Hello,
I’ve been trying to add some graphics to one of my apps, and for that I was using ofImage, writing pixel data, then drawing it as a texture with ofImage::draw() After initialization of the ofImage the data stored in the ofTexture seems correct, but when I write the pixels in a separate worker thread the data reverts to 0xcdcdcd on all pixels, which I interpreted (probably falsely) as uninitialized. Since the problem was reproducible, here I present you with the test app:
ofApp.h:
class ofApp : public ofBaseApp{
public:
void setup();
void draw();
GUI_Class* ui;
ThreadedClass* thread;
};
ofApp.cpp:
void ofApp::setup(){
thread = new ThreadedClass();
}
void ofApp::draw(){
thread->Draw();
}
GUI_Class.h:
class GUI_Class
{
public:
GUI_Class();
void SetPixels(int seed);
void Draw();
private:
ofImage* Image;
};
GUI_Class.cpp:
GUI_Class::GUI_Class()
{
ofPixels *p = new ofPixels();
p->allocate(640, 640, ofImageType::OF_IMAGE_COLOR);
Image = new ofImage(*p);
delete p;
}
void GUI_Class::SetPixels(int seed)
{
for (int y = 0; y < Image->getWidth(); y++)
{
for (int x = 0; x < Image->getHeight(); x++)
{
Image->setColor(x, y, ofColor((x + y + seed) % 255, (x - y - seed) % 255, (x * (y + seed)) % 255));
}
}
Image->update();
}
void GUI_Class::Draw()
{
Image->draw(0, 0, 640, 640);
}
ThreadedClass.h:
class ThreadedClass : public ofThread
{
public:
ThreadedClass();
void Draw();
private:
void threadedFunction() override;
GUI_Class* UI;
};
ThreadedClass.cpp:
ThreadedClass::ThreadedClass()
{
//ofTexture is CORRECT
UI = new GUI_Class();
//ofTexture is CORRECT
startThread();
}
void ThreadedClass::Draw()
{
lock();
UI->Draw();
unlock();
}
void ThreadedClass::threadedFunction()
{
//ofTexture is INCORRECT
int i = 0;
while (isThreadRunning())
{
lock();
//ofTexture is INCORRECT
UI->SetPixels(i);
//ofTexture is INCORRECT
i = (i + 1) % 640;
unlock();
ofSleepMillis(200);
}
}
The texture drawn on the window is homogenous light grey, probably 0xcdcdcd, which you can test by dumping the texture withImage->getTexture().readToPixels() at the lines marked with “INCORRECT”.
If you modify the ofApp.cpp to
void ofApp::setup(){
ui = new GUI_Class();
ui->SetPixels(100);
}
void ofApp::draw(){
ui->Draw();
}
everything works as intended. All through this the values in ofImage::pixels remains correct
Has anyone encountered this before, or has any idea/suggestion?