I am using OpenGL in C++ language and Visual Studio 2013 as my IDE
Consider the function sin(pi*x/pi)
ranging from x=-4 to +4
i have the following code
gluOrtho2D(-5.0, 5.0, -0.3, 1.0);
and
glBegin(GL_LINE_STRIP);
for (GLfloat x = -4.0; x<4.0; x += 0.1)
{
glVertex2f(x, sin(3.14159*x) / 3.15159);
}
glEnd();
glFlush();
it draws the function fine
Consider the following statement
gluOrtho2D(0.0, (GLdouble)screenWidth, 0.0, (GLdouble)screenHeight);
e.g
gluOrtho2D(0.0, 640.0, 0.0,480.0);
contrast it with
gluOrtho2D(-5.0, 5.0, -0.3, 1.0);
i do not understand at all the negative values used in Ortho2D
my question is how would i set values in glOrtho2D function so that the function is drawn in the entire 4 quadrants of a graph and origin is at the center of screen
and also how would i display the axes as well in the output … with X-cordinates and Y-coordinates also being marked on the screen ?