Message Board
| Message Board > C/C++ > OpenGL purple anti-aliased textures |
| June 1, 2008, 10:28 | |
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Htbaa
Perl 368 posts 
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Alright. For most images I get a purple border around them, which is currently delaying the release of screenshots or a demo of 2dsupershoot. When using SDL software rendering I'm not having this problem. But with OpenGL I do, and it's supposed to be in the part of converting the SDL_Surface to a texture. When converting a SDL_Surface to a texture I copy all pixels, including alpha value. If the image has alpha blended pixels (like the SDL_Surfaces from SDL_TTF) then that value is used. Otherwise, if the color is the same as the colorkey then it's being blended so the color won't be visible. This is my spritesheet.  I really have no idea why the purple border is there. I thought it had to do something with how glClear was setup but that doesn't matter at all. Any suggestions? ____________ blog.htbaa.com |
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| June 1, 2008, 11:11 | |
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(. )( .)
top pussy 447 posts 
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I'd say alpha blending isn't working. The problem could be the graphic files or the code. Quadruple check both? ____________ gay |
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| June 1, 2008, 11:15 | |
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Sandman
F3n!x0r 1194 posts 
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Could you paste the code for conversion? Did you enable blending and set an appropriate blend function? For example: C code: glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA); ____________ BennuWiki Yes, my avatar has grey borders in IE (so get a decent browser) ROOFLEZ ROOFLEZ |
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| June 1, 2008, 11:17 | |
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Htbaa
Perl 368 posts
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I just had a moment to think whilst under the shower, and this fixed my problem. C++ code: // Get pixeldata Uint32 pixel = get_pixel32(this->graphic, x, y); // Get R G and B from pixel Uint8 r,g,b,a; SDL_GetRGBA(pixel, this->graphic->format, &r, &g, &b, &a); // Set pixel to black transparent if the color is the // same as the colorkey if(pixel == this->graphic->format->colorkey) { r = g = b = a = 0x00; } // Otherwise use the provided alpha value else { a = static_cast<int>(a); } Before all I did was this: C++ code: a = (pixel == this->graphic->format->colorkey) ? 0 : static_cast<int>(a); The last part worked for SDL_TTF created SDL_Surfaces. It all works now. So I think later today some screenshots and perhaps a little demo! ____________ blog.htbaa.com |
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Message Board > C/C++ > OpenGL purple anti-aliased textures