SDL，OpenGL的：分割故障

Question

當我嘗試生成使用OpenGL紋理我得到了這個方法分割故障：僅與NVIDIA驅動程序的debian

void RendererGL::create_gl(SDL_Surface * surf, GLuint * tex) { 
    GLenum format; GLint colors_amount = surf->format->BytesPerPixel; 

    if (colors_amount == 4) { 
      if (surf->format->Rmask == 0x000000ff) 
        format = GL_RGBA; 
      else 
        format = GL_BGRA; 
    } 
    else if (colors_amount == 3) { 
      if (surf->format->Rmask == 0x000000ff) 
        format = GL_RGB; 
      else 
        format = GL_BGR; 
    } 
    else { 
     gCritical("Image is not truecolor"); 
    } 
    glGenTextures(1, tex); 

    glBindTexture(GL_TEXTURE_2D, *tex); 

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); 

    glTexImage2D(GL_TEXTURE_2D, 0, colors_amount, surf->w, surf->h, 0, format, 
       GL_UNSIGNED_BYTE, surf->pixels); } 

I`ve這個問題。開源驅動應用程序運行正常。 Valgrind的測試回報：

[ Info ] RendererGL::Init GL 
==13033== Thread 3: 
==13033== Invalid read of size 8 
==13033== at 0x51293C9: ??? (in /usr/lib/x86_64-linux-gnu/nvidia/current/libGL.so.304.64) 
==13033== by 0x419B0F: RendererGL::initGL() (RendererGL.cpp:12) 
==13033== by 0x41036C: Renderer::Renderer() (Renderer.cpp:27) 
==13033== by 0x4058EA: Renderer::getInstance() (Renderer.hpp:17) 
==13033== by 0x40B648: StandardReferences::StandardReferences() (StandardReferences.hpp:13) 
==13033== by 0x414C26: Map::Map(short**, unsigned short, unsigned int, unsigned int) (Map.cpp:8) 
==13033== by 0x4136E4: MapManager::loadMapFromFile(std::string, short) (MapManager.cpp:82) 
==13033== by 0x4138A0: MapManager::load() (MapManager.cpp:97) 
==13033== by 0x4084BA: Resource::load() (Resource.cpp:36) 
==13033== by 0x4196AF: Splash::initThread(void*) (Splash.cpp:99) 
==13033== by 0x53D0405: ??? (in /usr/lib/x86_64-linux-gnu/libSDL-1.2.so.0.11.4) 
==13033== by 0x5413898: ??? (in /usr/lib/x86_64-linux-gnu/libSDL-1.2.so.0.11.4) 
==13033== Address 0x658 is not stack'd, malloc'd or (recently) free'd 
==13033== 
==13033== 
==13033== HEAP SUMMARY: 
==13033==  in use at exit: 22,104,451 bytes in 31,729 blocks 
==13033== total heap usage: 47,499 allocs, 15,770 frees, 54,869,707 bytes allocated 
==13033== 
==13033== LEAK SUMMARY: 
==13033== definitely lost: 833 bytes in 8 blocks 
==13033== indirectly lost: 1,728 bytes in 38 blocks 
==13033==  possibly lost: 269,732 bytes in 99 blocks 
==13033== still reachable: 21,832,158 bytes in 31,584 blocks 
==13033==   suppressed: 0 bytes in 0 blocks 
==13033== Rerun with --leak-check=full to see details of leaked memory 
==13033== 
==13033== For counts of detected and suppressed errors, rerun with: -v 
==13033== Use --track-origins=yes to see where uninitialised values come from 
==13033== ERROR SUMMARY: 12 errors from 2 contexts (suppressed: 6 from 6) 

Answer 1

我bettin'這是與RGB表面而不是那些RGBA段錯誤。

嘗試撥打glTexImage2D()之前glPixelStorei(GL_UNPACK_ALIGNMENT, 1)​。

GL_UNPACK_ALIGNMENT默認爲4，對於RGBA數據可以正常工作，但會導致OpenGL讀取RGB表面的surf->pixels的末尾。

如果surf->pitch非零，則必須使用GL_UNPACK_ROW_LENGTH​。