文档

Unity Engine

User Manual

Script Reference

Unity Engine

Input data into HLSL

Create a struct that declares shader variables and connects them to the vertex data of the mesh.
阅读时间2 分钟最后更新于 22 天前
重要
The Built-In Render Pipeline is deprecated and will be made obsolete in a future release.
It remains supported, including bug fixes and maintenance, through the full Unity 6.7 LTS lifecycle.
For more information on migration, refer to Migrating from the Built-In Render Pipeline to the Universal Render Pipeline and Render pipeline feature comparison.
To pass data into a custom shader in High-Level Shader Language (HLSL), create a 
struct
that declares shader variables and connects them to the mesh vertex data.
Use one of the following methods:
  • Include a prebuilt vertex structure from Unity's shader library.
  • Declare a custom vertex structure.

Include a prebuilt structure

Unity has a library of High-Level Shader Language (HLSL) shader files that contain prebuilt HLSL structures with common vertex inputs. For more information, refer to:

Declare a custom structure

To declare a custom vertex structure, follow these steps:
  1. At the top of your 
    HLSLPROGRAM
    , add a 
    struct
    that declares a variable for each input you want to access from the mesh.
  2. In each variable declaration, add a semantic that connects the variable to the mesh data. For more information about semantics, refer to Semantics in the Microsoft HLSL documentation.
For a list of semantics, refer to HLSL semantics reference.
For example:
Shader "VertexInputCustom" {	SubShader {		Pass {			HLSLPROGRAM			...			struct custom_vertex_input {				// Declare a variable for the vertex position, and connect it to the mesh data using the POSITION semantic.				float4 vertex : POSITION;				// Declare a variable for the vertex normal, and connect it to the mesh data using the NORMAL semantic.				float3 normal : NORMAL;			};			...			v2f vert (custom_vertex_input v) {				...			}			ENDHLSL		}	}}
If a variable contains more components than the mesh data, the extra components are 0 for x, y, and z, and 1 for w. For example, if you declare a 
float4
with 
TEXCOORD0
, the value is (u, v, 0, 1).

Passing data from the vertex shader to the fragment shader

The data you pass from the vertex shader to the fragment shader, known as interpolators, has limits based on the target platform and GPU.
To minimize the number of interpolators you use, pack data into single variables. For example, combine two sets of 
float2
UV coordinates into one 
float4
variable, where x and y contain the first UV coordinate and z and w contain the second UV coordinate.

Add a custom buffer for uniform variables

DirectX groups all uniform variables into constant buffers. Rendering might be faster if you group uniform variables into separate constant buffers depending on how often they change.
To create a constant buffer, use the 
CBUFFER_START
and 
CBUFFER_END
Unity macros. For example:
CBUFFER_START(RarelyUpdatedVariables)	float4 lightPosition;CBUFFER_ENDCBUFFER_START(FrequentlyUpdatedVariables)	float4 colorTint;CBUFFER_END

Additional resources