Unity Ply网格读取
Ply格式说明
The version 1.0 PLY format, 详细参见：https://ww2.mathworks.cn/help/vision/ug/the-ply-format.html
File Header
文件头示例’{}‘为说明：
ply {文件头}
format binary_big_endian 1.0 {数据格式以及版本}
element vertex 9200 {定义vertex元素}
property float x {定义属性}
property float y
property float z
element face 18000 {定义面元素}
property list uchar int vertex_indices
end_header {这行后面就是数据了}
其中，format <data format> <PLY version> 中的<data format>支持（little/big endian refers to the byte ordering of multi-byte data）：
- ascii
- binary_little_endian
- binary_big_endian
元素定义方式如下：
element <element name> <number in file>
property <data type> <property name 1>
property <data type> <property name 2>
property <data type> <property name 3>
...
其中对应的<data type>有：
| Name | Type |
|---|---|
| char | (8-bit) character |
| uchar | (8-bit) unsigned character |
| short | (16-bit) short integer |
| ushort | (16-bit) unsigned short integer |
| int | (32-bit) integer |
| uint | (32-bit) unsigned integer |
| float | (32-bit) single-precision float |
| double | (64-bit) double-precision float |
对于list的属性为：
property list <count data type> <data type> <property name>
在文件头里面还可以添加注释，具体格式如下：
comment <comment text>
Data
header之后存数据。按照之前约定的元素顺序和属性类型，依次存储。
Common Elements and Properties
常见元素和属性为：
| Required Core Property | Element | Property | Data Type | Property Description |
|---|---|---|---|---|
| ✓ | vertex | x | float |
x,y,z coordinates |
| ✓ | y | float |
||
| ✓ | z | float |
||
| nx | float |
x,y,z of normal | ||
| ny | float |
|||
| nz | float |
|||
| red | uchar |
vertex color | ||
| green | uchar |
|||
| blue | uchar |
|||
| alpha | uchar |
amount of transparency | ||
| material_index | int |
index to list of materials | ||
| face | vertex_indices | list of int | indices to vertices | |
| back_red | uchar |
backside color | ||
| back_green | uchar |
|||
| back_blue | uchar |
|||
| edge | vertex1 | int |
index to vertex | |
| vertex2 | int |
index to other vertex | ||
| crease_tag | uchar |
crease in subdivision surface | ||
| material | red | uchar |
material color | |
| green | uchar |
|||
| blue | uchar |
|||
| alpha | uchar |
amount of transparency | ||
| reflect_coeff | float |
amount of light reflected | ||
| refract_coeff | float |
amount of light refracted | ||
| refract_index | float |
index of refraction | ||
| extinct_coeff | float |
extinction coefficent |
Unity Ply Reader
附上项目路径：https://github.com/grassofsky/PlyImporter
PlyImporter
原始项目的说明见：https://github.com/3DBear/PlyImporter
在原来基础上的改动主要有
- 增加了PlyElement基类，专门用来处理不同的element，方便后期进行扩展，目前支持PlyFaceElement，PlyVertexElement；
- 增加了PlyProperty基类，处理不同的属性，按照属性的功能又分为PlyMultiProperty，用来支持单个property定义；PlyListProperty支持property list定义。
TODO
- 支持PlyEdgeElement；
- 考虑到Unity中的shader基本没有用到顶点的颜色，增加PlyMaterialElement用来设定材质颜色；
- 通常对于加载的文件，需要知道该文件对应的网格名称，扩展comment支持更多的选项；
- Support for Binary Big Endian
- PLY exporting