SDL_Image, Opengl Textures & Alpha

**technomage** · 22-01-2005, 06:44 PM

Hi

Ive; written some code to load a tga file using SDL_Image and then produce a opengl texture from that. The problem I'm getting this that the alpha channel doens't seem to be coming through. the I render with the Blend functions off the texture renders OK , but with blending all I get is a black screen. :?

Here is the code

Code:

 Surface&#58;= nil;
 TempSurface &#58;= IMG_Load&#40;PChar&#40;Filename&#41;&#41;;
 if TempSurface <> nil then
 begin
   SDL_FlipRectV&#40;TempSurface, nil&#41;; // so the texture isn't upside down
   Surface &#58;= SDL_CreateRGBSurface&#40;SDL_SWSURFACE, Width, Height, TempSurface.format.BitsPerPixel,
     TempSurface.format.RMask,TempSurface.format.GMask,TempSurface.format.BMask,TempSurface.format.AMask&#41;;
   SDL_BlitSurface&#40;TempSurface, nil, Surface, nil&#41;;
   SDL_FreeSurface&#40;TempSurface&#41;;
  glEnable&#40;GL_TEXTURE_2D&#41;;
  glGenTextures&#40;1, @FTextureID&#41;;
  glBindTexture&#40;GL_TEXTURE_2D, FTextureID&#41;;
  glTexParameteri&#40;GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST&#41;;
  glTexParameteri&#40;GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST&#41;;
  glTexImage2D&#40;GL_TEXTURE_2D, 0, GL_RGBA, Width, Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, Surface.pixels&#41;;
 end;

I keep the surface around becuase I will probably update is everynow and then and refresh the texture.

Can any one see any obvious problems?

Dean