User parameters are custom parameters that allow you to create or pull in data to be used by Niagara for creating effects.

An example might be creating a new user parameter titled "Static Mesh" that is set to User.StaticMesh; then in Particle Spawn you could use a Sample Static Mesh and set that sample within Blueprints. This provides you with a series of variables which can then be manipulated further such as:

• Particles SampleStaticMesh.MeshColor
• Particles SampleStaticMesh.MeshNormal
• Particles SampleStaticMesh.MeshPosition
• Particles SampleStaticMesh.MeshSampleCoord
• Particles SampleStaticMesh.MeshTangent
• Particles SampleStaticMesh.MeshUV
• Particles SampleStaticMesh.MeshVelocity

For example, you might Set Particles.Position to Particles SampleStaticMesh.MeshPosition

Particles.SpriteAlignment to Particles SampleStaticMesh.MeshTangent

Particles.SpriteFacing to Particles SampleStaticMesh.MeshNormal