# MeshJointInfluence A binding to a joint, which consists of the joint’s index and the weight of that joint’s influence on a vertex. ``` struct MeshJointInfluence ``` ## Overview A vertex may be influenced by one or more joints. The skinned position of that vertex is defined by a set of MeshJointInfluence values whose weights sum to 1. The skinned position is given by: ```swift position = vertexPosition(transformedByJoint: influences[0].jointIndex) * influences[0].weight + vertexPosition(transformedByJoint: influences[1].jointIndex) * influences[1].weight + ... ``` The skinned position of a vertex is a linear combination of the vertex’s position transformed by each joint, with weights given by the MeshJointInfluence values. To transform a vertex position by a joint, the initial vertex position is first transformed by the joint’s inverse bind pose matrix, then by the local-to-parent transform of the joint, and finally by the local-to-parent transform of each of the joint’s parents. ## Topics ### Initializers [`init()`](/documentation/RealityKit/MeshJointInfluence/init()) [`init(jointIndex: Int, weight: Float)`](/documentation/RealityKit/MeshJointInfluence/init(jointIndex:weight:)) ### Instance Properties [`var jointIndex: Int`](/documentation/RealityKit/MeshJointInfluence/jointIndex) [`var weight: Float`](/documentation/RealityKit/MeshJointInfluence/weight) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)