[QtOpenGL] gl_blend vs MultiSampled

[muby]

[QtOpenGL] gl_blend vs MultiSampled
Hi,

I'm new in OpenGL and I made some tests with Qt example about "Aliasing".

I would like to be sure about my results.

It's seem the result of "Anti-aliasing" to be more beautiful with the "gl_blend" method

Graphic card : ATI Mobility Radeon HD 4650

my results :



I test the different settings of the drivers ATI :

• wide-tent
• box
• narrow-tent
• edge-detect

with differents samples (setSample(2/4/8))

for me the best "Anti-aliasing" is without multisampled.

Here the code for my test.

int main(int argc, char *argv[])
{
	QApplication a(argc, argv);
	QGLFormat format = QGLFormat::defaultFormat();
	format.setSampleBuffers(false);
	//format.setSamples(2);
	//format.setSamples(4);
	format.setSamples(8);
	MyGlWindow*_glwindow= new MyGlWindow(format);
	_glwindow->show();
	return a.exec();
}

int main(int argc, char *argv[])
{
	QApplication a(argc, argv);
	QGLFormat format = QGLFormat::defaultFormat();
	format.setSampleBuffers(false);
	//format.setSamples(2);
	//format.setSamples(4);
	format.setSamples(8);
	MyGlWindow*_glwindow= new MyGlWindow(format);
	_glwindow->show();
	return a.exec();
}

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void MyGlWindow::initializeGL()
{
	if(format().sampleBuffers())
	{
		glEnable(GL_MULTISAMPLE);
	}
	else
	{
		glEnable(GL_BLEND);
		glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
 
		glEnable (GL_LINE_SMOOTH);
		glEnable (GL_POINT_SMOOTH);
		glEnable (GL_POLYGON_SMOOTH);
		glHint (GL_LINE_SMOOTH_HINT, GL_DONT_CARE);
		glHint (GL_POINT_SMOOTH_HINT, GL_DONT_CARE);
		glHint (GL_POLYGON_SMOOTH_HINT, GL_DONT_CARE);
	}
}

void MyGlWindow::initializeGL()
{
	if(format().sampleBuffers())
	{
		glEnable(GL_MULTISAMPLE);
	}
	else
	{
		glEnable(GL_BLEND);
		glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
		
		glEnable (GL_LINE_SMOOTH);
		glEnable (GL_POINT_SMOOTH);
		glEnable (GL_POLYGON_SMOOTH);
		glHint (GL_LINE_SMOOTH_HINT, GL_DONT_CARE);
		glHint (GL_POINT_SMOOTH_HINT, GL_DONT_CARE);
		glHint (GL_POLYGON_SMOOTH_HINT, GL_DONT_CARE);
	}
}

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To finish, is it normal that we can't get the same "anti-aliasing" result with "GL_MULTISAMPLE" ?


thx.