Google cardBoard Android API (十五)：两个接口中的CardboardView.Renderer

CardboardView.Renderer

public static interface CardboardView.Renderer

Interface for renderers who need to handle all the stereo rendering details by themselves.

Public Methods

abstract void	onDrawFrame(HeadTransform headTransform, Eye leftEye, Eye rightEye)
abstract void	onFinishFrame(Viewport viewport)
abstract void	onRendererShutdown()
abstract void	onSurfaceChanged(int width, int height)
abstract void	onSurfaceCreated(EGLConfig config)

Public Methods

public abstract void onDrawFrame (HeadTransform headTransform, Eye leftEye, EyerightEye)

Requests to draw a new frame.

The implementor is assumed to handle all stereoscopic details by itself by making use of the provided head transformation and eye parameters.

If distortion correction is enabled the GL context will be set to draw into a framebuffer backed by a texture at the time of this call. If an implementor needs to change the current framebuffer, it must be reset back afterwards to the one obtained via

glGetIntegerv(GL_FRAMEBUFFER_BINDING,
...)

at the beginning of this call.

If VR mode is disabled, instead of providing the parameters of two eyes, the left eye will contain monocular rendering parameters and the right eye will be null. No distortion correction will take place in that case. For monocular rendering, the implementor
should feel free to ignore the FieldOfView and instead create a perspective matrix with whatever field of view is desired for monocular rendering (ScreenParams.getWidth()/ScreenParams.getHeight() can provide the aspect ratio). See the

setVRModeEnabled

method
for details.


Parameters

headTransform	The head transformation for this frame, independent to any eyes.
leftEye	Parameters of the left eye, or a single eye if VR mode is disabled.
rightEye	Parameters of the right eye, or null if VR mode is disabled.

public abstract void onFinishFrame (Viewport viewport)

Called before a frame is finished.

By the time of this call, the frame contents have been already drawn and, if enabled, distortion correction has been applied.

This method allows to perform additional overlay rendering over the frame results. For example, it could be used to draw markers that help users to properly center their device screens in their Cardboards.

A viewport object describing the bounds of the full surface is provided, but not set in the GL context.

Renderer

implementors
are responsible of setting the viewport if needed.


Parameters

viewport	Viewport of the full GL surface. To be set by renderers if needed.

public abstract void onRendererShutdown ()

Called on the renderer thread when the thread is shutting down.

Allows releasing GL resources and performing shutdown operations in the renderer thread. Called only if there was a previous call to

onSurfaceCreated

.

public abstract void onSurfaceChanged (int width, int height)

Called when there is a change in the surface dimensions.

Viewport, field of view and projection details are automatically updated.

Note that the eye parameters passed to

onDrawFrame(HeadTransform,
Eye, Eye)

are computed under the assumption that the surface dimensions correspond to a fullscreen landscape view. Any other configuration is likely to lead to convergence problems.


Parameters

width	New width of the surface in pixels.
height	New height of the surface in pixels.

public abstract void onSurfaceCreated (EGLConfig config)

Called when the surface is created or recreated.


Parameters

config	The EGL configuration used when creating the surface.