glDeleteTextures, leaking?

Question

I found a rather disguting behaviour of glDeleteTexture, deleteing only parts of the aqcuired memory (GPU side and as Textures get saved back for the sake of speed in RAM), which in my case, is a showstopper bug, my program eating up all memory.

I don't want/require you to read all of the code, it's just a demo, I'd rather know how to actually use glDeleteTextures so it does not leak any memory.

The example code requires Qt 4.5 or later to compile:

glleak.pro

QT += opengl

SOURCES += main.cpp \
    glleak.cpp
HEADERS += glleak.h

main.cpp

#include <QtOpenGL>
#include <QtGui>
#include "glleak.h"

int main(int argc, char** argv){
    QApplication app(argc, argv);
    glleak gll(0);
    gll.show();
    return app.exec();
}

glleak.h

#ifndef GLLEAK_H
#define GLLEAK_H

#include <QGLWidget>
#include <QMouseEvent>
#include <QDebug>
#include <QList>

class glleak : public QGLWidget
{
    Q_OBJECT
public:
    glleak(QWidget* parent = 0);
    virtual ~glleak();
protected:
    void initializeGL();
    void paintGL();
    void resizeGL(int w, int h);
    void drawScene(GLenum mode);

    void wheelEvent(QWheelEvent* event);

    void hardcoreTexturing();
private:
    QList<GLuint> texels;

};

#endif // GLLEAK_H

glleak.cpp

glleak::glleak(QWidget* parent) :
        QGLWidget(parent)
{
}

glleak::~glleak()
{
}


void glleak::initializeGL(){
    glClearColor(0.0f,0.0f,0.0f,0.0f);
    glEnable(GL_TEXTURE_2D);
    glEnable(GL_MULTISAMPLE);
    glLineWidth (1.5f);
    glPointSize(4.5f);
    glEnable (GL_BLEND);
    glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}

void glleak::resizeGL(int w, int h){
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-w/2.0, w/2.0, h/2.0, -h/2.0, -1.0, 1.0);
    glMatrixMode(GL_MODELVIEW);
    glViewport(0, 0, w, h);
    glLoadIdentity();
}

void glleak::paintGL(){
    glPushMatrix();
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    glColor3f(1.0f,1.0f,1.0f);
    drawScene(GL_RENDER);
    glPopMatrix();
}




void glleak::drawScene(GLenum mode){
    qDebug() << "drawed #" << texels.count() << " Textures";
    hardcoreTexturing();
}


void glleak::hardcoreTexturing(){
    glEnable(GL_TEXTURE_2D);
    for ( int i(0); i<texels.count(); ++i){
        glPushMatrix();
        glTranslatef(1.1f*i, 2.2f*i, 0.0f);
        glBindTexture(GL_TEXTURE_2D, texels.at(i));
        glBegin(GL_QUADS);
        {
            glTexCoord2i(0,0);
            glVertex2i(-128,-128);

            glTexCoord2i(0,1);
            glVertex2i(-128,128);

            glTexCoord2i(1,1);
            glVertex2i(128,128);

            glTexCoord2i(1,0);
            glVertex2i(128,-128);

        }
        glEnd();
        glPopMatrix();
    }
    glDisable(GL_TEXTURE_2D);
}


void glleak::wheelEvent(QWheelEvent* event){
    glEnable(GL_TEXTURE_2D);
    int n(50);
    if (event->delta()>0){
        qDebug() << "gen textures";
        for (int i(0); i<n; ++i){
            QImage t("./ballmer_peak.png","png");
            GLuint tex(0);
            glGenTextures(1, &tex);
            glBindTexture(GL_TEXTURE_2D, tex);
            glTexImage2D( GL_TEXTURE_2D, 0, 3, t.width(), t.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, t.bits() );
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
            glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
            texels.append(tex);
        }
    }
    else{
        qDebug() << "del textures";
        for (QList<GLuint>::iterator i(texels.begin()); i!=texels.end();){
            glDeleteTextures(1, &(*i));
            i = texels.erase(i);
            if (--n <= 0)
                break;


        }
    }
    glDisable(GL_TEXTURE_2D);
        updateGL();
}

ballmer_peak.png A Image to load and render

Note: Compile demo: Just put it all in a folder, rename your image to ballmer_peak.png, call qmake, make, ./glleak Note: Demo usage: Use mousewheel to generate or delete 50 Textures at once

If I use glDeleteTextures completly wrong, please tell me how to use it. I am way out of ideas as my usage complies to the official OpenGL glDeleteTextures usage.

Answer 1

for (QList<GLuint>::iterator i(texels.begin()); i!=texels.end();)

switch to

for (QList<GLuint>::iterator i(texels.end()); i!=texels.begin();)