此类描述子着色器的通道。
| IsGrabPass | Indicates whether this Pass results from a GrabPass command. |
| Name | 此通道的名称（可能为空）。 |
| SourceCode | 此通道的源代码。 |
| CompileVariant | Compiles a shader variant for this shader pass and returns its bytecode and resource layout. |
| FindTagValue | Searches for the tag specified by tagName on this SubShader and returns the value of the tag. |
| HasShaderStage | Checks whether this pass includes a shader stage. |
| PreprocessVariant | Preprocesses a shader variant for this shader pass and returns the preprocessed code. |