More on Ptex Painting

- Ptex is special kind of mapping where texture 2^n x 2^m is associated with each face. Resolution of each face can be changed dynamically.

- Ptex is very close to microvertex approach because of in microvertex approach patch N x M was associates with every face.

- The big advantages over microvertex painting are - not need UV, every pixel on texture correspond to only one vertex on the patch, it results with much better painting quality.

- Ptex is good for subdivision surface but bad for objects with irregular surfaces that become wrong after subdivision. Currently only quads are supported in 3DC, maybe I will support triangles later.

- Ptex can be set in correspondence with UV-mapping approach because all small textures will be placed on several big textures, so 3DC can export object and textures to be used in any other game/render package. Seamlessness is provided because every patch/small texture is placed on big texture with 1-pixel wide border composed in special way to imitate filtering.

- Objects exported using Ptex can be used in games but it is not too efficient now because every face will produce 4 vertices (instead of 1-2) that will be brought to render engine. This is not too critical issue, but anyway it will give some small speed penalty. Of course game engine can be optimised to avoid this problem using geometry shader but it needs some improvements of engines itself. Anyway, it will work in game engines, it is just performance warning. If proper optimisation will be made in game engines this technique can be used to show displaced objects in close look very well. For example if game engine will get on input 3 streams (vertex position + quad indices + patch parameters) instead of 2(vertex coordinates and uv + triangles indices) then rendering can be performed even in more efficient way.

- Objects can be used in any usual render engines/3D-packages without seams due to reason that was mentioned before (specially filtered border).

- If near future native Ptex export/import will be done too but it is not too critical because of seams problem is almost not existing there.

- Ptex is ideal for baking from voxels to painting approach because there will not exist any uv-overlap issues that are just impossible in this approach.

When your model does not require extreme displacement (by means of texture maps) - and you want to work without the considerations of UV Map seams (very fast) try the Ptex mode.

With the “Texture Editor” Panel open, as well as the Ptex “Tool Options Panel”, you can adjust Ptex resolution, locally, and at any time during the texture painting process - instantly seeing the UV Map changes in real time.

After clicking the “Ptex Icon” at the bottom of the “Painting Tools Panel”, you can designate areas of increased resolution by painting the desired polygons in the Viewport and pressing “Increase Resolution” in the “Tool Options Panel”.

Whatever features you add in the Paint Room can be automatically converted to standard texture maps which can be read by many 3rd party applications.  Ptex provides optimized distribution of texture space, and allows you to work very quickly.

Be aware that texture maps converted from the Ptex Mode are not suitable for modification in external paint apps, like Photoshop. At this time, Ptex is still considered an experimental process for texturing.

The big advantage of Ptex was the ability to increase the resolution of the texture in specific areas. If you didn't have enough resolution for a set of polygons (such as an area with text), you could just select the area and bump up the resolution.

There is a button in the tool palette which says Ptex local resolution when you hover over it. It's an image of a square with four smaller squares in the upper left corner of it. Clicking on it will bring up a bunch of options, at which point you can select which polygons you want to affect by left clicking on them (hold control key and left click to deselect).

Baking Ptex textures on to a mesh with existing UVs: how to bake textures after using the Ptex UV/Texturing method, to a mesh with an existing UV map.
Quite handy if you want to use the Ptex format in 3DCoat as a “storage” format with your high res details, and bake to lower resolution textures as needed.

  • general/paint_workspace/ptex.txt
  • Last modified: 2022/06/11 10:38
  • by carlosan