Hi,

I think I found critical bug.

I have simple inherited class called Texture

Texture.h
class Texture : public QOpenGLTexture
{
public:
Texture(const QImage& image, MipMapGeneration genMipMaps = GenerateMipMaps);
~Texture();

const QImage getImage();

private:
QOpenGLFunctions_4_2_Core* GLfuncs;
};

typedef QSharedPointer<Texture> TexturePtr;
Texture.cpp
Texture::Texture(const QImage& image, MipMapGeneration genMipMaps)
: QOpenGLTexture(image, genMipMaps)
{
QOpenGLContext* context = QOpenGLContext::currentContext();

Q_ASSERT(context);

GLfuncs = context->versionFunctions<QOpenGLFunctions_4_2_Core>();
GLfuncs->initializeOpenGLFunctions();
}

Texture::~Texture()
{
//destroy(); // don't crash, show warning in debug "Requires a valid current OpenGL context.
Texture has not been destroyed"
//QOpenGLTexture::~QOpenGLTexture(); // crash, show warning in debug like destroy
}

const QImage Texture::getImage()
{
int width, height;

bind();

GLfuncs->glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, &width);
GLfuncs->glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, &height);

if(width <= 0 || height <= 0)
return QImage();

GLint bytes = width * height * 4;

unsigned char* data = (unsigned char*)malloc(bytes);

GLfuncs->glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);

QImage img = QImage(data, width, height, QImage::Format_RGBA8888);

return img;
}

There is also my code where I loading texture into memory, if texture is already in TextureManager I’m trying to destroy it, and here become problem!

TextureManager.cpp
void TextureManager::loadTexture(QString textureName, QString texturePath)
{
QImage textureImage(texturePath);

TexturePtr texture(new Texture(textureImage.mirrored()));

QPair<QString, TexturePtr> pair;

foreach(pair, textures)
{
if(textureName == pair.first && texturePath == pair.second->getPath())

{ texture->destroy(); // point of crash return; }

}

textures.append(qMakePair<QString, TexturePtr>(textureName, texture));
}

Here you can visit part of destructor in QOpenGLTexture [qt.gitorious.org] to source code)
https://qt.gitorious.org/qt/qtbase/source/fc10bfd55035d27c9352c1678c3aad87c4be2e09:src/gui/opengl/qopengltexture.cpp#L131-244 line 181:
void QOpenGLTexturePrivate::destroy()
{
if (QOpenGLContext::currentContext() != context)

{ // WTF? this "context" using some QOpenGLTextureHelper which cant be possible in QOpenGLContext::currentContext so this will never be true! qWarning("Requires a valid current OpenGL context.\n" "Texture has not been destroyed"); return; }

texFuncs->glDeleteTextures(1, &textureId);
//...
}

I’m using QGLWidget, calling this->makeCurrent(), then initializing TextureManager, next line = textureManager->loadTexture(“Example”, “pathToTexture.png”);

I don’t know who wrote this class, so I can’t contact him and consulate if it is really bug or critical error or something like that.

Thanks.