【Ptex– 材质模块 – Houdini帮助文档中文版】
Ptex is a new format for texture maps. With Ptex there is no need to generate texture coordinates. It performs high quality filtering between polygons/patches, has subdivision support, and is open source.
–ptex是一种新的纹理贴图格式。使用ptex，不需要创建纹理坐标。它在多边形/Path上有高质量的过滤，有细分控制，并且是开源的。
Ptex allows you to apply separate textures for each face of a subdivisions or polygon mesh, and can store thousands of texture images in a single file. Houdini has support for Ptex files in a few places.
–Ptex可以让你给细分体或多边形网格的每个面运用分离的纹理，并起可以在一个文件中存储数以千计的纹理图像。Houdini支持Ptex文件。
The environment function only recognizes Houdini filters and maps these to the ptex filters. The current mapping of Houdini filters to Ptex filters is:
–environment 函数只会组织Houdini的过滤器，并把它们映射到Ptex过滤器上。当前Houdini用于Ptex的过滤器是（下面都是一些模糊方式）：
point point
box box
cone gaussian
hanning gaussian
blackman gaussian
gaussian gaussian
sinc catmullrom
catmullrom catmullrom
mitchell mitchell
gptex
The gptex program allows you to take individual maps for every polygon in your model and generate a .ptx texture for the model.
—gptex程序可以让你从你的模型的每个多边形上获取独立额贴图，并给模型生成一个.ptx文件。
gptex [-f maplist] geofile ptexfile [mapfiles…]
Create a Ptex map for a geometry file and all the matching texture maps. Texture maps can either be read from a file (using the -f option) or specified on the command line.
—给几何体创建一个ptx贴图文件，并且会匹配纹理贴图。纹理贴图可以从一个文件中读取或在命令行指定。
| -f mapfile | Text file containing a texture map per face
–文本文件包含每个面的一个纹理贴图。 |
Example
% gptex box.geo box.ptx face0.rat face0.exr face1.pic face2.tif face3.pic face4.pic face5.pic
Will generate the box.ptx texture file from the box and the corresponding 6 texture maps.
—它会从方盒以及6给纹理贴图上生成一个名为box.ptx纹理文件。
isixpack
isixpack can generate .ptx files for reflection/environment maps. These maps provide better filtering when there’s lots of blurring when compared to using .rat files.
—isixpack可以生成反射/环境的ptx贴图。当有很多模糊时，和使用rat文件相比，这些贴图可以提供一个更好的过滤。
VOPs
There are new VOPs to access ptex files, such as ptexture.
—有新的VOPs来获取ptex文件，如ptexture节点。
