Problems with AllegroGL tga loading and usage.

Problems with AllegroGL tga loading and usage.

Albin Engström

Member #8,110

December 2006

RAWR! me angry.

anyway: i'm having a problem with loading tga files and using them, the problem is that the alpha channeled pixels are replaced with solid white when i create the texture.(i think, or it could be that i don't save the tga files properly, gah, it could be anything!).

Any ideas of why this might happen??
(see the attachments)

GullRaDriel

Member #3,861

September 2003

You are not loading the texture correctly.

Show us your loading tga code and your display code (both allegro && allegro_gl). Or attach a full example that we can work on.

~~Hah, myself having the same problem and it was solved: Blitting TGA with ALPHA channel (OGL)Read the thread, the answer is inside.~~

It is a matter of how you load && display.
_
EDIT:

1/* init gfx code should have this inside */
2 
          allegro_gl_use_alpha_channel( TRUE );
          glBlendFunc( GL_SRC_ALPHA, GL_ONE );
5 
       
7/*display code should look like this*/
              /* binding the texture */
              glBindTexture( GL_TEXTURE_2D, mytexture );
10 
              glEnable( GL_BLEND );
12 
              glBegin( GL_QUADS );
              /*If we set the color to white here, then the textured quad won't be*/
              /*tinted red or half-see-through or something when we draw it based on*/
              /*the last call to glColor*().*/
              glColor3f( r, g, b );
18 
              /*Draw our four points, clockwise.*/
              glTexCoord2f( 0, 1 );
              glVertex3f( x, y, 0 );
              glTexCoord2f( 1, 1 );
              glVertex3f( x + w, y, 0 );
              glTexCoord2f( 1, 0 );
              glVertex3f( x + w, y + h, 0 );
              glTexCoord2f( 0, 0 );
              glVertex3f( x, y + h , 0 );
              glEnd();
29 
              glDisable( GL_BLEND );
31 
32 
              /*binding the default texture*/
              glBindTexture( GL_TEXTURE_2D, 0 );
              
              allegro_gl_flip();

"Code is like shit - it only smells if it is not yours"
Allegro Wiki, full of examples and articles !!

Milan Mimica

Member #3,877

September 2003

allegro_gl_make_texture_ex(AGL_TEXTURE_HAS_ALPHA | AGL_TEXTURE_RESCALE, bmp, GL_RGBA8);

make sure that bmp is 32 bpp color depth.

--
M.M.
http://sparklet.sf.net

GullRaDriel

Member #3,861

September 2003

(*spr) -> handles[ it ] = allegro_gl_make_texture( (*spr) -> spr[ it ] );

Is working like a charm for me, using the sets I gave before.

"Code is like shit - it only smells if it is not yours"
Allegro Wiki, full of examples and articles !!

Archon

Member #4,195

January 2004

Do you need to turn on GL_ALPHA_TEST ?

GullRaDriel

Member #3,861

September 2003

Yes.

"Code is like shit - it only smells if it is not yours"
Allegro Wiki, full of examples and articles !!

Milan Mimica

Member #3,877

September 2003

Also, since AGL 0.4.1: you can do:

bmp = load_tga();
allegro_gl_set_video_bitmap_format(GL_RGBA8);
vbmp = create_video_bitmap(bmp->w, bmp->h);
blit(bmp, vbmp, 0, 0, 0, 0, vbmp->w, vbmp->h);
set_alpha_blender();
draw_trans_sprite(screen, vbmp, x, y);

--
M.M.
http://sparklet.sf.net

GullRaDriel

Member #3,861

September 2003

Nice trick , I take note

Albin: Is it working now ?

"Code is like shit - it only smells if it is not yours"
Allegro Wiki, full of examples and articles !!

Albin Engström

Member #8,110

December 2006

No, it isn't :/, i'm going to rewrite the whole thing and then i'll write here again.