Fast way to get polygon index per vertex [SOLVED]



  • On 05/03/2015 at 12:22, xxxxxxxx wrote:

    User Information:
    Cinema 4D Version:   14,15,16 
    Platform:   Windows  ;   
    Language(s) :     C++  ;

    ---------
    Hi,

    I am using this code to get the polygon index that every vertex belongs to, but it's very slow.
    Is there a faster way to do it?

    const CPolygon *pPolys = pobj->GetPolygonR();
    for (int i = 0; i<pointCnt; i++)
    {
    	for (int j=0; j<polyCnt; j++)
    	{
    		if (pPolys[j].a == i)
    		myIndexArray[i] = j;		//	myIndexArray is an integer BaseArray that is storing the polygon indices
    	
    	}
    }
    

    Since I am manually going over every vertex and from it check every polygon, the operation is very slow. I am hoping someone can give a faster alternative.

    Thanks



  • On 05/03/2015 at 12:45, xxxxxxxx wrote:

    not sure, but a little better version:

      
    const CPolygon *pPolys = pobj->GetPolygonR();
    for (int i = 0; i<pointCnt; i++)
    {
    	for (int j=0; j<polyCnt; j++)
    	{
    		if (pPolys[j].a == i)
    		{
    			myIndexArray[i] = j;		//	myIndexArray is an integer BaseArray that is storing the polygon indices
    			break;
    		}
    		else if (pPolys[j].b == i)
    		{
    			myIndexArray[i] = j;		//	myIndexArray is an integer BaseArray that is storing the polygon indices
    			break;
    		}
    		else if (pPolys[j].c == i)
    		{
    			myIndexArray[i] = j;		//	myIndexArray is an integer BaseArray that is storing the polygon indices
    			break;
    		}
    		else if (pPolys[j].d == i)
    		{
    			myIndexArray[i] = j;		//	myIndexArray is an integer BaseArray that is storing the polygon indices
    			break;
    		}
    	}
    }
    


  • On 05/03/2015 at 12:55, xxxxxxxx wrote:

    and I think this version will be much better:

    const CPolygon *pPolys = pobj->GetPolygonR();
    //for(int i = 0; i<myIndexArray.size();++i)
    //{
    //	myIndexArray _= -1;_
     _//}_
     _  
    _
     _for(int j = 0; j <polyCnt; ++j)_
     _{_
     _	 myIndexArray[pPolys[j].a] = j;_
     _	 myIndexArray[pPolys[j].b] = j;_
     _	 myIndexArray[pPolys[j].c] = j;_
     _	 myIndexArray[pPolys[j].d] = j;_
     _}_
     _
    

    edit: the point can have many polygons, so depends on your needs you can modify it to get all polygons "not only last poly index"_
    _
    _
    __



  • On 05/03/2015 at 13:18, xxxxxxxx wrote:

    Thanks a lot Mohamed. I ended up using your first suggestion. Using BREAK was the key to make the operation go faster.


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