Q:

Difference in Processing 3D Animated Graphics Shader & Same 3D animated GIF

When we develop (HLSL Language) any 3D animation using Graphics shader (may be with help of DirectX) I know the shader get compiled to Shader bytecode. These byte codes implies some intermediate shader assembly instructions. These instruction will get passed to GPU driver and the GPU driver will convert those instructions to their proprietary GPU instructions and finally GPU will render them.
Now I would like to know when we see the exact same animation in a 3D GIF (some.gif) file, how does the Operating system render the 3D animation? 
Does it follow the same path to render the graphics or something different happens in case of a GIF?
Thanks,

A:

When rendering in DirectX, you eventually are converting your 3D scene into a 2D image to be displayed on your display device (eg. a monitor). This is generally done by using a projection matrix, which converts 3D coordinates into screen-space (2D) coordinates. 
Usually, the operating system doesn't display image files (.gifs) directly, they are loaded an rendered through another program (which may be distributed as part of the OS, for example, the thumbnail generation in Windows Explorer). How exactly the image is displayed is dependent on the implementation of the displaying program. There are many possibilities on how it could be implemented, DirectX, OpenGL, GDI, are all possibilities.

