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Asked: 2026-05-11T10:34:37+00:00

Now that my OpenGL application is getting larger and more complex, I am noticing

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Now that my OpenGL application is getting larger and more complex, I am noticing that it’s also getting a little slow on very low-end systems such as Netbooks. In Java, I am able to get around this by drawing to a BufferedImage then drawing that to the screen and updating the cached render every one in a while. How would I go about doing this in OpenGL with C++?

I found a few guides but they seem to only work on newer hardware/specific Nvidia cards. Since the cached rendering operations will only be updated every once in a while, i can sacrifice speed for compatability.

glBegin(GL_QUADS);        setColor(DARK_BLUE);         glVertex2f(0, 0);                  //TL        glVertex2f(appWidth, 0);           //TR        setColor(LIGHT_BLUE);        glVertex2f(appWidth, appHeight);   //BR        glVertex2f(0, appHeight);          //BR glEnd();

This is something that I am especially concerned about. A gradient that takes up the entire screen is being re-drawn many times per second. How can I cache it to a texture then just draw that texture to increase performance?

Also, a trick I use in Java is to render it to a 1 X height texture then scale that to width x height to increase the performance and lower memory usage. Is there such a trick with openGL?

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1 Answer

  1. Hey there, thought I’d give you some insight in to this.

    There’s essentially two ways to do it.

    Frame Buffer Objects (FBOs) for more modern hardware, and the back buffer for a fall back.

    The article from one of the previous posters is a good article to follow on it, and there’s plent of tutorials on google for FBOs.

    In my 2d Engine (Phoenix), we decided we would go with just the back buffer method. Our class was fairly simple and you can view the header and source here:

    http://code.google.com/p/phoenixgl/source/browse/branches/0.3/libPhoenixGL/PhRenderTexture.h http://code.google.com/p/phoenixgl/source/browse/branches/0.3/libPhoenixGL/PhRenderTexture.cpp

    Hope that helps!

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