private void renderNetz(){
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glBegin(GL_LINES);
        for (int j= -100; j < 100; j++){
            for(int i = -100; i < 100; i++) {
                if(i % 5 == 0) {
                    glColor3f(1,0,0);
                }
                else {
                    glColor3f(0, 0, 0);
                }
                glVertex3f(i,j,-100);
                glVertex3f(i,j,+100);
            }

            for(int i = -100; i < 100; i++) {
                if(i % 5 == 0) {
                    glColor3f(0,0,1);
                }
                else {
                    glColor3f(0, 0, 0);
                }
                glVertex3f(i,-100,j);
                glVertex3f(i,+100,j);
            }
        }
        glEnd();
    }