How to draw line in OpenGL?

c++, line, opengl

Solution

(.25, .25) and (.75,.75) are line's start and end point.

To draw a line from (10,10) to (20,20):

glBegin(GL_LINES);
    glVertex2f(10, 10);
    glVertex2f(20, 20);
glEnd();

Problem

I want to draw a line in OpenGL. ``` glBegin(GL_LINES); glVertex2f(.25,0.25); glVertex2f(.75,.75); glEnd(); ``` This code draws the line, but if I want to draw a line from coordinate (10,10) to coordinate (20,20) what should I do? What do (.25, .25) and (.75, .75) mean?

Original source