SDL & OpenGL Texture Transparency
The code I use looks pretty much exactly like the code I posted earlier, minus the SDL_SetColorKey() call.
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Ok... I've been trying like crazy to get this working - nothing has worked!
I attempted using colorkeying - I used it before AND after copying the surface to the new surface before returning the GL texture.
I have also attempting using a TGA texture - this, instead of displaying with an alpha value, displays nothing at all! - it displays a pure white box...
can anyone, perhaps, take a look at the actual function I posted above and help me find where, in my code that I should place colorkeying functions or such of that sort?
Thanks for any more help..
I attempted using colorkeying - I used it before AND after copying the surface to the new surface before returning the GL texture.
I have also attempting using a TGA texture - this, instead of displaying with an alpha value, displays nothing at all! - it displays a pure white box...
can anyone, perhaps, take a look at the actual function I posted above and help me find where, in my code that I should place colorkeying functions or such of that sort?
Thanks for any more help..
This is the code from my engine, which loads textures in a format supported by the SDL_image library.
...and the GetPixel() function used...
Hopefully the code is straightforward.
Best regards,
SDL_Surface* lpTexture = IMG_Load(szFilename); if (!lpTexture) { // some error return; } m_iTextureWidth = lpTexture->w; m_iTextureHeight = lpTexture->h; glGenTextures(1, &m_iglTexture); rval = glGetError(); if (rval != GL_NO_ERROR) { if (lpTexture) { SDL_FreeSurface(lpTexture); lpTexture = NULL; } // some error return; } glBindTexture(GL_TEXTURE_2D, m_iglTexture); rval = glGetError(); if (rval != GL_NO_ERROR) { if (lpTexture) { SDL_FreeSurface(lpTexture); lpTexture = NULL; } // some error return; } int byte = 0; int w = lpTexture->w, h = lpTexture->h; int iTotalBytes = w * h * 4; unsigned char* lpNewTexture = new unsigned char[iTotalBytes]; if (!lpNewTexture) { if (lpTexture) { SDL_FreeSurface(lpTexture); lpTexture = NULL; } // some error return; } for (int y = 0; y < h; y++) { for (int x = 0; x < w; x++) { Uint8 r,g,b,a; Uint32 color = GetPixel(lpTexture, x, y); if(!bUseColorKey) { SDL_GetRGB(color, lpTexture->format, &r, &g, &b); a = 0xff; } else { SDL_GetRGBA(color, lpTexture->format, &r, &g, &b, &a); if ((r == iColorKeyRed) && (g == iColorKeyGreen) && (b == iColorKeyBlue)) { a = 0x00; } else { a = 0xff; } } lpNewTexture[byte++] = r; lpNewTexture[byte++] = g; lpNewTexture[byte++] = b; lpNewTexture[byte++] = a; } } ...and the GetPixel() function used...
Uint32 GetPixel(SDL_Surface *Surface, Sint32 X, Sint32 Y){ Uint8 *bits; Uint32 Bpp; if (X<0) puts("x too small in GetPixel!"); if (X>=Surface->w) puts("x too big in GetPixel!"); Bpp = Surface->format->BytesPerPixel; bits = ((Uint8 *)Surface->pixels)+Y*Surface->pitch+X*Bpp; // Get the pixel switch(Bpp) { case 1: return *((Uint8 *)Surface->pixels + Y * Surface->pitch + X); break; case 2: return *((Uint16 *)Surface->pixels + Y * Surface->pitch/2 + X); break; case 3: { // Format/endian independent Uint8 r, g, b; r = *((bits)+Surface->format->Rshift/8); g = *((bits)+Surface->format->Gshift/8); b = *((bits)+Surface->format->Bshift/8); return SDL_MapRGB(Surface->format, r, g, b); } break; case 4: return *((Uint32 *)Surface->pixels + Y * Surface->pitch/4 + X); break; } return -1;}Hopefully the code is straightforward.
Best regards,
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