OpenGL纹理形式SDLSurface太暗了

Question

我遇到的问题与OpenGl goes too dark完全相同，但答案对我不起作用。我试图通过转换为纹理的表面来显示图像，结果太暗了：

原件：

在openGL之后

左边是原版，右边是OpenGl img。

这是我的代码：

void TexturedRect::draw(int scroll){

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    glBindTexture(GL_TEXTURE_2D, _texture);

    glEnable(GL_TEXTURE_2D);
    glBegin(GL_QUADS);  //Begining the cube's drawing

    int x = this->getX();
    int y = this->getY();
    int w = this->getWidth();
    int h = this->getHeight();
    int z = this->getZ();

    /*
    (0,0) ------ (1,0)
      |            |
      |            |
    (0,1) ------ (1,1)
    */
    glTexCoord3i(0, 0, 1);glVertex3i(x + scroll,         y,      z);
    glTexCoord3i(_tv, 0, 1);glVertex3i(x + w * _tv + scroll,     y,      z);
    glTexCoord3i(_tv, _tu, 1);glVertex3i(x + w * _tv + scroll,     y + h * _tu,  z);
    glTexCoord3i(0, _tu, 1);glVertex3i(x + scroll,         y + h * _tu,  z);

    glEnd();
    glDisable(GL_TEXTURE_2D);
}

void TexturedRect::createTextureFromSurface()
{
    SDL_Surface * surface = IMG_Load(filename.toStdString().c_str());
    // get the number of channels in the SDL surface
    GLint  nbOfColors = surface->format->BytesPerPixel;
    GLenum textureFormat = 0;

    switch (nbOfColors) {
    case 1:
        textureFormat = GL_ALPHA;
        break;
    case 3:     // no alpha channel
        if (surface->format->Rmask == 0x000000ff)
            textureFormat = GL_RGB;
        else
            textureFormat = GL_BGR;
        break;
    case 4:     // contains an alpha channel
        if (surface->format->Rmask == 0x000000ff)
            textureFormat = GL_RGBA;
        else
            textureFormat = GL_BGRA;
        break;
    default:
        qDebug() << "Warning: the image is not truecolor...";
        break;
    }

    glEnable( GL_TEXTURE_2D );
    // Have OpenGL generate a texture object handle for us
    glGenTextures( 1, &_texture );

    // Bind the texture object
    glBindTexture( GL_TEXTURE_2D, _texture );


    // Edit the texture object's image data using the information SDL_Surface gives us
    glTexImage2D( GL_TEXTURE_2D, 0, nbOfColors, surface->w, surface->h, 0,
                  textureFormat, GL_UNSIGNED_BYTE, surface->pixels );

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

}

Answer 1

您可能在代码中的其他位置设置了一些状态，当您希望它禁用它来绘制此四边形时仍然启用。

尝试在glBindTexture（GL_TEXTURE_2D，_texture）之后添加以下内容;在你的绘图代码中（重要的是它在draw方法中完成而不是createTextureFromSurface方法）：

glDisable(GL_BLEND);
glDisable(GL_LIGHTING);
glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE )
glColor3f(1.0f, 1.0f, 1.0f);

如果这样可行，您可以逐个注释掉它们，以确定导致问题的状态。在绘制需要它的对象时，任何禁用绘制此四边形的状态都需要重新启用。