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Amrit.shr
04-01-2015, 02:59 AM
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



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.







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