I would like to create a simple program using SDL. I've read this page http://dblog.aldacron.net/derelict-help/using-derelict/ and this one http://code.dlang.org/about and decided that using 'dub' would be the sensible option for a beginner so I downloaded the dub executable and put it in the same directory as my source file 'test.d'.

As per the example at the above url, I created a dub.json file in the same directory with contents as so:

"dependencies": {
"derelict-sdl2":"~>1.0.0",
"derelict-gl3":"~master",
}

If I have the relevant import statements in test.d, am I right in thinking I can use dub to build my program (not just download and build the derelict libraries)? The command dub build test.d gives me a 'failed to load package' error.

I'm using 32 bit Linux.

Any help appreciated :D

Paul

On Wednesday, 19 November 2014 at 09:12:52 UTC, Paul wrote:
> I would like to create a simple program using SDL. I've read this page http://dblog.aldacron.net/derelict-help/using-derelict/ and this one http://code.dlang.org/about and decided that using 'dub' would be the sensible option for a beginner so I downloaded the dub executable and put it in the same directory as my source file 'test.d'.
>
> As per the example at the above url, I created a dub.json file in the same directory with contents as so:
>
> "dependencies": {
> "derelict-sdl2":"~>1.0.0",
> "derelict-gl3":"~master",
> }
>
> If I have the relevant import statements in test.d, am I right in thinking I can use dub to build my program (not just download and build the derelict libraries)? The command dub build test.d gives me a 'failed to load package' error.
>
> I'm using 32 bit Linux.
>
> Any help appreciated :D
>
> Paul


Dub will download and build the D packages from code.dlang.org.

However, some D packages require you to download compiled
libraries they link to for your syste. (or build them yourself
from source)

For sdl2 on linux, you need to go to:
https://www.libsdl.org/download-2.0.php and download the source.
Compile those libs using ($ ./configure; make; make install;)
Put them into a place your linker can find (usually /usr/lib/
iirc).

I believe that should work for you!

On Wednesday, 19 November 2014 at 09:12:52 UTC, Paul wrote:
> I would like to create a simple program using SDL. I've read this page http://dblog.aldacron.net/derelict-help/using-derelict/ and this one http://code.dlang.org/about and decided that using 'dub' would be the sensible option for a beginner so I downloaded the dub executable and put it in the same directory as my source file 'test.d'.
>
> As per the example at the above url, I created a dub.json file in the same directory with contents as so:
>
> "dependencies": {
> "derelict-sdl2":"~>1.0.0",
> "derelict-gl3":"~master",
> }
>
> If I have the relevant import statements in test.d, am I right in thinking I can use dub to build my program (not just download and build the derelict libraries)? The command dub build test.d gives me a 'failed to load package' error.
>
> I'm using 32 bit Linux.
>
> Any help appreciated :D
>
> Paul

could you give some more details? Full package.json, the file-structure of your project and the full output from dub would help.

> Put them into a place your linker can find (usually /usr/lib/
> iirc).

I forgot, I'm pretty sure make install does that step for you.

On 11/19/2014 6:12 PM, Paul wrote:
> I would like to create a simple program using SDL. I've read this page
> http://dblog.aldacron.net/derelict-help/using-derelict/ and this one
> http://code.dlang.org/about and decided that using 'dub' would be the
> sensible option for a beginner so I downloaded the dub executable and
> put it in the same directory as my source file 'test.d'.

It doesn't need to be in the same directory as the source. Put it somewhere on the global path.

>
> As per the example at the above url, I created a dub.json file in the
> same directory with contents as so:
>
> "dependencies": {
> "derelict-sdl2":"~>1.0.0",
> "derelict-gl3":"~master",
> }

You shouldn't be depending on ~master for anything anymore. The newest version of dub will complain about dependencies on git branches. For derelict-gl3, you can use >=1.0.0.

>
> If I have the relevant import statements in test.d, am I right in
> thinking I can use dub to build my program (not just download and build
> the derelict libraries)?

Yes, assuming that your dub.json is properly configured.

> The command dub build test.d gives me a 'failed
> to load package' error.

That's the right command, but the wrong parameters. If you are going to pass a parameter to the build command, it should be the name of a dub package, not the name of a file. Typically, you don't need to pass it a package name if all is properly configured.

Try this:

1 -- make sure dub is on the global path.

2 --
mkdir dubtest
cd dubtest
dub init

You should see the following output in side the dubtest dir

-dub.json
---source
-----app.d

3 --
Edit dub.json and add the following dependencies:

"derelict-sdl2":"~>1.0.0",
"derelict-gl3":">=1.0.0"

4 --
Edit app.d to look like this:

import derelict.opengl3.gl3,
       derelict.sdl2.sdl;

void main()
{
    DerelictGL3.load();
    DerelictSDL2.load();

    import std.stdio : writeln;
    writeln( "Success!");
}

5--
Execute the following command:
dub

You'll see some messages about fetching and building the Derelict packages and then, assuming you have SDL2 and OpenGL on your system library search path, you should see it print "Success!". Otherwise, you'll get a DerelictException of one kind or another.

Note that I didn't give dub a command option. Executing 'dub' with no options will cause it to build and run whatever package is in the current directory. By default, dub will look for source/app.d if you don't configure something differently in dub.json.

Executing 'dub build' will build the executable, but will not run it.

@wobbles:

Sorry, should have said, I built SDL and the libraries are installed in /usr/local/lib

> could you give some more details? Full package.json, the file-structure of your project and the full output from dub would help.

@John Colvin
The entire contents of dub.json are as above. My program is a single file just to check that I can init SDL:

import std.stdio;
import derelict.sdl2.sdl;
void main(){

    // Load the SDL 2 library.
    DerelictSDL2.load();

    //init SDL
    .....

}



The error is:

Error executing command build: Failed to load package at /home/paul/D-programs/: Expected end of string after JSON value, not ': {
"derelict-sdl2":"~>1.0.0",
"derelict-gl3":"~master",
}'.


TIA

On Wednesday, 19 November 2014 at 10:09:55 UTC, Paul wrote:
> @wobbles:
>
> Sorry, should have said, I built SDL and the libraries are installed in /usr/local/lib
>
>> could you give some more details? Full package.json, the file-structure of your project and the full output from dub would help.
>
> @John Colvin
> The entire contents of dub.json are as above. My program is a single file just to check that I can init SDL:
>
> import std.stdio;
> import derelict.sdl2.sdl;
> void main(){
>
>     // Load the SDL 2 library.
>     DerelictSDL2.load();
>
>     //init SDL
>     .....
>
> }
>
>
>
> The error is:
>
> Error executing command build: Failed to load package at /home/paul/D-programs/: Expected end of string after JSON value, not ': {
> "derelict-sdl2":"~>1.0.0",
> "derelict-gl3":"~master",
> }'.
>
>
> TIA

your dub.json is invalid. Please see http://code.dlang.org/package-format

I'm not sure what the exact requirements are for a minimal dub.json, but you should at very least have a name. Also, watch out for where your source files are: dub expects them in a source/ or src/ folder by default, you can change this by setting sourcePaths in your dub.json

On Wednesday, 19 November 2014 at 10:07:56 UTC, Mike Parker wrote:
> On 11/19/2014 6:12 PM, Paul wrote:
>> I would like to create a simple program using SDL. I've read this page
>> http://dblog.aldacron.net/derelict-help/using-derelict/ and this one
>> http://code.dlang.org/about and decided that using 'dub' would be the
>> sensible option for a beginner so I downloaded the dub executable and
>> put it in the same directory as my source file 'test.d'.
>
> It doesn't need to be in the same directory as the source. Put it somewhere on the global path.
>
>>
>> As per the example at the above url, I created a dub.json file in the
>> same directory with contents as so:
>>
>> "dependencies": {
>> "derelict-sdl2":"~>1.0.0",
>> "derelict-gl3":"~master",
>> }
>
> You shouldn't be depending on ~master for anything anymore. The newest version of dub will complain about dependencies on git branches. For derelict-gl3, you can use >=1.0.0.
>
>>
>> If I have the relevant import statements in test.d, am I right in
>> thinking I can use dub to build my program (not just download and build
>> the derelict libraries)?
>
> Yes, assuming that your dub.json is properly configured.
>
>> The command dub build test.d gives me a 'failed
>> to load package' error.
>
> That's the right command, but the wrong parameters. If you are going to pass a parameter to the build command, it should be the name of a dub package, not the name of a file. Typically, you don't need to pass it a package name if all is properly configured.
>
> Try this:
>
> 1 -- make sure dub is on the global path.
>
> 2 --
> mkdir dubtest
> cd dubtest
> dub init
>
> You should see the following output in side the dubtest dir
>
> -dub.json
> ---source
> -----app.d
>
> 3 --
> Edit dub.json and add the following dependencies:
>
> "derelict-sdl2":"~>1.0.0",
> "derelict-gl3":">=1.0.0"
>
> 4 --
> Edit app.d to look like this:
>
> import derelict.opengl3.gl3,
>        derelict.sdl2.sdl;
>
> void main()
> {
>     DerelictGL3.load();
>     DerelictSDL2.load();
>
>     import std.stdio : writeln;
>     writeln( "Success!");
> }
>
> 5--
> Execute the following command:
> dub
>
> You'll see some messages about fetching and building the Derelict packages and then, assuming you have SDL2 and OpenGL on your system library search path, you should see it print "Success!". Otherwise, you'll get a DerelictException of one kind or another.
>
> Note that I didn't give dub a command option. Executing 'dub' with no options will cause it to build and run whatever package is in the current directory. By default, dub will look for source/app.d if you don't configure something differently in dub.json.
>
> Executing 'dub build' will build the executable, but will not run it.


Thank you Mike, that works perfectly and pretty easy when you know how - something else that is making D feel very comfortable!

For anyone else reading this... app.d is in the /source directory created after executing 'dub init' and 'dub' or 'dub build' needs to be run from the project file (the directory containing the dub.json file and /source subdirectory). Both pretty obvious but just in case ;)

Thanks John, your tip about dub.json noted!

On Wednesday, 19 November 2014 at 10:07:56 UTC, Mike Parker wrote:
> On 11/19/2014 6:12 PM, Paul wrote:
>> I would like to create a simple program using SDL. I've read this page
>> http://dblog.aldacron.net/derelict-help/using-derelict/ and this one
>> http://code.dlang.org/about and decided that using 'dub' would be the
>> sensible option for a beginner so I downloaded the dub executable and
>> put it in the same directory as my source file 'test.d'.
>
> It doesn't need to be in the same directory as the source. Put it somewhere on the global path.
>
>>
>> As per the example at the above url, I created a dub.json file in the
>> same directory with contents as so:
>>
>> "dependencies": {
>> "derelict-sdl2":"~>1.0.0",
>> "derelict-gl3":"~master",
>> }
>
> You shouldn't be depending on ~master for anything anymore. The newest version of dub will complain about dependencies on git branches. For derelict-gl3, you can use >=1.0.0.
>
>>
>> If I have the relevant import statements in test.d, am I right in
>> thinking I can use dub to build my program (not just download and build
>> the derelict libraries)?
>
> Yes, assuming that your dub.json is properly configured.
>
>> The command dub build test.d gives me a 'failed
>> to load package' error.
>
> That's the right command, but the wrong parameters. If you are going to pass a parameter to the build command, it should be the name of a dub package, not the name of a file. Typically, you don't need to pass it a package name if all is properly configured.
>
> Try this:
>
> 1 -- make sure dub is on the global path.
>
> 2 --
> mkdir dubtest
> cd dubtest
> dub init
>
> You should see the following output in side the dubtest dir
>
> -dub.json
> ---source
> -----app.d
>
> 3 --
> Edit dub.json and add the following dependencies:
>
> "derelict-sdl2":"~>1.0.0",
> "derelict-gl3":">=1.0.0"
>
> 4 --
> Edit app.d to look like this:
>
> import derelict.opengl3.gl3,
>        derelict.sdl2.sdl;
>
> void main()
> {
>     DerelictGL3.load();
>     DerelictSDL2.load();
>
>     import std.stdio : writeln;
>     writeln( "Success!");
> }
>
> 5--
> Execute the following command:
> dub
>
> You'll see some messages about fetching and building the Derelict packages and then, assuming you have SDL2 and OpenGL on your system library search path, you should see it print "Success!". Otherwise, you'll get a DerelictException of one kind or another.
>
> Note that I didn't give dub a command option. Executing 'dub' with no options will cause it to build and run whatever package is in the current directory. By default, dub will look for source/app.d if you don't configure something differently in dub.json.
>
> Executing 'dub build' will build the executable, but will not run it.

This is a tad off topic now but I'm struggling to get a window on screen as SDL_CreateWindow is failing, here's what I've got:

try{
	DerelictSDL2.load();
}catch(Exception e){
	writeln("Failed to load DerelictSDL2 :( %s", e.msg);
	return;
}

try{
	SDL_Init(SDL_INIT_EVERYTHING);
}catch(Exception e){
	 writeln("Can't init SDL :( %s", e.msg);
	 return;
}


SDL_Window *testWindow;
//temporary magic numbers ahoy
testWindow = SDL_CreateWindow( "Test Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 800, 600, SDL_WINDOW_RESIZABLE );
if( testWindow == null ) {
	writeln("Window could not be created!");
	return;
} 	else {
	SDL_Surface* testSurface;
	testSurface = SDL_GetWindowSurface(testWindow);
}

Everything seems to initialise ok but SDL_CreateWindow always returns null. For some reason I can't use DerelictException which I guess might help me dig deeper. AFAIK there are no issues with this machine's hardware - I can certainly run other SDL-based apps on it.

On 11/21/2014 5:57 AM, Paul wrote:

>
> This is a tad off topic now but I'm struggling to get a window on screen
> as SDL_CreateWindow is failing, here's what I've got:
>
> try{
>      DerelictSDL2.load();
> }catch(Exception e){
>      writeln("Failed to load DerelictSDL2 :( %s", e.msg);
>      return;
> }

Before getting to your issue, I'd like to point out that this is a needless redundancy. You are adding anything by catching an exception here and printing to the console that the library didn't load. The exception message will tell you that already. I suggest you just remove the try..catch and let the exception propagate. The only reason to catch a DerelictException here is if you want to do something other than print the message to the console, like display a message box or write to a log file.


>
> try{
>      SDL_Init(SDL_INIT_EVERYTHING);
> }catch(Exception e){
>       writeln("Can't init SDL :( %s", e.msg);
>       return;
> }
>

SDL_Init isn't goint to throw an exception. It can't. It's a function in a C library and C doesn't know anything about D exceptions. If you look at the documentation for SDL_Init[1], you will find that it returns a negative number on failure and 0 on success.

if( SDL_Init( SDL_INIT_EVERYTHING ) < 0 ) {
 // See below for how to handle this
}

>
> SDL_Window *testWindow;
> //temporary magic numbers ahoy
> testWindow = SDL_CreateWindow( "Test Window", SDL_WINDOWPOS_UNDEFINED,
> SDL_WINDOWPOS_UNDEFINED, 800, 600, SDL_WINDOW_RESIZABLE );
> if( testWindow == null ) {
>      writeln("Window could not be created!");
>      return;
> }     else {
>      SDL_Surface* testSurface;
>      testSurface = SDL_GetWindowSurface(testWindow);
> }
>
> Everything seems to initialise ok but SDL_CreateWindow always returns
> null. For some reason I can't use DerelictException which I guess might
> help me dig deeper. AFAIK there are no issues with this machine's
> hardware - I can certainly run other SDL-based apps on it.
>

Again, DerelictExceptions aren't going to help you here. They are only thrown when the load function fails (to manipulate a DerelictException directly, import derelict.util.exception.) To get an error message out of SDL, you need to call SDL_GetError, which returns a const( char )*.

void printSDLError( string msg ) {
  import std.conv : to;
  import std.stdio : writefln;

  writefln("%s: %s", msg, to!string( SDL_GetError() ));
}

...
if( testWindow == null )
{
  printSDLError( "Failed to create window." );
  return;
}

I prefer to wrap it up in a subclass of Error. Others may prefer Exception, but when I throw an SDLError I don't intend to catch it. I really want the app to exit.

class SDLError : Error
{
    public static string errStr() @property
    {
        import std.conv : to;
        import derelict.sdl2.sdl : SDL_GetError;
        return to!string( SDL_GetError() );
    }

    public this( string msg, string file = __FILE__, size_t line = __LINE__ )
    {
        import std.string : format;

        auto fmsg = format( "%s: %s", msg, errStr );
        super( fmsg, file, line );
    }
}

Now it becomes:

DerelictSDL2.load();

if( SDL_Init( SDL_INIT_EVERYTHING ) < 0 )
{
  throw new SDLError( "Failed to initialize SDL" );
}

testWindow = SDL_CreateWindow( ... );
if( !testWindow )
{
  throw new SDLError( "Failed to create window" );
}

Whichever approach you choose, SDL_GetError will shed light on why any SDL call failed as long as you call it immediately upon failure.

[1] https://wiki.libsdl.org/SDL_Init?highlight=%28%5CbCategoryInit%5Cb%29%7C%28CategoryEnum%29%7C%28CategoryStruct%29