Use the multiframe rendering API

Use the multiframe rendering API to record frames that HDRP accumulates.

Limitations

The multi-frame rendering API internally changes the Time.timeScale of the Scene. This means that:

• You can't have different accumulation motion blur parameters per camera.

• Projects that already modify this parameter per frame aren't be compatible with this feature.

• The API internally reduces the value of the Time.fixedDeltaTime parameter, which controls the interval of physics computations. The smaller timestep makes the physics solver more accurate and stable. As a result, the physics behavior with the API may appear slightly different.

Multiframe rendering API calls

The multiframe rendering API contains the following calls:

• BeginRecording: Call this when you want to start a multi-frame render.
• PrepareNewSubFrame: Call this before rendering a new subframe.
• EndRecording: Call this when you want to stop the multi-frame render.

The only call that takes any parameters is BeginRecording. Here is an explanation of the parameters:

Parameter	Description
Samples	The number of sub-frames to accumulate. This parameter overrides the number of path tracing samples in the Volume.
ShutterInterval	The amount of time the shutter is open between two subsequent frames. A value of 0 results in an instant shutter (no motion blur). A value of 1 means there is no (time) gap between two subsequent frames.
ShutterProfile	An animation curve that specifies the shutter position during the shutter interval. Alternatively, you can also provide the time the shutter was fully open; and when the shutter begins closing.

Before calling the accumulation API, the application should also set the desired Time.captureDeltaTime. Refer to Combine animations in a script for an example.