in the docs somewhere or on a wiki. I came across this issue when I was change the prototype of a base method but forgot to change one of the child objects. So for that specific child object it was using the base method. Would using the base pragma have the Nim compiler fail if the child prototypes didn't match the parent?
Why do custom types need to be reference counted objects for dynamic dispatch to work.
Let's have a code example. When I'm using ref object of ... This code:
type
Animal = ref object of RootObj
name: string
method makeNoise(this: Animal) {.base.} =
echo "..."
type
Human = ref object of Animal
Dog = ref object of Animal
method makeNoise(this: Human) =
echo "Hi, I'm ", this.name
method makeNoise(this: Dog) =
echo "*Bark!* [said ", this.name, "]"
let
h = Human(name: "Kevin Bacon")
d = Dog(name: "Fuzzy")
h.makeNoise()
d.makeNoise()
let a:Animal = Dog(name: "Fluffy")
a.makeNoise()
Produces this result:
Hi, I'm Kevin Bacon
*Bark!* [said Fuzzy]
*Bark!* [said Fluffy]
But when we take away that ref keyword from the type lines, the output becomes
this:
Hi, I'm Kevin Bacon
*Bark!* [said Fuzzy]
...
This leads me to believe that my objects need to be reference counted to take
advantage of dynamic dispatch. Is this true?
Re: Getting a segfault when testing my C wrapper on OS X
I put the source of the header in it's own .nim file so my users wouldn't have to add a \--cincludes: option at the compilation step. I do find it odd that import had different behavior on Linux vs. OS X in regards to this, and it effected a return value.
Re: Getting a segfault when testing my C wrapper on OS X
Well, I got the unit tests run without any segfaults (on OS X). On a whim, I decided to change the import stb_image_header line (in stb_image.nim) to use the include statement instead; it worked. Is this a bug I should report?
Re: Getting a segfault when testing my C wrapper on OS X
Alright, I tried that and it does echo out a pointer address (e.g. 0xFFff08b7e). Where this is getting kind of weird for me is that I have this raytracer that I'm working on that uses stb_image.h as well and it able to load an image on OS X without throwing a seg fault. The code for the mini-wrapper is here: [https://gitlab.com/define-private-public/PeterShirley-RayTracing-Nim/blob/7130281eee79c76be8e0c6ecb6dc36c99ab5aa52/book2/stb_image.nim](https://gitlab.com/define-private-public/PeterShirley-RayTracing-Nim/blob/7130281eee79c76be8e0c6ecb6dc36c99ab5aa52/book2/stb_image.nim) The only major difference is that the wrapper in the ray tracer doesn't have the header file embedded directly in a .nim file, though that shouldn't matter. I am really perplexed by this.
Re: Getting a segfault when testing my C wrapper on OS X
It shouldn't be an issue with the test suite. I added this line right after the let data = stbi_load(... call echo x echo y echo channels_in_file echo data.repr And it gave me this output: 2 2 4 Traceback (most recent call last) tests.nim(56)tests stb_image.nim(86)load repr.nim(308)reprAny repr.nim(252)reprAux repr.nim(234)reprRef repr.nim(271)reprAux SIG SEGV: Illegal storage access. (Attempt to read from nil?) I find this very odd because the return parameters are fine, but the actual returned value is not.
Getting a segfault when testing my C wrapper on OS X
I'm working on my stb_image wrapper right now. It's almost ready for release. But to be a good little developer I want to test it on the three major platforms (Linux, OS X, and Windows) before saying it's v1.0. I developed it on Linux and it passes all of the unit tests. But when I tried to have it run on OS X (sierra), I got this error: [Suite] Unit Tests for stb_image wrapper Traceback (most recent call last) tests.nim(56)tests stb_image.nim(86)load SIGSEGV: Illegal storage access. (Attempt to read from nil?) The line in question can be found here: [https://gitlab.com/define-private-public/stb_image-Nim/blob/bd4fc301069b068d7657b838ecf369be0573683a/stb_image.nim#L86](https://gitlab.com/define-private-public/stb_image-Nim/blob/bd4fc301069b068d7657b838ecf369be0573683a/stb_image.nim#L86) I did a little investigating. The wrapped function stbi_load() is setting the width, height, and components variables like it should, but nothing is being passed into data upon the function's return. I got the same error when I tried to do this: echo data[] I really have no idea what is wrong.
Re: How to embed a header file into a .nim file
I went with yglukhov's solution (since it seemed to be the simplest to use), but It's really what I wanted to avoid doing.
Re: Return values question
Thanks for that post, it definitely gave me a lot of insight into what is going on in Nim. I'm working with a lot of pixel data and wanted to return it from a function as a seq[uint8]. I want to avoid it doing an necessary copy (on return) for a lot of data (which I assume is happening right now).
Return values question
How does Nim return values from a proc? Are basic datatypes (like int and float) returned by copy? What about more complex structures like sequences and strings? For example, would this proc: proc fillWith(n, count: int): seq[int] = var s: seq[int] = @[] for i in countup(0, count - 1): s.add(n) return s return what was instantiated on line 2? Or would it copy over the values to new sequence and return that to the caller? What about custom objects?
Best way to represent pixel data in Nim
I want to work on a [stb_image](https://github.com/nothings/stb/blob/master/stb_image.h) wrapper. I'm trying to figure out the best (and most efficient) way of storing pixel data in Nim's data structures. stb_image stores the pixel data in an unsigned char * type. I had a chat with the person who wrote the nimPNG package and he says that using Nim's string would be a good container. But when I was working with stb_image in Nim (for another project) I was using a seq[uint8] type ([thread link here](http://forum.nim-lang.org///forum.nim-lang.org/t/2638), [final mini-wrapper here](https://gitlab.com/define-private-public/PeterShirley-RayTracing-Nim/blob/77728b48a4a58a1420f1bbcef983c37284a71dcf/working/stb_image.nim). Which one would be better to work with?
Problems trying to wrap a single header file library
I'm working on porting over some ray tracing code from a C++ project. So far
things have been fine, but they used this library called
[stb_image.h](https://github.com/nothings/stb/blob/master/stb_image.h) to load
in textures.
I thought I would try to create a wrapper for the single function that is used
"stbi_load()"
So far I've got this (filename "stb_image.nim")
# This file is a wrapper of a subset for the "stb_image.h" library that is
# needed for the raytracer
# Required before including the stb_image.h header
{.emit: """
#define STB_IMAGE_IMPLEMENTATION
""".}
# Internal function
proc stbi_load(filename: cstring; x, y, comp: var cint; req_comp: cint):
cstring
{.importc: "stbi_load", header: "stb_image.h".}
## External function (the Nim friendly version)
proc stbi_load*(filename: string; x, y, comp: var int; req_comp: int):
seq[uint8] =
var
width: cint
height: cint
comp2: cint
pixelData: seq[uint8]
let data = stbi_load(filename.cstring, width, height, comp2,
req_comp.cint)
# Set the data
x = width.int
y = width.int
comp = comp2.int
newSeq(pixelData, x * y)
# TODO set the pixelData
return pixelData
I seem to be fine, until I compile and get this:
CC: stb_image
Error: execution of an external compiler program 'gcc -c -w
-I/home/ben/bin/Nim/lib -o nimcache/stb_image.o nimcache/stb_image.c' failed
with exit code: 1
nimcache/stb_image.c:10:23: fatal error: stb_image.h: No such file or
directory
compilation terminated.
I have the stb_image.h file right alongside the nim one. What should I do here?
Also, do you think the return type cstring (for the internal function) is fine?
stb_image() returns an unsigned char *. I figured casting it to a seq[uint8]
should be fine.
Bitwise operation problems.
I'm trying to map my "quadruplet" object to an unsigned 32-bit number, that is
supposed to represent an RGBA pixel. I'm able to convert my floating point
quadruplet values to their respective R, G, B, and A components, but when I try
to do an and on all of the components, I'm getting a 0. Here is my code:
proc map*(x, a, b, p, q: float): float {.inline.} =
return (x - a) * (q - p) / (b - a) + p
#...
type
# [-1, 1] -> [0x00, 0xFF]
Quadruplet* = ref object of RootObj
w*: float
x*: float
y*: float
z*: float
# ...
# Returns a quadruplet as a nicely formatted RGBA pixel. Remember:
# [-1, 1] -> [0x00, 0xFF]. Anything out of that range will be clamped
proc toRGBA*(q: Quadruplet): uint32 {.inline.} =
let
r = q.x.clamp(-1, 1).map(-1, 1, 0x00, 0xFF).uint32 shl 24
g = q.y.clamp(-1, 1).map(-1, 1, 0x00, 0xFF).uint32 shl 16
b = q.z.clamp(-1, 1).map(-1, 1, 0x00, 0xFF).uint32 shl 8
a = q.w.clamp(-1, 1).map(-1, 1, 0x00, 0xFF).uint32
pixel = r and g and b and a
echo ""
echo r
echo g
echo b
echo a
echo pixel
echo ""
return pixel
Those echo statements are in there for debugging purposes right now.
So an example call would be: echo Quadruplet(w:0, x:1, y:1, z:1).toRGBA() # 50%
white
And it's producing this on standard output
4278190080
16711680
65280
127
0
All of those components look correct, except for when I combine them with the
ands into the full pixel. Can someone explain what's wrong here and how to fix
it?
Re: Converting a nim string to a ptr GlChar
That second one "with force," is what did the trick. (That first one didn't compile). Thanks!
Converting a nim string to a ptr GlChar
Right now I'm trying to get a simple OpenGL ES example working with Nimious' GL
ES bindings. I'm hitting a bit of a wall when trying to get the proc
glShaderSource() to accept my shader's source code (which is gotten through the
readFile() proc, which outputs a nim string). Here is a link to that proc:
[https://github.com/nimious/gles/blob/master/src/gles2/gl2.nim#L1545](https://github.com/nimious/gles/blob/master/src/gles2/gl2.nim#L1545)
In C, this usually is the way someone loads a shader source:
const char* vertexShaderSrc =
"#version 400"
""
"in vec3 pos;"
""
"void main() {"
" gl_Position = vec4(pos, 1.0);"
"}";
// ...
GLuint vertShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertShader, 1, , NULL)
I'm fine up until that 3rd parameter to something that GLES' glShaderSource()
proc will accept? It needs a ptr ptr GlChar. [GlChar is defined
here](https://github.com/nimious/gles/blob/master/src/gles2/gl2.nim#L22)
Re: "Error: expression has no address" issue with an array type
Oh, did not know that. Thanks! I didn't find any mention of that in the Nim manual, it might be something to add here: [http://nim-lang.org/docs/manual.html#statements-and-expressions-the-addr-operator](http://forum.nim-lang.org///nim-lang.org/docs/manual.html#statements-and-expressions-the-addr-operator)
"Error: expression has no address" issue with an array type
Right now I'm trying to do a very tiny OpenGL in nim. I'm at the stage where I need to bind my buffer data. The compiler is giving me this error: Error: expression has no address Here is the C code I'm trying to port: float points = [ 0.0, 0.5, 0.0, 0.5, -0.5, 0.0, -0.5, -0.5, 0.0 ]; // ... GLuint vbo = 0; glGenBuffers(1, ); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, 9 * sizeof(float), points, GL_STATIC_DRAW); And here is my nim code right now: let points = [ 0.0, 0.5, 0.0, 0.5, -0.5, 0.0, -0.5, -0.5, 0.0 ] numVertexBuffers = GlSizei(1) pointsBufferSize = GlSizeiptr(sizeof(points)) # ... var vbo: GlUint glGenBuffers(numVertexBuffers, vbo.addr) glBindBuffer(GL_ARRAY_BUFFER, vbo) glBufferData(GL_ARRAY_BUFFER, pointsBufferSize, points.addr, GL_STATIC_DRAW) # It errors here on `points.addr` Here is the definition for the glBufferData() proc: [https://github.com/nimious/gles/blob/master/src/gles2/gl2.nim#L494](https://github.com/nimious/gles/blob/master/src/gles2/gl2.nim#L494) I have no idea what's wrong here.
Re: How to iterate through a file using readLine()
No, that's for the proc that returns a boolean. I meant for the one that returns a TaintedString.
Re: How to iterate through a file using readLine()
Thanks. What would readLine() return though (using the proc I linked) if it reached EOF?
How to iterate through a file using readLine()
I know that this exists to cover what I want to do: for line in lines filename: echo line But how would I go about it using the [readLine() function here](http://forum.nim-lang.org///nim-lang.org/docs/system.html#readLine,File)?
