get mesh positions in ofxassimploader

[minusplusminus]

Hi,

I've mentioned that Assimp model loader doesn't have positions of meshes. I've seen that the data is available in the Assimp library, but not interpreted in the addon.

I've allready made a start, but couldn't get the positions right.

 //-------------------------------------------
 ofPoint ofxAssimpModelLoader::getMeshPosition(int num){
ofPoint pos;
if((int)scene->mNumMeshes<=num){
    ofLogError("ofxAssimpModelLoader") << "getMesh(): mesh id " << num
    << " out of range for total num meshes: " << scene->mNumMeshes;
    return pos;
}

aiVector3D* verticles = scene->mMeshes[num]->mVertices;

ofPoint pt = ofPoint(verticles->x*normalizedScale,
                     verticles->y*normalizedScale ,
                     verticles->z*normalizedScale );

pt.rotate(-90, ofVec3f(1,0,0));
return pt;

}

[minusplusminus]

I've figured it out:

   typedef struct
   {
       ofVec3f scale;
       ofVec3f rotation;
       ofVec3f position;
   } meshTranslation;

     meshTranslation ofxAssimpModelLoader::getMeshTranslation(int meshIndex)
{
    meshTranslation translation;
    aiMatrix4x4 childTransformation = scene->mRootNode->mChildren[meshIndex]->mTransformation;

    aiVector3t<float> scaling;
    aiQuaterniont<float> rotation;
    aiVector3t<float> position;

    childTransformation.Decompose(scaling, rotation,position);

    translation.position.set(position.x,position.y,position.z);
    translation.position = translation.position*normalizedScale;
    translation.scale.set(scaling.x, scaling.y,scaling.z);
    translation.rotation.set(rotation.x,rotation.y,rotation.z);

    return translation;
}

[bilderbuchi]

pinging @openframeworks/2d-3d @arturoc

[arturoc]

probably what we need is to internally represent ofxAssimpModelLoader meshes using an of3dPrimitive which already includes a node so you can easily query for it's position, rotation... also it will probably make the code cleaner

[minusplusminus]

 of3dPrimitive ofxAssimpModelLoader::getMeshTranslation(int meshIndex)
 {
     of3dPrimitive translation;
     if( scene->mRootNode != NULL && meshIndex < scene->mRootNode->mNumChildren)
     {
         meshIndex = ofClamp(meshIndex,0, scene->mRootNode->mNumChildren);

         aiMatrix4x4 childTransformation = scene->mRootNode->mChildren[meshIndex]->mTransformation;

         aiVector3t<float> scaling;
         aiQuaterniont<float> rotation;
         aiVector3t<float> position;

    childTransformation.Decompose(scaling, rotation,position);

         ofQuaternion q;
         q.set(rotation.w, rotation.x, rotation.y, rotation.z);

         translation.setPosition(position.x,position.y,position.z);
         translation.setPosition(translation.getPosition()*normalizedScale);
         translation.setScale(scaling.x, scaling.y,scaling.z);
         translation.rotateAround(q, ofPoint(rotation.x,rotation.y,rotation.z));
     }
     return translation;
 }

I'm unsure about the rotation. What do you think @arturoc ?

[arturoc]

mmh, no that doesn't make much sense, an of3dPrimitive is an object that has a mesh and an ofNode so it can represent a geometry and it's transformations. what i was saying is that ofxAssimpModelLoader could use of3dPrimitives instead of ofMesh to reprensent the different meshes and at the same time the transformations for each of those meshes, then a function like the one you propose would just need to call getPosition/Rotation... on the corresponding primitive.

it's kind of a big change and if we are going to do that it's probably worth looking into porting the addon to use assimp 3