我正在尝试加载并显示一个带有透明度的.png图像。整个图像不是透明的，它只是我在Photoshop中裁剪的一个包的图片，并且周围有透明度。我需要将其加载到使用SDL和OpenGL的C++程序中，但是当我尝试时，它没有正确地显示，图像周围的空间“模糊”（我只能这样说）。我的意思是，透明度不起作用。
这是我目前的代码：
init()方法：
drawScene() 方法：
该方法用于绘制场景。
这是我目前的代码：
init()方法：
SDL_Surface *surface;
GLenum texture_format;
GLint nOfColors;
if ( (surface = IMG_Load("bag.png")) ) {
// Check that the image's width is a power of 2
if ( (surface->w & (surface->w - 1)) != 0 ) {
printf("warning: bag.png's width is not a power of 2\n");
}
// Also check if the height is a power of 2
if ( (surface->h & (surface->h - 1)) != 0 ) {
printf("warning: bag.png's height is not a power of 2\n");
}
// get the number of channels in the SDL surface
nOfColors = surface->format->BytesPerPixel;
if (nOfColors == 4) // contains an alpha channel
{
if (surface->format->Rmask == 0x000000ff)
texture_format = GL_RGBA;
//else
//texture_format = GL_BGRA;
} else if (nOfColors == 3) // no alpha channel
{
if (surface->format->Rmask == 0x000000ff)
texture_format = GL_RGB;
//else
//texture_format = GL_BGR;
} else {
printf("warning: the image is not truecolor.. this will probably break\n");
// this error should not go unhandled
}
// Have OpenGL generate a texture object handle for us
glGenTextures( 1, &texture );
// Bind the texture object
glBindTexture( GL_TEXTURE_2D, texture );
// Set the texture's stretching properties
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
// Edit the texture object's image data using the information SDL_Surface gives us
glTexImage2D( GL_TEXTURE_2D, 0, nOfColors, surface->w, surface->h, 0,
texture_format, GL_UNSIGNED_BYTE, surface->pixels );
}
else {
printf("SDL could not load bag.png: %s\n", SDL_GetError());
SDL_Quit();
//return 1;
}
// Free the SDL_Surface only if it was successfully created
if ( surface ) {
SDL_FreeSurface( surface );
}
drawScene() 方法：
该方法用于绘制场景。
float xMin, xMax, yMin, yMax;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0f, 0.0f, -6.0f);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // Use nice (linear) scaling
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); // Use nice (linear) scaling
glBegin (GL_QUADS);
glNormal3f(0.0f, 0.0f, 1.0f);
if (texturesOn) glTexCoord2f(0.0f, 1.0f);
glVertex3f(4.3f, -3.5f, 0.0f); //bottom left
if (texturesOn) glTexCoord2f(1.0f, 1.0f);
glVertex3f(5.3f, -3.5f, 0.0f); //bottom right
if (texturesOn) glTexCoord2f(1.0f, 0.0f);
glVertex3f(5.3f, -4.5f, 0.0f); //top right
if (texturesOn) glTexCoord2f(0.0f, 0.0f);
glVertex3f(4.3f, -4.5f, 0.0f); //top left
glEnd();
glDisable(GL_TEXTURE_2D);
glutSwapBuffers();