Around UVmapping
  Povanim  for  Blender 
jean-michel soler 2002 - 2004


 Around UVmapping  

Subsurfs deformations 
UVmapping of multiple images 
Solution: material index 
Solution: TexFace
Mixing of luminous effects linked to materials
Path of uvmapped textures
Known problems .
Exporting textures and materials containing UV coordinates is a bit difficult ....

Deformation of the subsurfs
It is relatively easy to export UVmapping when there is only one picture.In this case the only problem we can meet is a slight deformation due to subsurfs.

However the distortion is insignificant if we use only quadriangular faces.With triangular faces, the distortion is greater and depend on the orientation and combination of original faces.....
UVmapping of multiple pictures

The Blender tool "Faceselect"  allows you to attribute more than one UVmapped texture to a mesh. In fact, each face could receive it's own texture. ...

Seeing the result of multi-uvmapping in Blender  is more complicated than attributing the textures themselves.
If we merely try to attribute the pictures by using two textures of the type "Image" in the material of the mesh, the result is not the expected one.
Solution: material index
One of the solutions is to go through the indexes table of material, which is in the edition window of meshes; we then assign a material containing the appropriated image texture to each face or group of faces.

We can go over 16 materials. But it is a restriction only in the Blender indexes table which stay very useful if you want to quickly identify the faces on which such or such images are sticked.

Solution: TexFace
If you don’t need such a precision and tidiness in your work, you can still use the button TexFace in the materials window to display absolutely all the uvmapped images in a quick render.. 

Path of the uvmapped textures
For uvmapping, Povanim doesn’t use the data recorded in the indices table but the picture name attached to each face. With consideration for a few simple rules concerning the storage of the pictures it must be possible to export all the uvmapped coordinates for all the faces .

The script will always connect an under-directory called "textures" to the directory in which the file is exported.

Mixing the effects tied to materials
The variations of the materials classified in the indices table stay attached to each face, what the uvmapped picture may be.

 Pigment_map or Texture_map ?
The depth of pigment or uvmapped texture can be modified in the mixture by playing on their value in the "card" of pigments (mapping) or textures. The notions of pigment_map and texture_map must be increase by reading the official documentation of povray (or, if your are a French-speaking the official French doc ). In povanim, you can export files by choosing one or the other. To do this you have to use the textures pannel which is in the main window of the GUI.

Mixing the pigment with the Uvmapped texture

By default all the exported objects are of light grey. The uvmapped texture is put and blended to this colour up to 50%. You may find the result too white to your tastes. Especially if specular effects are pushed high. To pass round this situation there is three way.

The first one is to put only a texture and to forget the colour. For this, You can find explanation on the finish page, we use the Only Shadow option. This method is all the more practical as it applies to a lone material. Thus parts of the object can me mixed and other not.

However you may wish avoiding any modification of the object appearance when rendered under Blender. To do so, you can use the second solution: the Global Settings, which is located in the Material window of the Povanim GUI. See below: 

You will find two buttons : UV Global Weight and Vertex Global Weight which activate two wipers that you can use to change the weight of the uvmapped texture and vertex colour in the mixture. By giving a 0.0 value to the Vertex Global Weight, it disappears completely leaving the place to the Uvmapped picture.
The problem of this method is to put it into practice globally.  None of the objects escape from this. There is a thrird solution left: modifying the file
Indeed, at the end of the file you will find some definition of that kind :
//List of colors and uvmapped image power 
//this works by object, select the one you want to change
//you can also use the global material setting in the export script

#declare PSphere_012_img=8.763;
#declare PSphere_012_col=0.0;
#declare PSphere_009_img=8.763;
#declare PSphere_009_col=0.0;

It is simply the list of the uvmapped objects names preceded by a "P" for pigment and followed by a suffix that indicates on which part of the mixture colour/picture will act the coefficient.

How to know precisely the location of the textures?

The better manner is to pack them :

And unpack them after:
For the moment the better choice is the one that begins with:
and this whatever the indications given on the left of the table or on the right in brackets may be…
And whatever the indications given on the left of the table or on the right between brackets may be…
This  operation secure the presence of the pictures in a declared directory known by the povray library.

Known problems



Previous             Next

Blender, apprenez, pratiquez, Créez, Ed. Campus Press, coll. Starter Kit
Blender Starter Kit