Problems with AllegroGL tga loading and usage.
Albin Engström

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

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 
3 allegro_gl_use_alpha_channel( TRUE );
4 glBlendFunc( GL_SRC_ALPHA, GL_ONE );
5 
6
7/*display code should look like this*/
8 /* binding the texture */
9 glBindTexture( GL_TEXTURE_2D, mytexture );
10 
11 glEnable( GL_BLEND );
12 
13 glBegin( GL_QUADS );
14 /*If we set the color to white here, then the textured quad won't be*/
15 /*tinted red or half-see-through or something when we draw it based on*/
16 /*the last call to glColor*().*/
17 glColor3f( r, g, b );
18 
19 /*Draw our four points, clockwise.*/
20 glTexCoord2f( 0, 1 );
21 glVertex3f( x, y, 0 );
22 glTexCoord2f( 1, 1 );
23 glVertex3f( x + w, y, 0 );
24 glTexCoord2f( 1, 0 );
25 glVertex3f( x + w, y + h, 0 );
26 glTexCoord2f( 0, 0 );
27 glVertex3f( x, y + h , 0 );
28 glEnd();
29 
30 glDisable( GL_BLEND );
31 
32 
33 /*binding the default texture*/
34 glBindTexture( GL_TEXTURE_2D, 0 );
35
36 allegro_gl_flip();

Milan Mimica

allegro_gl_make_texture_ex(AGL_TEXTURE_HAS_ALPHA | AGL_TEXTURE_RESCALE, bmp, GL_RGBA8);

make sure that bmp is 32 bpp color depth.

GullRaDriel

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

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

Archon

Do you need to turn on GL_ALPHA_TEST ?

GullRaDriel

Yes.

Milan Mimica

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);

GullRaDriel

Nice trick , I take note :)

Albin: Is it working now ?

Albin Engström

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

Thread #591336. Printed from Allegro.cc