Motion Vectors

A simple overview of rendering dynamic instances.

Flora supports per-instance motion vectors for improved rendering effects such as TAA and motion blur. These rely on screen-space velocity and require consistent tracking of object movement across frames.

---

Enabling Motion Vectors

To enable motion vectors in Flora:

1. Ensure DisablePerObjectMotionVectors is not enabled in your Project Settings.

2. In your scene, enable AllowPerObjectMotionVectors in the SceneSettings component.

Once enabled, Flora will allocate additional memory for instances that require motion vector support.

---

How It Works

If any child object of a prefab contains a MeshRenderer with its Motion Vector Mode set to PerObject, Flora will:

• Detect it automatically at runtime

• Allocate 2 × float4x3 matrices per instance to store previous frame transforms

Tip: Only instances that need motion vectors will incur this memory cost. Make sure motion vectors are enabled only on renderers that require them.

---

Terrain Trees and Details

The SceneSettings component also allows you to enable motion vectors for:

• Terrain Trees

• Terrain Details

When enabled, Flora will evaluate each tree or detail prefab for renderers with motion vectors enabled.

While not a common use case, this allows for advanced effects such as:

• Moving rocks with motion blur

• Debris that reacts to wind or physics with correct velocity tracking

---

Use motion vectors selectively to balance memory usage, especially in scenes with large numbers of animated or physics-driven instances.