OpenEuphoria

1. Blank Window (Tile Engine)

• Posted by Icy_Viking Apr 22, 2023
• 827 views

Hello,

I'm wondering if anyone could help with this. When I tried making an example using my Tile Engine wrapper. The image/background that is supposed to appear doesn't show up. The window comes up with just a blank screen. I have what I have written so far bundled in zip file. The wrapper isn't finished just yet, but very close. Other things that might help I'm using the 32-bit DLL and using Windows 11 Pro and Euphoria 4.1.0 Beta 2 32-Bit.

https://katfile.com/9ie8g3zj4l8t/te.zip.html - Wrapped so far

https://github.com/megamarc/Tilengine - In case it is needed.

// Simple C Example, converted to Eu code below 
#include "Tilengine.h" 
 
void main(void) { 
    TLN_Tilemap foreground; 
 
    TLN_Init (400, 240, 1, 0, 0); 
    foreground = TLN_LoadTilemap ("assets/sonic/Sonic_md_fg1.tmx", NULL); 
    TLN_SetLayerTilemap (0, foreground); 
 
    TLN_CreateWindow (NULL, 0); 
    while (TLN_ProcessWindow()) { 
        TLN_DrawFrame (0); 
    } 
 
    TLN_DeleteTilemap (foreground); 
    TLN_Deinit (); 
} 

include std/ffi.e 
 
include tilengine.e 
 
TLN_Init(400,240,1,0,0) 
 
atom fg = TLN_LoadTilemap("Sonic_md_fg1.tmx","") 
 
? fg 
 
TLN_SetLayerTilemap(0,fg) 
 
TLN_CreateWindow("",0) 
 
while TLN_ProcessWindow() do 
	TLN_DrawFrame(0) 
end while 
 
TLN_DeleteTilemap(fg) 
TLN_Deinit() 
 

3. Re: Blank Window (Tile Engine)

• Posted by Icy_Viking Apr 22, 2023
• 768 views

In the C code it is declared as a string and I wrapped using the C_STRING keyword.

5. Re: Blank Window (Tile Engine)

• Posted by irv Apr 23, 2023
• 717 views

What is this C_STRING keyword?

I thought we had to use allocate_string() for that.

7. Re: Blank Window (Tile Engine)

• Posted by ghaberek (admin) Apr 24, 2023
• 697 views

As Irv pointed out there is absolutely a distinction between NULL and a pointer to an empty string. The latter has a value while the former does not. Unfortunately some C libraries will double-check if strings are NULL or empty but just as many will accept an empty string as a valid string (because it is) and the resulting behavior may be different or altogether broken. Typically, C string parameter that can accept NULL should be specified as an object parameter in the Euphoria wrapper, so that it can accept NULL when necessary and treat empty strings separately.

I'm working on baking C_STRING (and C_WSTRING) into std/ffi.e so we can avoid a bunch of repetitive boilerplate code like this:

constant _wrapper_func = define_c_func( lib, "wrapper_func", {C_POINTER,C_POINTER}, C_POINTER ) 
 
public function wrapper_func( object required_string, object optional_string=NULL ) 
    if sequence( required_string ) then 
        required_string = allocate_string( required_string, TRUE ) 
    end if 
    if sequence( optional_string ) then 
        optional_string = allocate_string( optional_string, TRUE ) 
    end if 
    return c_func( _wrapper_func, {required_string,optional_string} ) 
end function 

And instead just pass the values and let c_func() handle the allocate/free as necessary:

constant _wrapper_func = define_c_func( lib, "wrapper_func", {C_STRING,C_STRING}, C_POINTER ) 
 
public function wrapper_func( object required_string, object optional_string=NULL ) 
    return c_func( _wrapper_func, {required_string,optional_string} ) 
end function 

However, this feature will gladly ignore any atom it receives and pass it along verbatim, which will respect NULL as NULL and also so you can allocate your own strings and pass them along. This would be useful for pre-allocating strings, such as preloading resources from a file or to avoid the overhead of repetitive memory allocation. I will be notating all of this in my documentation for std/ffi.e as well as adding a "mini-guide" to the docs for tips on wrapping C libraries and structures. The guide is mostly going to be written by way of collecting these recent conversations into a more concise format.

-Greg

9. Re: Blank Window (Tile Engine)

• Posted by ghaberek (admin) Apr 25, 2023
• 660 views

As a test, I ported Tutorial.c to Euphoria and got the same problem. When I checked the result of TLN_SetLayerTilemap() it was returning zero, so I grabbed the last error and printed it out:

atom tilemap = TLN_LoadTilemap( "assets/sonic/Sonic_md_fg1.tmx" ) 
 
if not TLN_SetLayerTilemap( 0, tilemap ) then 
    integer errno = TLN_GetLastError() 
    sequence errmsg = TLN_GetErrorString( errno ) 
    printf( 2, "Error %d: %s\n", {errno,errmsg} ) 
end if 

Tilengine v2.14.0 64-bit built Feb  1 2023 19:08:33 
Error 6: Invalid Tileset reference 

I think you need to all of the assets as they seem to reference each other. You'd probably have to open them with Tiled to see what-references-what since the content is all base64/zlib encoded.

Once I extracted the entire assets directory and updated the path to "assets/sonic/Sonic_md_fg1.tmx" your demo worked correctly. At the very least, you probably need the contents of the sonic folder.

-Greg

11. Re: Blank Window (Tile Engine)

• Posted by katsmeow Apr 26, 2023
• 610 views

Nevermind.

Kat