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View Full Version : help! what's the simplest way to generate an XY plot using openGL/glut?



Jefft
12-14-2005, 06:25 AM
given a set of x,y coordinates, what is the simplest way to plot the data? I want to be able to just plot the points and then I want to be able to draw a curve through the points. Thanks

songho
12-14-2005, 08:31 AM
Jefft,
To plot 2d points you may use glVertex2i(x,y).


glBegin(GL_POINTS);
glVertex2i(x, y);
glEnd();Drawing points very simple like above code, but you are not asking this, do you?

Jefft
12-14-2005, 08:57 AM
OK... next question... When I create a window, the origin (0,0) is at the center. All points I need to plot will be in the first quadrant (positive x, positive y). Is there a way to shift the view or something to only show the first quadrant?

Bob
12-14-2005, 09:02 AM
Look up glOrtho. It creates a projection matrix and you can use it map any part of the coordinate system to your window.

songho
12-14-2005, 09:35 AM
If the resolution of your rendering window is 400x300, set your projection matrix with:
gluOrtho2D(0, 400, 0, 300);

This gives you Quadrant 1 only. The origin (0,0) is the lower-left corner and (399,299) would be the top-right corner.
==song==