UVW projections

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On 31/10/2006 at 06:03, xxxxxxxx wrote:

User Information:
Cinema 4D Version:   9.6 
Platform:   Windows  ;   
Language(s) :     C++  ;

---------
Hello,

i'm trying to extract the UVW coordinates of a polygonal mesh. It all works fine when the texture tag has an "UVW mapping" projection, but I still haven't managed to retrieve the correct mapping coordinates when a Spherical or a Cubic projection is used.

I'm trying to use the function
**
Bool ShdProjectPoint(VolumeData *sd, TexData *tdp, LONG lhit, const Vector &p;, const Vector &n;, Vector *uv)
**
referenced in TexData help:

which extensively uses tdp->im (the inverse of the texture projection matrix).

The problem is when I get the pointer to TexData:

**
TexData* pTexData = pVolumeData- >GetTexData(pObject, 0);     
**

the im field is not initialized, so I manually inverse the matrix:

pTexData- >im = !pTexData->m;

or, additionally:

pTexData- >Initialize();

However none of this seems to work, I get weird UVWs with any kind of projection (but "UVW mapping" one, which i'm retrieving via UVWTag::Get(polygonID) )

Has anybody managed to do get UVW from Spherical/Cubic/... projections? any comments would be appreciated.

Thanks

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On 31/10/2006 at 06:48, xxxxxxxx wrote:

You don't use ShdProjectPoint(), it's a internal function. You should use ProjectPoint instead.

Bool ProjectPoint(TexData* tdp, LONG global_id, const Vector & p, const Vector& n, Vector* uv)
Compute the UVW coordinates for a texture.

Return
Bool
Success of generating the UVW coordinate.

Parameters
TexData* tdp
The texture to use for the UVW coordinates. The caller owns the pointed object.

LONG global_id
The global polygon ID for the UVW coordinates.

const Vector & p
The point for the UVW coordinate.

const Vector & n
The normal for the UVW coordinate.

Vector* uv
The returned UVW coordinate.

Let me know if that helps, also at what point in the Videopost are you calling the function.

cheers,
Matthias

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On 31/10/2006 at 08:49, xxxxxxxx wrote:

Thanks Matthias, I'm afraid it's not working though :(, it always returns FALSE. Here's how I'm using it:

... called from VidePostData::Execute(...) when vps->VP == VP_RENDER

(simplified code)

VolumeData* pVolumeData = vps->vd;
RayObject* pObject = pVolumeData->GetObj(objID);
TexData* pTexData = vps->vd->GetTexData(pObject, 0);

Vector* pPolygonPointNormals = ...

for (LONG p = 0; p < pObject->vcnt; p++)
{
   RayPolygon polygon = pObject->vadr[ p ];               
   LONG polygonGlobalID = pVolumeData->Obj_to_ID(pObject) + p,

Vector vA = pObject->padr[polygon.a];          
   Vector nA = !(ObjectRotationMatrix * pPolygonPointNormals[p * 4]); // normal in world space

UVWStruct UVW;
// assuming the object has a spherical mapping for instance
   Bool res = pVolumeData->ProjectPoint(pTexData , polygonGlobalID, vA, nA, &UVW.a;); // <-- returs false, UVW.a = {0,0,0}

...
}

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On 01/11/2006 at 17:44, xxxxxxxx wrote:

I found out why it's probably not working for you (actually I had trouble to get it to work too). You have to be in VP_INNER to get a result from ProjectPoint, took me some time to figure that out :) Anyway it's working for me, if you have still some problems don't hesitate to ask.

cheers,
Matthias

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On 02/11/2006 at 01:43, xxxxxxxx wrote:

Phew Matthias, its working now ;) thank you so much, you ended up with 3 frustrating days of trial and error.

cheers!

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On 21/12/2006 at 07:53, xxxxxxxx wrote:

I all,

i'm trying to get the projected UVW from volume data and texdata.. but always i'm getting this problem with the spherical projection.

What's the correct way to get stored and prepared UVW in VP_INNER?

I've used ProjectPoint and return me some artifact.

Cheers
Renato T.

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On 22/12/2006 at 15:46, xxxxxxxx wrote:

What i mean is:

When c4d prepare the geometry accessibile in the volumedata i imagine that store in UVW all kind of projection.
But i don't understand how to get the "spherical" or "flat"   transformed UVW. GetUVW fill the UVW polyvector only for the UVW mapped object. I can't trust that ProjectPoint is called when rendering.

thanks in advance and merry xmas to all :)
Renato

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On 31/12/2006 at 05:45, xxxxxxxx wrote:

and.. Happy New Year

Renato

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On 02/01/2007 at 01:30, xxxxxxxx wrote:

In my case I use ProjectPoint, but I haven't noticed any problem with spherical projections (?). In order to be able to retrieve UVW mapping, the object needs to have a Texture Tag, which you cand obtain like this:

  
polygon is an own structure, where pParentObject is a RayObject*  
  
VolumeData* pVD ...  
for (LONG TextureID = 0; (!pAssignedMaterial) && (TextureID < polygon.pParentObject->texcnt); TextureID++)  
{  
   TexData* pTexData = pVD->GetTexData(polygon.pParentObject, TextureID);  
   if (TextureAppliedOnPolygon(pTexData, polygon.localPolygonID, polygon.pParentObject, pVD))   
               pAssignedMaterial = pTexData;  
}  

and then

  
pVD->ProjectPoint(pAssignedMaterial, polygon.globalPolygonID, polygon.vA, polygon.nA, &pUVW-;>a);  
  
same with b and c  

where vA and nA are vectors (position and normal) of the 1st vertex

TextureAppliedOnPolygon implementation is provided somewhere in the sdk

  
BOOL TextureAppliedOnPolygon(TexData* pTexture, LONG localPolygonID, RayObject* pObject, VolumeData* pVD)  
{  
if (pTexture->restrict)  
     {  
          if (pObject->type != O_POLYGON ||   
               pTexture->restrict >= pObject->rscnt ||   
               !pObject->rsadr[pTexture->restrict]) return FALSE;  
  
        if (!(pObject->rsadr[pTexture->restrict][localPolygonID>>5]&(1<<(localPolygonID&31)))) return FALSE;  
    }  
     return TRUE;  
}  

hope it helps

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On 02/01/2007 at 09:39, xxxxxxxx wrote:

Thanks Joesfer,

but i've made exactly the same :)

but maybe that i'm looking in the wrong place.

Thanks
Renato

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On 02/01/2007 at 09:45, xxxxxxxx wrote:

well you've done a little progress in some sense, at least discarding one possible fail... :) luck!

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On 03/01/2007 at 12:10, xxxxxxxx wrote:

Thanks!

Renato