For Cg/HLSL vertex programs, the
MeshThe main graphics primitive of Unity. Meshes make up a large part of your 3D worlds. Unity supports triangulated or Quadrangulated polygon meshes. Nurbs, Nurms, Subdiv surfaces must be converted to polygons. More info
See in Glossary vertex data is passed as inputs to the vertex
shader function. Each input needs to have a semantic specified for it: for example, POSITION
input is the vertex position, and NORMAL
is the vertex normal.
Often, vertex data inputs are declared in a structure, instead of listing them one by one.
Several commonly used vertex structures are defined in UnityCG.cginc include file, and in most cases it’s enough just to use those. The structures are:
appdata_base
: position, normal and one texture coordinate.appdata_tan
: position, tangent, normal and one texture coordinate.appdata_full
: position, tangent, normal, four texture coordinates and color.appdata_img
: vertex shaderA program that runs on the GPU. More infoThis shader colors the mesh based on its normals, and uses appdata_base
as vertex program input:
Shader "VertexInputSimple" { SubShader { Pass { CGPROGRAM #pragma vertex vert #pragma fragment frag #include "UnityCG.cginc" struct v2f { float4 pos : SV_POSITION; fixed4 color : COLOR; }; v2f vert (appdata_base v) { v2f o; o.pos = UnityObjectToClipPos(v.vertex); o.color.xyz = v.normal * 0.5 + 0.5; o.color.w = 1.0; return o; } fixed4 frag (v2f i) : SV_Target { return i.color; } ENDCG } } }
To access different vertex data, you need to declare the vertex structure yourself, or add input parameters to the vertex shader. Vertex data is identified by Cg/HLSL semantics, and must be from the following list:
POSITION
is the vertex position, typically a float3
or float4
.NORMAL
is the vertex normal, typically a float3
.TEXCOORD0
is the first UV coordinate, typically float2
, float3
or float4
.TEXCOORD1
, TEXCOORD2
and TEXCOORD3
are the 2nd, 3rd and 4th UV coordinates, respectively.TANGENT
is the tangent vector (used for normal mapping), typically a float4
.COLOR
is the per-vertex color, typically a float4
.When the mesh data contains fewer components than are needed by the vertex
shader input, the rest are filled with zeroes, except for the .w
component which defaults to 1. For example, mesh texture coordinates
are often 2D vectors with just x and y components. If a vertex
shader declares a float4
input with TEXCOORD0
semantic, the
value received by the vertex shaderA program that runs on each vertex of a 3D model when the model is being rendered. More info
See in Glossary will contain (x,y,0,1).
For best cross platform support, label vertex outputs and fragment inputs as TEXCOORDn
semantics.
Unity also supports the following:
VPOS
- the position of the pixelThe smallest unit in a computer image. Pixel size depends on your screen resolution. Pixel lighting is calculated at every screen pixel. More info#pragma target 3.0
compilation directive, and should output the clip space position as a separate “out” variable. For maximum portability use the UNITY_VPOS_TYPE
type for it, which is float4
on most platforms.VFACE
- whether the rendered surface is facing the cameraA component which creates an image of a particular viewpoint in your scene. The output is either drawn to the screen or captured as a texture. More info#pragma target 3.0
compilation directive.SV_VertexID
- the index of the vertex being processed. The shader must have a #pragma target 3.5
compilation directive.For examples of using these techniques to visualize vertex data in the Built-in Render PipelineA series of operations that take the contents of a Scene, and displays them on a screen. Unity lets you choose from pre-built render pipelines, or write your own. More info
See in Glossary, see Visualizing vertex data.
Direct3D 11 groups all Shader variables into “constant buffers”. Most of Unity’s built-in variables are already grouped, but for variables in your own Shaders it might be more optimal to put them into separate constant buffers depending on expected frequency of updates.
Use CBUFFER_START(name)
and CBUFFER_END
macros for that:
CBUFFER_START(MyRarelyUpdatedVariables) float4 _SomeGlobalValue; CBUFFER_END
If you use a GPU compute buffer or graphics buffer to set the value of the variables, make sure the buffer and the constant buffer have matching data layouts on all graphics APIs you build for. See Using constant buffers with GPU buffers for more information.
Note: You can’t add structs to constant buffers.
There are limits to how many interpolator variables can be used in total to pass the information from the vertex into the fragment shader. The limit depends on the platform and GPU, and the general guidelines are:
float4
variable (.xy for one coordinate, .zw
for the second coordinate).#pragma target 3.0
).#pragma target 4.0
).Regardless of your particular target hardware, it’s generally a good idea to use as few interpolators as possible for performance reasons.
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