Cocos3D - Take various screenshots in the background

Question

Using Cocos3D, is it possible to take screenshot of the 3D model in the background without the user knowing it?

For pre-processing purpose and other usage, I want to take screenshots of the 3D model at various angles. Following the Render-To-Texture capability, I noticed when my scene is not visible, the drawSceneContentWithVisitor: method only execute once rather than at every rendering cycle. For obvious reason, the CC3GLFramebuffer* won't get updated with new data, hence, I'm only able to take the initial screenshot.

Thanks.

Answer 1

In Cocos3D, you can render your 3D scene to an off-screen surface. See the CC3DemoMashUp addTelevision and drawSceneContentWithVisitor: methods for an example of how to do this.

What is important is that the 3D drawing environment has been established when you perform your drawing. The safest place to do this is inside your drawSceneContentWithVisitor: method. But if you want to render somewhere else, you need to invoke the CC3Scene open3DWithVisitor: and CC3Scene close3DWithVisitor: methods before and after rendering. See the implementations of the CC3Scene processInitializeScene and open methods for examples of how to do that.

To render your scene from multiple viewpoints, you need to add multiple cameras to your scene, and set the camera property of your drawing visitor appropriately to select a camera before rendering. See how this is done in the CC3DemoMashUpScene addTelevision and drawToTVScreen methods. The drawToTVScreen method also shows how to handle clearing the color and depth buffers of your surface.