* AdaSDL and glTexImage2D
@ 2003-01-29 10:09 Stefan Soos
2003-01-29 20:15 ` Chad R. Meiners
0 siblings, 1 reply; 3+ messages in thread
From: Stefan Soos @ 2003-01-29 10:09 UTC (permalink / raw)
Hello,
I'm doing some programming in Ada with the thin binding to the SDL
library. I'd like to create some textured objects, but there I run
into some problems. My texture data is stored in an SDL surface:
Image : SDL.Video.Surface_ptr;
The actual data can be read from Image.Pixels. Now, I'd like to call
glTexImage2D:
glTexImage2D (GL_TEXTURE_2D,
0,
GLint (GL_RGBA),
GLsizei (Width), GLsizei (Height),
0,
GL_RGBA,
GL_UNSIGNED_BYTE,
GLubyte_Array (Image.Pixels));
but this doesn't work. How can I convert Image.Pixels (wich is
actually defined as System.Address) to an array of GLubyte?
Thanks in advance and bye,
Stefan
--
include/asm-mips64/unistd.h:
/* These are here for sake of fucking
lusercode living in the fucking believe
having to fuck around with the syscall interface themselfes. */
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: AdaSDL and glTexImage2D
2003-01-29 10:09 AdaSDL and glTexImage2D Stefan Soos
@ 2003-01-29 20:15 ` Chad R. Meiners
2003-01-30 9:52 ` Stefan Soos
0 siblings, 1 reply; 3+ messages in thread
From: Chad R. Meiners @ 2003-01-29 20:15 UTC (permalink / raw)
"Stefan Soos" <stefan.soos@gmx.de> wrote in message
news:49981b.cu.ln@ID-soos.user.dfncis.de...
>
> Hello,
>
> I'm doing some programming in Ada with the thin binding to the SDL
> library. I'd like to create some textured objects, but there I run
> into some problems. My texture data is stored in an SDL surface:
>
> Image : SDL.Video.Surface_ptr;
>
> The actual data can be read from Image.Pixels. Now, I'd like to call
> glTexImage2D:
> glTexImage2D (GL_TEXTURE_2D,
> 0,
> GLint (GL_RGBA),
> GLsizei (Width), GLsizei (Height),
> 0,
> GL_RGBA,
> GL_UNSIGNED_BYTE,
> GLubyte_Array (Image.Pixels));
> but this doesn't work. How can I convert Image.Pixels (wich is
> actually defined as System.Address) to an array of GLubyte?
Well what you want to do is bit more complicated than what a simple type
conversion function can do for you automatically.
Image.Pixels is of type System.address. First System.Address doesn't have
any bounds information, but there is hope because Ada gives you a very nice
package called System.Address_To_Access_Conversions. This package is IMHO a
very cool package because it lets you transform System.Address into any type
you would like. However invoking it in this case will be a little bit
tricky since your array will need bounds information added to it. I don't
have immediate access to the GL libraries so I can't give you the exact code
to solve your problem, but I can point you to an example in the AdaSDL thick
binding where a similar conversion takes place.
In AdaSDL-Video-Drawing.adb around line 273 you will find:
declare
subtype Current_Screen is Screen_Eight(1..Array_Size);
package Convert is new System.Address_To_Access_Conversions
(Current_Screen);
begin
Eight_Bit_Draw
( On => Convert.To_Pointer (Item.Item.Pixels).all, -- The
important conversion
Colors => To_Palette_Provider (Item),
Coordinates => Coords);
end;
Here is a example of converting the Image.Pixels (in this case
Item.Item.Pixels ;) into an access to an array of size Array_Size. Notice
that we had to declare a subtype of the Screen_Eight array with a specified
range so that the compiler can reconstruct the range information.
Now I am guessing that GLubyte_Array is an array of bytes. So for your code
your solution might look like this
declare
Bytes_Per_Pixel : constant := 4; -- I believe RGBA is 32 bit color, but
if I am wrong in your case change this value
subtype Current_Buffer is
GLubyte_Array(0..(Width*Height*Bytes_Per_Pixel)-1);
package Convert is new
System.Address_To_Access_Conversions(Current_Buffer);
begin
glTexImage2D (GL_TEXTURE_2D,
0,
GLint (GL_RGBA),
GLsizei (Width), GLsizei (Height),
0,
GL_RGBA,
GL_UNSIGNED_BYTE,
Convert.To_Pointer (Image.Pixels).all);
end;
Now remember this might need some tinkering to get it right since I don't
have the packages to test this out.
I hope this solves your problem,
Chad R. Meiners
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: AdaSDL and glTexImage2D
2003-01-29 20:15 ` Chad R. Meiners
@ 2003-01-30 9:52 ` Stefan Soos
0 siblings, 0 replies; 3+ messages in thread
From: Stefan Soos @ 2003-01-30 9:52 UTC (permalink / raw)
Hello,
On Wed, 29 Jan 2003 15:15:44 -0500, Chad R. Meiners wrote:
> In AdaSDL-Video-Drawing.adb around line 273 you will find:
> declare
> subtype Current_Screen is Screen_Eight(1..Array_Size);
> package Convert is new System.Address_To_Access_Conversions
> (Current_Screen);
> begin
> Eight_Bit_Draw
> ( On => Convert.To_Pointer (Item.Item.Pixels).all, -- The
> important conversion
> Colors => To_Palette_Provider (Item),
> Coordinates => Coords);
> end;
>
> Here is a example of converting the Image.Pixels (in this case
> Item.Item.Pixels ;) into an access to an array of size Array_Size. Notice
> that we had to declare a subtype of the Screen_Eight array with a specified
> range so that the compiler can reconstruct the range information.
I've only looked at the thin binding in adsdl.ad[bs] and
adsdl_framebuf and there he's doing some tricky stuff with
SDL.Types.Uint[8|16|32]_Ptrs. I've seen the package
Address_To_Access_Conversions in varios sources before but I didn't
know what it was good for ;)
> Now I am guessing that GLubyte_Array is an array of bytes. So for your code
> your solution might look like this
>
> declare
> Bytes_Per_Pixel : constant := 4; -- I believe RGBA is 32 bit color, but
> if I am wrong in your case change this value
> subtype Current_Buffer is
> GLubyte_Array(0..(Width*Height*Bytes_Per_Pixel)-1);
> package Convert is new
> System.Address_To_Access_Conversions(Current_Buffer);
> begin
> glTexImage2D (GL_TEXTURE_2D,
> 0,
> GLint (GL_RGBA),
> GLsizei (Width), GLsizei (Height),
> 0,
> GL_RGBA,
> GL_UNSIGNED_BYTE,
> Convert.To_Pointer (Image.Pixels).all);
> end;
That's exactly how it works. Thank you very much.
The Bytes_Per_Pixel information is stored in Image.format.BytesPerPixel.
> Now remember this might need some tinkering to get it right since I don't
> have the packages to test this out.
There was a little bit of tinkering because I have to do some color
conversion and flipping of the textures but your code worked just
right out of the box ;) Again, thank you so much.
> I hope this solves your problem,
>
> Chad R. Meiners
Indeed, it did. Thanks and bye,
Stefan
--
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2003-01-30 9:52 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2003-01-29 10:09 AdaSDL and glTexImage2D Stefan Soos
2003-01-29 20:15 ` Chad R. Meiners
2003-01-30 9:52 ` Stefan Soos
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox