Dear All,

i just started to learn OGL. and try to understand it.

and try to draw line. but it does not draw in negative value

my Setting is

Code :
	int nCx = rect.Width();
	int nCy = rect.Height();
	double fAspect = (double)nCy / (double)nCx;
 
	// setup orthographic projection
	glMatrixMode(GL_PROJECTION);
 
	glLoadIdentity();
 
	if(nCx >= nCy) {
		glOrtho(0, m_dDocSize, 0, m_dDocSize * fAspect, -m_dDocSize, m_dDocSize);
	}
	else {
		glOrtho(0, m_dDocSize / fAspect, 0, m_dDocSize, -m_dDocSize, m_dDocSize);
	} 
	//glViewport(-1, -1, nCx + 2, nCy + 2);
 
	glViewport(nCx/2,nCy/2,nCx,nCy); // x = y = 0 at the center of screen.


Code :
                glColor3f(1.0f, 0.0f, 1.0f);
		glBegin(GL_LINES);
 
		glVertex3d(-x, -y,0);
		glVertex3d(x, y,0);
		glEnd();


will some one help me how to draw line with negative value

thanks in advance.
Amrit