[OpenGL] Render using buffer.
Author
Is there any method that I save current frame buffer and
render the buffer instead of full 3D scene in OpenGL.
Because my scene do not change and it do not need any update,
so I think if I can save my current frame buffer, and render using
the buffer by just 2D rendering, performance will rise up dramatically.
But, I didn't find the way.
I read some function's decriptions, glCopyPixels(), glDrawPixels().
Unfortunately I didn't catch how can I make it using that functions.
Any comments please...
GLint index;
glGenTextures (1, &index);
glBindTexture (GL_TEXTURE_2D, index);
glCopyTexImage2D (GL_TEXTURE_2D, 0, GL_RGB, 0, 0, winW, winH, 0);
Now index is a texture that contains your scene (provided that the scene is a power-of-two thing, otherwise you'll have to mess around a bit to do it).
But, if your scene isn't changing, why re-display it? Only re-render when something has changed in your scene. :)
glGenTextures (1, &index);
glBindTexture (GL_TEXTURE_2D, index);
glCopyTexImage2D (GL_TEXTURE_2D, 0, GL_RGB, 0, 0, winW, winH, 0);
Now index is a texture that contains your scene (provided that the scene is a power-of-two thing, otherwise you'll have to mess around a bit to do it).
But, if your scene isn't changing, why re-display it? Only re-render when something has changed in your scene. :)
glGenRenderbuffersEXT can be used to create a specialized offscreen render buffer. I use this for the same purpose you do.
Here is a list of the related functions:
glBindFramebufferEXT;
glDeleteFramebuffersEXT;
glGenFramebuffersEXT;
glFramebufferTexture2DEXT;
glBindRenderbufferEXT;
glDeleteRenderbuffersEXT;
glGenRenderbuffersEXT;
glRenderbufferStorageEXT;
glFramebufferRenderbufferEXT;
The reason to redisplay the 2D buffer is so that any areas of the screen which may have been drawn over by the OS can be refreshed in a non-OS-specific way.
Here is a list of the related functions:
glBindFramebufferEXT;
glDeleteFramebuffersEXT;
glGenFramebuffersEXT;
glFramebufferTexture2DEXT;
glBindRenderbufferEXT;
glDeleteRenderbuffersEXT;
glGenRenderbuffersEXT;
glRenderbufferStorageEXT;
glFramebufferRenderbufferEXT;
The reason to redisplay the 2D buffer is so that any areas of the screen which may have been drawn over by the OS can be refreshed in a non-OS-specific way.
If you have a relatively-recent video card, the shiny new solution these days is to use the EXT_framebuffer_object extenstion.
This extension allows you to render the scene directly to a texture without needing any of the glCopy* functions.
This extension allows you to render the scene directly to a texture without needing any of the glCopy* functions.
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