如何在mac中使用纹理.jpg图像作为openGL背景窗口？

Question

我想为mac设置一个openGL窗口的背景。背景将需要一个JPG或PNG文件。

这里是我的代码..

GLuint texture; //the array for our texture 

GLfloat angle = 0.0; 

GLuint LoadTexture (const char * filename, int width, int height){ 

// GLuint texture; 
unsigned char * data; 
FILE * file; 

//The following code will read in our RAW file 
file = fopen(filename, "rb"); 
if (file == NULL) return 0; 
data = (unsigned char *)malloc(width * height * 3); 
fread(data, width * height * 3, 1, file); 
fclose(file); 

glGenTextures(1, &texture); 
glBindTexture(GL_TEXTURE_2D, texture); 
glPixelStorei(GL_UNPACK_ALIGNMENT, 1); 
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); 

// // when texture area is small, bilinear filter the closest mipmap 
// glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, 
//     GL_LINEAR_MIPMAP_NEAREST); 
// // when texture area is large, bilinear filter the original 
// glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 
//  
// // the texture wraps over at the edges (repeat) 
// glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); 
// glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); 
//  
// //Generate the texture 
// glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 2, 2, 0,GL_RGB, GL_UNSIGNED_BYTE, data); 



// select modulate to mix texture with color for shading 
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); 

// when texture area is small, bilinear filter the closest mipmap 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, 
       GL_LINEAR_MIPMAP_NEAREST); 
// when texture area is large, bilinear filter the first mipmap 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 

// // the texture wraps over at the edges (repeat) 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); 
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); 

// build our texture mipmaps 
gluBuild2DMipmaps(GL_TEXTURE_2D, 3, width, height, 
        GL_RGB, GL_UNSIGNED_BYTE, data); 

free(data); 

return texture; //return whether it was successful 

} 

void FreeTexture(GLuint texture){ 
glDeleteTextures(1, &texture); 
} 

void cube() { 
glEnable(GL_TEXTURE_2D); 
glBindTexture(GL_TEXTURE_2D, texture); //bind the texture 

glPushMatrix(); 
glRotatef(angle, 0.0f, 0.0f, 1.0f); 
glBegin(GL_QUADS); 
glTexCoord2d(0.0,0.0); glVertex2d(-1.0,-1.0); 
glTexCoord2d(1.0,0.0); glVertex2d(+1.0,-1.0); 
glTexCoord2d(1.0,1.0); glVertex2d(+1.0,+1.0); 
glTexCoord2d(0.0,1.0); glVertex2d(-1.0,+1.0); 
glEnd(); 
glPopMatrix(); 
glutSwapBuffers(); 
//glutSolidCube(2); 
} 

void display() { 
    glClearColor (0.0,0.0,0.0,1.0); 
    glClear (GL_COLOR_BUFFER_BIT); 
    glLoadIdentity(); 
    gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); 
    texture = LoadTexture("/Users/macbook/MatrixEngineClientSample/Fighters/Sunset03.jpg", 256, 256 ); //load the texture 
    glEnable(GL_TEXTURE_2D); //enable 2D texturing 
// glEnable(GL_TEXTURE_GEN_S); //enable texture coordinate generation 
// glEnable(GL_TEXTURE_GEN_T); 
    cube(); 
    FreeTexture(texture); 
    //glutSwapBuffers(); 
    //angle ++; 
} 

void reshape (int w, int h) { 
    glViewport (0, 0, (GLsizei)w, (GLsizei)h); 
    glMatrixMode (GL_PROJECTION); 
    //glLoadIdentity(); 
    gluPerspective (50, (GLfloat)w/(GLfloat)h, 1.0, 100.0); 
    glMatrixMode (GL_MODELVIEW); 
} 

int main (int argc, char **argv) { 
    glutInit (&argc, argv); 
    glutInitDisplayMode (GLUT_DOUBLE); 
    glutInitWindowSize (500, 500); 
    glutInitWindowPosition (100, 100); 
    glutCreateWindow ("A basic OpenGL Window"); 
    glutDisplayFunc (display); 
    glutIdleFunc (display); 
    glutReshapeFunc (reshape); 
    glutMainLoop(); 
    return 0; 
} 

编辑

我希望看到这个图像作为OpenGL窗口的背景...图像低于..

但它显示此...

Answer 1

我咨询this Apple guide。

问题是文件被压缩并且有一个头文件，并且您的代码甚至使用文件头的一部分作为图像源。

我将这段代码：

// GLuint texture; 
unsigned char * data; 
FILE * file; 

//The following code will read in our RAW file 
file = fopen(filename, "rb"); 
if (file == NULL) return 0; 
data = (unsigned char *)malloc(width * height * 3); 
fread(data, width * height * 3, 1, file); 
fclose(file); 

更多的东西与此类似：

CFURLRef urlRef = (CFURLRef)[NSURL fileURLWithPath:@"/Users/macbook/MatrixEngineClientSample/Fighters/Sunset03.jpg"]; 
CGImageSourceRef myImageSourceRef = CGImageSourceCreateWithURL(url, NULL); 
CGImageRef myImageRef = CGImageSourceCreateImageAtIndex(myImageSourceRef, 0, NULL); 
CFDataRef data = CGDataProviderCopyData(CGImageGetDataProvider(myImageRef)); 
unsigned char *data = CFDataGetBytePtr(data); 

您可能需要核芯显卡和Core Foundation的添加到您的链接框架的名单。

Answer 2

PNG和JPG图像（与大多数其他图像格式一样）需要某种形式的解压缩/解码，因此从文件加载原始文件不会产生预期结果。它应该在读取文件头之后使用bmp或未压缩的tga图像：/。无论如何，这里有一些图像加载库，应该使加载图片轻松：

SOIL

DevIL

FreeImage

GLI