手机硬件限制，很多PC上的渲染优化技术是没办法直接拿过来用的。目前有些游戏为了实现多部队战斗的效果，各种降低骨骼数目，模型面数的方案，但都逃不过骨骼动画计算这一环节。
在上个公司的时候，自己瞎想了一张方案，没想到最后还写出来了， 没想到最后还用上了。。。
先上张图，里面有100个士兵和10个萌宝宝的场景，每个角色的动作是分开控制的，在小米3上可以60fps的帧率流畅运行，之前也尝试过，300多个角色带动画也可以55左右的fps运行
先说明一下这套方案的优缺点：
优点：可不用计算骨骼动画，并能流畅播放骨骼动画（其实已经不是骨骼动画了）；每个角色动作也可以单独控制；对cpu很小消耗；
缺点：动作切换没有过渡(群体作战的时候，这点基本不影响审美)；对内存占用有一点消耗（其实也还好）
再说明方案思路：
为了省掉骨骼动画计算这一环节，就不能用现有骨骼动画系统。那么可选的方案也只有顶点变形动画了，而传统的顶点动画不管是内存占用还是不低的，而且unity支持也不算好。
那么既然只能选顶点动画且为了降低内存消耗，那么可以通过改写shader，通过gpu来插值实现顶点动画播放骨骼动画的效果。
shader插值的方案确实也不少，但结合具体实现上来，我选了两种实现相对简单的方案：
1.vertex shader里通过每帧采样的uv偏移采样纹理来控制顶点的位置，当我已经在pc端实现的时候才突然发现一个显而易见的问题：在vertex shader里采样纹理，pc端部分显卡是支持的，但手机gpu就不要想了。
2.于是只能第二种方案:还是vextex shader里插值顶点来播放动画，那么就有一个问题，vertex data从哪里来？ unity的mesh结构有很多通道，顶点，颜色，uv，uv2，法线，切线。。这些通道里面除了color（主要是精度问题）和uv（还是必须给纹理坐标一个位置的）通道以外我都可以用来存顶点数据，然后通过控制时间点来组合顶点进行插值，然而还有个问题需要解决，这种方式一个mesh只能插值4个关键顶点，那么较长的动画怎么办呢，可以通过提前生成多个mesh，来切换。
动画截取可以通过unity的BakeMesh函数或者美工来帮助实现，下面是组合mesh 的代码：
byte[] Make(Mesh mesh1, Mesh mesh2, Mesh mesh3, Mesh mesh4, float clipTimeLenghts, float frame2Pos, float frame3Pos){Mesh[] meshs = new Mesh[] { mesh1, mesh2, mesh3, mesh4};VertexAnimationResManager.ClipMeshData meshData = new VertexAnimationResManager.ClipMeshData();meshData.subMeshCount = meshs[0].subMeshCount;int count = meshs[0].vertices.Length;//顶点if (meshs[0].vertices != null && meshs[0].vertices.Length > 0){meshData.vertexBuffer = new float[count * 3];for (int i = 0; i < meshs[0].vertices.Length; i++){meshData.vertexBuffer[i * 3] = meshs[0].vertices[i].x;meshData.vertexBuffer[i * 3 + 1] = meshs[0].vertices[i].y;meshData.vertexBuffer[i * 3 + 2] = meshs[0].vertices[i].z;} }//uvif (meshs[0].uv != null && meshs[0].uv.Length > 0){meshData.uvBuffer = new float[count * 2];for (int i = 0; i < meshs[0].vertices.Length; i++){meshData.uvBuffer[i * 2] = meshs[0].uv[i].x;meshData.uvBuffer[i * 2 + 1] = meshs[0].uv[i].y;}//GCHandle verSrcHand = GCHandle.Alloc(meshs[0].uv, GCHandleType.Pinned);//Marshal.Copy(verSrcHand.AddrOfPinnedObject(), meshData.uvBuffer, 0, meshData.uvBuffer.Length);//verSrcHand.Free(); }//法线 这里用来存动画第二帧的顶点信息if (meshs[1].vertices != null && meshs[1].vertices.Length > 0){meshData.normalBuffer = new float[count * 3];for (int i = 0; i < meshs[0].vertices.Length; i++){meshData.normalBuffer[i * 3] = meshs[1].vertices[i].x;meshData.normalBuffer[i * 3 + 1] = meshs[1].vertices[i].y;meshData.normalBuffer[i * 3 + 2] = meshs[1].vertices[i].z;}}//切线 这里用来存动画第三帧的顶点信息if (meshs[2].vertices != null && meshs[2].vertices.Length > 0){meshData.tangentBuffer = new float[count * 4];for (int i = 0; i < meshs[0].vertices.Length; i++){meshData.tangentBuffer[i * 4] = meshs[2].vertices[i].x;meshData.tangentBuffer[i * 4 + 1] = meshs[2].vertices[i].y;meshData.tangentBuffer[i * 4 + 2] = meshs[2].vertices[i].z;meshData.tangentBuffer[i * 4 + 3] = meshs[3].vertices[i].x;}}//UV2 用来存第四个关键帧率的 顶点YZ 坐标 X坐标由切线的W通道来存if (meshs[3].vertices != null && meshs[3].vertices.Length > 0){meshData.uv2Buffer = new float[count * 2];for (int i = 0; i < meshs[0].vertices.Length; i++){meshData.uv2Buffer[i * 2] = meshs[3].vertices[i].y;meshData.uv2Buffer[i * 2 + 1] = meshs[3].vertices[i].z;} }//颜色 用来存第5个顶点信息//if (meshs[Indexs[4]].vertices != null && meshs[Indexs[4]].vertices.Length > 0)//{// //颜色通道貌似没有负数,且范围为0到1 所有这里需要将模型顶点映射到[0,1]之间，映射范围为[-1,1]之间// meshData.colorBuffer = new float[count * 4];// for (int i = 0; i < meshs[Indexs[4]].vertices.Length; i++)// {// meshData.colorBuffer[i * 4] = (meshs[Indexs[4]].vertices[i].x * 0.5f) + 0.5f;// meshData.colorBuffer[i * 4 + 1] = (meshs[Indexs[4]].vertices[i].y * 0.5f) + 0.5f;// meshData.colorBuffer[i * 4 + 2] = (meshs[Indexs[4]].vertices[i].z * 0.5f) + 0.5f;// }//}count = 0;int len = 0;meshData.subMeshTriangleLens = new int[meshData.subMeshCount];for (int i = 0; i < meshData.subMeshCount; i++){len = meshs[0].GetTriangles(i).Length;count += len;meshData.subMeshTriangleLens[i] = len;}meshData.triangleBuffer = new int[count];len = 0;for (int i = 0; i < meshData.subMeshCount; i++){meshs[0].GetTriangles(i).CopyTo(meshData.triangleBuffer, len);len += meshData.subMeshTriangleLens[i];}ByteBuffer bbuffer = new ByteBuffer();bbuffer.WriteFloat(clipTimeLenghts);bbuffer.WriteFloat(frame2Pos);bbuffer.WriteFloat(frame3Pos);bbuffer.WriteInt(meshs[0].subMeshCount);for(int i=0;i<meshData.subMeshTriangleLens.Length;i++ ){bbuffer.WriteInt(meshData.subMeshTriangleLens[i]);}bbuffer.WriteInt(meshData.triangleBuffer.Length);for (int i = 0; i < meshData.triangleBuffer.Length; i++){ bbuffer.WriteInt(meshData.triangleBuffer[i]);}bbuffer.WriteInt(meshData.vertexBuffer.Length);for (int i = 0; i < meshData.vertexBuffer.Length; i++){bbuffer.WriteFloat(meshData.vertexBuffer[i]);}bbuffer.WriteInt(meshData.normalBuffer.Length);for (int i = 0; i < meshData.normalBuffer.Length; i++){bbuffer.WriteFloat(meshData.normalBuffer[i]);}bbuffer.WriteInt(meshData.tangentBuffer.Length);for (int i = 0; i < meshData.tangentBuffer.Length; i++){bbuffer.WriteFloat(meshData.tangentBuffer[i]);}bbuffer.WriteInt(meshData.uvBuffer.Length);for (int i = 0; i < meshData.uvBuffer.Length; i++){bbuffer.WriteFloat(meshData.uvBuffer[i]);}bbuffer.WriteInt(meshData.uv2Buffer.Length);for (int i = 0; i < meshData.uv2Buffer.Length; i++){bbuffer.WriteFloat(meshData.uv2Buffer[i]);} return bbuffer.ToBytes();}
截取好后，保存为自己的二进制文件，运行的时候加载并 解析的代码如下：
public void AddAnimationInfo(string aniName, byte[] clipData){VertexAnimationClipInfo clipInfo = null;AnimationClipInfos.TryGetValue(aniName, out clipInfo);if(clipInfo!=null){Debug.LogError("animation clip has exits！");return; }clipInfo = new VertexAnimationClipInfo();ByteBuffer bbuffer = new ByteBuffer(clipData);int Count = bbuffer.ReadInt();for (int i = 0; i < Count; i++){ClipMeshData meshData = GetMeshData(bbuffer);clipInfo.clipTotalTimeLen += meshData.timeLenth;clipInfo.clipLenghts.Add(meshData.timeLenth);clipInfo.everyClipFrameTimePoints.Add(new Vector3(meshData.Frame2TimePoint, meshData.Frame3TimePoint)); //,meshData.Frame4TimePointclipInfo.clipMeshs.Add(meshData.GenMesh());}bbuffer.Close();AnimationClipInfos.Add(aniName, clipInfo);}
VertexAnimationClipInfo定义如下：
[Serializable]public class VertexAnimationClipInfo{public float clipTotalTimeLen = 0;public List<Mesh> clipMeshs = new List<Mesh>();public List<Vector2> everyClipFrameTimePoints = new List<Vector2>();public List<float> clipLenghts = new List<float>();}
ClipMeshData定义如下：
public class ClipMeshData{public float timeLenth;///Frame1TimePoint =0 Frame4TimePoint = 1public float Frame2TimePoint = 0.333f;public float Frame3TimePoint = 0.666f;//public float Frame4TimePoint = 0.75f;public int subMeshCount;public int[] subMeshTriangleLens;public int[] triangleBuffer;public float[] vertexBuffer;public float[] normalBuffer;public float[] tangentBuffer;public float[] uvBuffer;public float[] uv2Buffer;//public float[] colorBuffer;public Mesh GenMesh(){ Mesh mesh = new Mesh();int vertexCount = vertexBuffer.Length / 3;mesh.subMeshCount = subMeshCount;//顶点Vector3[] vertexs = new Vector3[vertexCount];for (int i = 0; i < vertexCount; i++){vertexs[i] = new Vector3(vertexBuffer[i * 3], vertexBuffer[i * 3 + 1], vertexBuffer[i * 3 + 2]);}mesh.vertices = vertexs; //uvVector2[] uv = new Vector2[vertexCount];for (int i = 0; i < uv.Length; i++){uv[i] = new Vector2(uvBuffer[i * 2], uvBuffer[i * 2 + 1]);}mesh.uv = uv;//uv2Vector2[] uv2 = new Vector2[vertexCount];for (int i = 0; i < uv.Length; i++){uv2[i] = new Vector2(uv2Buffer[i * 2], uv2Buffer[i * 2 + 1]);}mesh.uv2 = uv2;//法线 Vector3[] normals = new Vector3[vertexCount];for (int i = 0; i < normals.Length; i++){normals[i] = new Vector3(normalBuffer[i * 3], normalBuffer[i * 3 + 1], normalBuffer[i * 3 + 2]);} mesh.normals = normals;//切线var tangents = new Vector4[vertexCount]; for (int i = 0; i < tangents.Length; i++){tangents[i] = new Vector4(tangentBuffer[i * 4], tangentBuffer[i * 4 + 1], tangentBuffer[i * 4 + 2], tangentBuffer[i * 4 + 3]);} mesh.tangents = tangents;////颜色//Color[] colors = new Color[colorBuffer.Length / 4];//for (int i = 0; i < colors.Length; i++)//{// colors[i] = new Vector4(colorBuffer[i * 4], colorBuffer[i * 4 + 1], colorBuffer[i * 4 + 2], 1);//}//mesh.colors = colors;//三角形 int startIndex = 0;int bufferLen = 0;for (int i = 0; i < subMeshCount; i++){bufferLen = subMeshTriangleLens[i];if (bufferLen <= 0) continue;var triIndexBuffer = new int[bufferLen];Array.Copy(triangleBuffer, startIndex, triIndexBuffer, 0, bufferLen);mesh.SetTriangles(triIndexBuffer, i);startIndex += bufferLen;}return mesh;}}
播放动画切换对应的mesh就可以了，下面是gpu插值所用的shader代码：
Shader "LXZ_TEST/VertexAnimation-NoColorBuf" {Properties {_MainTex ("Base (RGB)", 2D) = "white" {}_CurTime("Time", Float) = 0 _Frame2Time("Frame2Time", Float) = 0.333_Frame3Time("Frame3Time", Float) = 0.666_Color ("MainColor", color) = (1,1,1,1)}SubShader {// Tags { "QUEUE"="Geometry" "RenderType"="Opaque" }Pass { Blend SrcAlpha OneMinusSrcAlpha CGPROGRAM#pragma vertex vert#pragma fragment frag// #include "UnityCG.cginc" #pragma glsl_no_auto_normalization sampler2D _MainTex;float _CurTime;float _Frame2Time;float _Frame3Time;float4 _Color;struct appdata {float4 vertex : POSITION;float3 vertex1 : NORMAL;float4 vertex2 : TANGENT;float2 texcoord : TEXCOORD0;float2 vertex3: TEXCOORD1;//float3 vertex4: COLOR;}; struct v2f {float4 pos : POSITION;float2 uv : TEXCOORD0;};v2f vert(appdata v) {v2f result; float a = _CurTime - _Frame2Time;float b = _CurTime - _Frame3Time;float3 vec; float3 vertex3 = float3(v.vertex2.w,v.vertex3.xy);if(a<0)vec = v.vertex.xyz + (v.vertex1 - v.vertex.xyz)* _CurTime/_Frame2Time;else if(a>=0 && b<0){ vec = v.vertex1 + (v.vertex2.xyz - v.vertex1)* a/(_Frame3Time-_Frame2Time); } elsevec = v.vertex2.xyz + (vertex3 - v.vertex2.xyz)* b/(1-_Frame3Time); result.pos = mul(UNITY_MATRIX_MVP, float4(vec,1)); //result.pos = mul(UNITY_MATRIX_MVP, float4(v.vertex1.xyz,1)); //result.pos = mul(UNITY_MATRIX_MVP, float4(v.vertex2.xyz,1)); // result.pos = mul(UNITY_MATRIX_MVP, float4(vertex3.xyz,1)); // result.pos = mul(UNITY_MATRIX_MVP, float4(vertex4.xyz,1)); result.uv = v.texcoord; return result;}float4 frag(v2f i) : COLOR{float4 color = tex2D(_MainTex, i.uv);return color *_Color;}ENDCG }} FallBack "Diffuse"}
如果各位还有更好的方案，欢迎交流。。不擅长文字的东西，所以直接贴代码了，有需要可以与我连续交流。。。
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- 您好，为了更好的阅读体验，建议给代码加上高亮。