Wrong Bone Rotation in Assimp

问题

Recently I am working on some way to transform a given bone (rotate by some angle ) using Assimp in visual Studio C++.

I read at many sites procedure to do this and still I am not able to find error with multiple trials for matrix multiplication orders.

What I'm doing is given a model I firstly find the perVertexBone data and then I find bone locations prior any transformation and then represent all vertices in Model using linear weight assignment with bones using perVertexBone data calculated earlier . So , the initial Model looks like this (printing vertices location in Obj format)->

enter image description here

Transformation Process :

Then what I am doing is ( to rotate from neckNode to head portion of Mesh ) :

1.Find the neck node and change
neckNode -> mtransformation = GlmToaiMatrix4x4 ( glm::mat4 ( 1.57f ) )
(I've taken transpose in function for aiMatrix to glm::mat4 conversion).

2.Then I call visitNode ( neckNode ) function and the function is ->

void visitNode(aiNode*node)
{
   string NodeName(node->mName.data);
   glm::mat4 globalTransformation=glm::mat4(1.0f);

   if(boneMap.count(NodeName))
   {
      aiNode*tmp=node;

      while(tmp!=0){
      glm::mat4 mat=aiMatrix4x4ToGlm(tmp->mTransformation);
      globalTransformation=mat*globalTransformation;    // If i change this 
                                            // order whole model is distorted  
      tmp=tmp->mParent;
      }
      boneMap[NodeName]=boneOffsetInverse[NodeName]*globalTransformation*boneOffset[NodeName];
   }

 for(int i=0;i<node->mNumChildren;i++)
 {
    visitNode(node->mChildren[i]);      
 }
}

After this again I calculate boneLocations from this boneMap and assign vertices based on perVertexBonedata and print vertices location which results in a Model like this (printing vertices location in Obj format)->

enter image description here

As you can see the model's neck to head portion is stretched too far away.

Note : Initailly also I call a visitNode() type function to store in boneMap heirarchy of bone skeleton in which I pass mRootNode to print the intial Model vertices .

So can anyone suggest what I'm doing wrong . I have tried many different ways for a week but this was the closest I could achieve.I need this step for a project and this is most crucial step without which I am unable to progress in this .

Any suggestions will be appreciated.

来源：https://stackoverflow.com/questions/62340023/wrong-bone-rotation-in-assimp