Qt 5.3 OpenGL - vertex buffer object drawing using the core profile
- by user3700881
Im using Qt 5.3 to create a QWindow to do some basic rendering stuff. The QWindow is declared like this:
class OpenGLWindow : public QWindow, protected QOpenGLFunctions_3_3_Core
{
Q_OBJECT
...
}
It is initialized in the constructor:
OpenGLWindow::OpenGLWindow(QWindow *parent) : QWindow(parent)
{
QSurfaceFormat format;
format.setVersion(3,3);
format.setProfile(QSurfaceFormat::CoreProfile);
this->setSurfaceType(OpenGLSurface);
this->setFormat(format);
this->create();
_context = new QOpenGLContext;
_context->setFormat(format);
_context->create();
_context->makeCurrent(this);
this->initializeOpenGLFunctions();
...
}
And that's the rendering code:
void OpenGLWindow::render()
{
if(!isExposed())
return;
_context->makeCurrent(this);
glClear(GL_COLOR_BUFFER_BIT);
glUseProgram(_shaderProgram);
glBindBuffer(GL_ARRAY_BUFFER, _positionBufferObject);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(0);
glUseProgram(0);
_context->swapBuffers(this);
}
I am trying to draw a simple triangle using a vertex and fragment shader. The problem is that the triangle is not showing up when the core profile is set. Only when I set the OpenGL version to 2.0 or when I use the compatibility profile, it shows up. From my point of view that doesn't make any sense because I am not using fixed functionality at all. What am I missing?
