Decomposing Material Mapper Transform Matrix

By Madhukar Moogala

Question: Is it possible to return origin, rotation, the x-y- scale factors and offset values from the Matrix3d of  MaterialMapper.Transform ?

Answer: Yes ,it is possible to retrieve details from  transform matrix of an Entity's material mapper , I have demonstrate below assuming user has selected a 3DFace entity on which Material is applied using MaterialMap command iteractively and adjusted rotation ,offset and scale as per user needs.

Somethink like this as shown in below screenshot.

Note : If AcGiMapper::autoTransform() is set to kObject or kModel, then you will not be able to recover the scale/translation/rotation, as the GS will dynamically compute it based on whatever entity/selection the mapper is applied to.

C++ Code :

static void ASDKMyGroupTestMapper()    {    Acad::ErrorStatus es;    ads_name entres;    ads_point ptres;    AcGeVector3d scale;    AcGeVector3d rotation;    AcGeVector3d translate;    AcGeMatrix3d mat;    /*Select Entity*/    if(RTNORM != acedEntSel(_T("Select 3DFace entity"),entres,ptres))    return;    AcDbObjectId objId = AcDbObjectId::kNull;    if((es = acdbGetObjectId(objId,entres) ) != Acad::eOk)    return;    AcDbEntity* pFaceEntity = NULL;    if ((es = acdbOpenAcDbEntity(pFaceEntity,objId,AcDb::kForRead) )    != Acad::eOk) return;         if(pFaceEntity->isA() == AcDbFace::desc())    {    AcDbFace* pFace =  AcDbFace::cast(pFaceEntity);    AcGiMapper mapper;    AcDbMaterial* material = NULL;    AcGiMaterialMap materialMap;    if((es = acdbOpenObject((AcDbObject*&)material,pFace->materialId(),    AcDb::kForRead))!= Acad::eOk)    {    pFaceEntity->close();    return;    }    double strength=0.0;    AcGiMaterialColor color;    /*Get diffuse gives details about Texture in general,    and what component to be used to retrieve materialmap    can be found from AcDbMaterial::channelFlags*/                material->diffuse(color,materialMap);         mat = materialMap.mapper().transform();    if(materialMap.mapper().autoTransform() < 2)    {    decomposeMatrix(mat,scale,rotation,translate);    }         pFaceEntity->close();    material->close();                   }    acutPrintf(_T("n Rotation Angle : %2f n"),rotation.z*(180/M_PI));    acutPrintf(_T("n Scale X : %2f , Scale Y : %2f n"),scale.x,scale.y);    /*You may have to negate offset values of Translate vector for correct sign*/    acutPrintf(_T("n Translation Vector: %2f,%2f n"),-translate.x,-translate.y);              }         static void decomposeMatrix (const AcGeMatrix3d &mat,    AcGeVector3d &scale,    AcGeVector3d &rotate,    AcGeVector3d &translate)    {    // Scale - assume always positive, and must be non-zero    scale.x = 1.0/AcGeVector3d(mat(0,0), mat(0,1), mat(0,2)).length();    scale.y = 1.0/AcGeV
ector3d(mat(1,0), mat(1,1), mat(1,2)).length();    scale.z = 1.0/AcGeVector3d(mat(2,0), mat(2,1), mat(2,2)).length();    if (scale.x == 0.0)    scale.x = 1.0;    if (scale.y == 0.0)    scale.y = 1.0;    if (scale.z == 0.0)    scale.z = 1.0;         // Translation    translate =  mat.translation();    translate.x *= scale.x;    translate.y *= scale.y;    translate.z *= scale.z;         // Rotation – assume only rotation about the Z axis    double acosVal = mat(0,0) / scale.x;    if (acosVal > 1.0)    acosVal = 1.0;    else if (acosVal < -1.0)    acosVal = -1.0;         double zAngle = acos(acosVal);    assert(0.0

C# .NET code :

[CommandMethod("TestMapper")]    public void Mappertest()    {    Document activeDoc = Application.DocumentManager.MdiActiveDocument;    Database db = activeDoc.Database;    Editor ed = activeDoc.Editor;    PromptEntityResult oRes = ed.GetEntity("Select 3dFace");    if (oRes.Status != PromptStatus.OK) return;    Vector3d scale = default(Vector3d);    Vector3d rotate = default(Vector3d);    Vector3d translate = default(Vector3d);         using (Transaction oTrans = db.TransactionManager.StartTransaction())    {    Face oFace = oTrans.GetObject(oRes.ObjectId, OpenMode.ForRead) as Face;         if (oFace != null)    {    string strMat = oFace.Material;    ObjectId nMat = oFace.MaterialId;    Material material = oTrans.GetObject(nMat,OpenMode.ForRead) as Material;    ChannelFlags cFlasg = material.ChannelFlags;    MaterialDiffuseComponent mDC = material.Diffuse;                                      MaterialMap materialMap = mDC.Map;                                 Matrix3d tranform = materialMap.Mapper.Transform;    double scaleD = tranform.GetScale();                    if (materialMap.Mapper.AutoTransform == AutoTransform.InheritAutoTransform ||        materialMap.Mapper.AutoTransform == AutoTransform.None)    DecomposeMatrix(tranform , ref scale, ref rotate, ref translate);    /*You have negate offset value to reflect correct sign*/    ed.WriteMessage("Rotation Angle : " + rotate.Z * (180 / Math.PI) + "n"                    + "Scale X :" + Math.Round(scale.X) + " Scale Y : " + Math.Round(scale.Y) + "n" +                    "Translation Vector offset Values :" + -translate.X + "," + -translate.Y);              }    oTrans.Commit();    }               }         public void DecomposeMatrix( Matrix3d mat, ref Vector3d scale, ref Vector3d rotate, ref Vector3d translate)    {    // Scale - assume always positive, and must be non-zero    Vector3d v3dOne= new Vector3d(mat[0, 0], mat[0, 1], mat[0, 2]);    Vector3d v3dTwo = new Vector3d(mat[1, 0], mat[1, 1], mat[1, 2]);    Vector3d v3dThree = new Vector3d(mat[2, 0], mat[2, 1], mat[2, 2]);         //    scale = new Vector3d(v3dOne.Length, v3dTwo.Length, v3dThree.Length);    scale = new Vector3d(1/v3dOne.Length, 1/v3dTwo.Length, 1/v3dThree.Length);    if (scale.X == 0)    scale = new Vector3d(1.0, scale.Y, scale.Z);    if (scale.Y == 0)    scale = new Vector3d(scale.X, 1.0, scale.Z);    if (scale.Z == 0)    scale = new Vector3d(scale.X, scale.Y, 1.0);    // Translation    translate = mat.Translation;    translate = new Vector3d(translate.X * Math.Round(scale.X), translate.Y*Math.Round(scale.Y), translate.Z*Math.Round(scale.Z));    // Rotation – assume only rotation about the Z axis    double acosValue = mat[0, 0] / scale.X;    if (acosValue > 1.0)    acosValue = 1.0;    else if (acosValue < -1.0)    acosValue = -1.0;    double zAngle = Math.Acos(acosValue);    Debug.Assert(0.0

Output :

Rotation Angle : 60.0000016696521

Scale X :1 Scale Y : 2

Translation Vector offset Values :12,15