奇的OpenGL紋理問題？：

Question

這裏是我嘗試加載質地：

這是當我運行我的代碼我所看到的：

這裏是我正在使用的代碼：

#include "sdl.h" 
#include "sdl_opengl.h" 
#include <stdio.h> 
#include <gl/GL.h> 
#include <gl/GLU.h> 

Uint32 loadTexture(char* fileName) 
{ 
    Uint32 id; 
    SDL_Surface *img = NULL; 

    //load into memory using SDL 
    img = SDL_LoadBMP(fileName); 
    //generate an id for this texture 
    glGenTextures(1, &id); 
    //use this texture 
    glBindTexture(GL_TEXTURE_2D, id); 
    //load the texture into video memory via OpenGL 
    glTexImage2D(
     GL_TEXTURE_2D, 
     0, 
     GL_RGB, 
     img->w, 
     img->h, 
     0, 
     GL_RGB, 
     GL_UNSIGNED_SHORT_5_6_5, 
     img->pixels 
     ); 

    //set mip map settings 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 

    SDL_FreeSurface(img); 

    return id; 
} 

Uint32 tex; 

void init() 
{ 
    glClearColor(0.0, 0.0, 0.0, 1.0); 
    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    glOrtho(0.0, 1.0, 1.0, 0.0, -1.0, 1.0); 
    glMatrixMode(GL_MODELVIEW); 
    glEnable(GL_TEXTURE_2D); 

    tex = loadTexture("fireball.bmp"); 
} 
void display() 
{ 
    glClear(GL_COLOR_BUFFER_BIT); 
    glLoadIdentity(); 

    glBindTexture(GL_TEXTURE_2D, tex); 

    glBegin(GL_QUADS); 
    glTexCoord2f(0.0, 0.0); 
    glVertex3f(0.25, 0.25, 0.0); 


    glTexCoord2f(1.0, 0.0); 
    glVertex3f(0.5, 0.25, 0.0); 


    glTexCoord2f(1.0, 1.0); 
    glVertex3f(0.5, 0.5, 0.0); 


    glTexCoord2f(0.0, 1.0); 
    glVertex3f(0.25, 0.5, 0.0); 
    glEnd(); 
} 

int main() 
{ 
    INT32 isRunning = 1; 
    SDL_Surface *screen = NULL; 
    SDL_Event event; 
    INT32 start; 
    INT32 FPS = 30; 

    SDL_Init(SDL_INIT_EVERYTHING); 

    screen = SDL_SetVideoMode(640, 480, 32, SDL_OPENGL); 

    init(); 

    while(isRunning) 
    { 
     start = SDL_GetTicks(); 

     while(SDL_PollEvent(&event)) 
     { 
      switch(event.type) 
      { 
       case SDL_QUIT: isRunning = 0; break; 
      } 
     } 

     display(); 

     SDL_GL_SwapBuffers(); 

     if(1000/FPS > SDL_GetTicks() - start) 
     { 
      SDL_Delay(1000/FPS - (SDL_GetTicks() - start)); 
     } 
    } 

    SDL_Quit(); 

    return(0); 
} 

Answer 1

glTexImage2D(
    GL_TEXTURE_2D, 
    0, 
    GL_RGB, 
    img->w, 
    img->h, 
    0, 
    GL_RGB, 
    GL_UNSIGNED_SHORT_5_6_5, 
    img->pixels 
    ); 

這實際上是它的格式嗎？每2個字節是一個5/6/5 RGB像素。我並不知道Windows BMP文件可以存儲5/6/5圖像數據，但我從來沒有打算寫圖像加載代碼，所以我不確定。我認爲BMP數據只能是8/8/8 BGR格式。

那麼，即使它可以是5/6/5，你確定這個圖像是這種格式嗎？

另外，什麼是行對齊？我沒有看到您使用glPixelStorei設置GL_UNPACK_ALIGNMENT，所以您必須期望每行的大小都對齊到4個字節。這是真的？