Mesh.boneWeights

Description

The BoneWeight for each vertex in the Mesh, which represents 4 bones per vertex.

The size of this array is either Mesh.vertexCount or zero. The array is sorted by vertex index.

Note that this property uses BoneWeight structs, which represent exactly 4 bone weights per vertex. The newer BoneWeight1 struct describes a single bone weight, and it can be used with the associated Mesh.GetAllBoneWeights, Mesh.SetBoneWeights and Mesh.GetBonesPerVertex APIs to describe up to 255 bone weights per vertex. It is preferable to use BoneWeight1 and its associated APIs; they offer more flexibility, and might result in small performance benefits as Unity does not have to perform unnessary conversion operations.

Additional resources: Mesh.GetAllBoneWeights, Mesh.SetBoneWeights, Mesh.GetBonesPerVertex, Mesh.GetBoneWeights, ModelImporter.maxBonesPerVertex, QualitySettings.skinWeights, SkinnedMeshRenderer.quality.

using UnityEngine;

public class SkinnedMeshExample : MonoBehaviour{
    void Start(){
        gameObject.AddComponent<Animation>();
        gameObject.AddComponent<SkinnedMeshRenderer>();
        SkinnedMeshRenderer rend = GetComponent<SkinnedMeshRenderer>();
        Animation anim = GetComponent<Animation>();

        // Build basic mesh
        Mesh mesh = new Mesh();
        mesh.vertices = new Vector3[] {new Vector3(-1, 0, 0), new Vector3(1, 0, 0), new Vector3(-1, 5, 0), new Vector3(1, 5, 0)};
        mesh.uv = new Vector2[] {new Vector2(0, 0), new Vector2(1, 0), new Vector2(0, 1), new Vector2(1, 1)};
        mesh.triangles = new int[] { 0, 3, 1, 0, 2, 3 };
        mesh.RecalculateNormals();

        // Assign mesh to mesh filter & renderer
        rend.material = new Material(Shader.Find("Diffuse"));

        // Assign bone weights to mesh
        // We use 2 bones. One for the lower vertices, one for the upper vertices.
        BoneWeight[] weights = new BoneWeight[4];

        weights[0].boneIndex0 = 0;
        weights[0].weight0 = 1;

        weights[1].boneIndex0 = 0;
        weights[1].weight0 = 1;

        weights[2].boneIndex0 = 1;
        weights[2].weight0 = 1;

        weights[3].boneIndex0 = 1;
        weights[3].weight0 = 1;

        // A BoneWeights array (weights) was just created and the boneIndex and weight assigned.
        // The weights array will now be assigned to the boneWeights array in the Mesh.
        mesh.boneWeights = weights;

        // Create Bone Transforms and Bind poses
        // One bone at the bottom and one at the top
        Transform[] bones = new Transform[2];
        Matrix4x4[] bindPoses = new Matrix4x4[2];

        bones[0] = new GameObject("Lower").transform;
        bones[0].parent = transform;
        // Set the position relative to the parent
        bones[0].localRotation = Quaternion.identity;
        bones[0].localPosition = Vector3.zero;

        // The bind pose is bone's inverse transformation matrix
        // In this case the matrix we also make this matrix relative to the root
        // So that we can move the root game object around freely
        bindPoses[0] = bones[0].worldToLocalMatrix * transform.localToWorldMatrix;

        bones[1] = new GameObject("Upper").transform;
        bones[1].parent = transform;
        // Set the position relative to the parent
        bones[1].localRotation = Quaternion.identity;
        bones[1].localPosition = new Vector3(0, 5, 0);
        // The bind pose is bone's inverse transformation matrix
        // In this case the matrix we also make this matrix relative to the root
        // So that we can move the root game object around freely
        bindPoses[1] = bones[1].worldToLocalMatrix * transform.localToWorldMatrix;

        // assign the bindPoses array to the bindposes array which is part of the mesh.
        mesh.bindposes = bindPoses;

        // Assign bones and bind poses
        rend.bones = bones;
        rend.sharedMesh = mesh;

        // Assign a simple waving animation to the bottom bone
        AnimationCurve curve = new AnimationCurve();
        curve.keys = new Keyframe[] {new Keyframe(0, 0, 0, 0), new Keyframe(1, 3, 0, 0), new Keyframe(2, 0.0F, 0, 0)};

        // Create the clip with the curve
        AnimationClip clip = new AnimationClip();
        clip.SetCurve("Lower", typeof(Transform), "m_LocalPosition.z", curve);
        clip.legacy = true;
        clip.wrapMode = WrapMode.Loop;

        // Add and play the clip
        anim.AddClip(clip, "test");
        anim.Play("test");
    }
}