Shader Reference

<cat>Material.ShaderReference</cat>
<title>Shader Reference</title>

# Global Variables
These variables can be called anywhere in the global namespace.


|Data Type|Name|Description|
|-----|----------|
|float|g_flTime|Current time|
|float|g_flViewportMinZ|Near clip plane|
|float|g_flViewportMaxZ|Far clip plane|
|float2|g_vViewportSize|Viewport size in pixels|
|float2|g_vInvViewportSize|1 divided by g_vViewportSize|
|float2|g_vViewportOffset|The offset of the viewport in pixels|
|float2|g_vRenderTargetSize|The absolute size of the current render target|
|float3|g_vCameraPositionWs|Camera position in world space|
|float3|g_vCameraDirWs|Camera direction in world space|
|float4x4|g_matViewToProjection||
|float4x4|g_matWorldToView||
|float4x4|g_matProjectionToWorld||
|float4x4|g_matWorldToProjection||

# Variables

Variables will show up in Material Editor. They're defined like this.

```
float3 g_vColorTint < UiType( Color ); Default3( 1.0, 1.0, 1.0 ); UiGroup( "Color,10/20" ); >;
float2 g_vTexCoordScale < UiType( Slider ); UiStep( 1 ); Default2( 1.0, 1.0 ); UiGroup( "Texture Coordinates,10/21" ); >;
Float3Attribute( g_vColorTint, g_vColorTint ); // Only needed if your variable is not showing up in the material editor
Float2Attribute( g_vTexCoordScale, g_vTexCoordScale);
```

A list of attributes you can expose can be seen below

| Data Type | Attribute Function |
|-----------|--------------------|
| bool | BoolAttribute |
| int/uint | IntAttribute |
| float | FloatAttribute |
| float2 | Float2Attribute |
| float3 | Float3Attribute |
| float4 | Float4Attribute |
| float/float2/float3/float4 | TextureAttribute |


## UiType

Describes how the variable should be represented in the editor.

|Name|Description|
|-----|----------|
|	VectorText	| Text boxes and sliders (this is the default) |
|	Slider		| A slider type. Usually combined with a Range setting. |
|	Color		| A Color picker, works on float3 or float4. |
|   Texture     | A texture picker |
|	CheckBox	| On or off, generally used on bool |

## UiStep

`UiStep` lets you set the amount of each interval or step that the value increases or decreases by.

## Default

The `Default` lets you specify the default value for the variable. If you're filling a `float2`, it should be `Default2`, if you're filling a `float4` it should be `Default4` etc.

## Range
The `Range` lets you cap the variable to a specific range. If you're filling a `float2`, it should be `Range2`, if you're filling a `float4` it should be `Range4` etc.

```
float g_flAlphaTestReference < Range(0.01, 0.99); UiType(Slider); >;
float2 g_vTexCoordScrollSpeed < Range2(-10, -10, 10, 10); UiType(VectorText); >;
```

## UiGroup

The `UiGroup` is used to sort the variable into a group, subgroup and define its order. So for example, given this..

```
float4 BorderColorL < UiType( Color ); Default4( 0.0, 0.0, 0.0, 1.0 ); UiGroup( "Border,10/Colors,10/1" ); >;
float4 BorderColorT < UiType( Color ); Default4( 0.0, 0.0, 0.0, 1.0 ); UiGroup( "Border,10/Colors,10/2" ); >;
float4 BorderColorR < UiType( Color ); Default4( 0.0, 0.0, 0.0, 1.0 ); UiGroup( "Border,10/Colors,10/3" ); >;
float4 BorderColorB < UiType( Color ); Default4( 0.0, 0.0, 0.0, 1.0 ); UiGroup( "Border,10/Colors,10/4" ); >;
```

You end up with this

<upload src="1/8d89e07e3fc960b.png" size="16898" name="image.png" />

The format is:

```
Heading,Order / Group,Order / VariableOrder
```


## Expression

`Expression` is used to evaluate an expression on the variable, using the [Dynamic Expressions](Using_Dynamic_Expressions) language.  A good reason for their use is to save GPU instructions, since they get evaluated on the CPU prior to rendering.

The expression can refer to: the variable itself with `this`, as well as to any other variables or features.

```
float3 g_vColorTint 		< Default3(1, 1, 1); UiType(Color); Expression(SrgbGammaToLinear(this)); >;

float4 g_vTexCoordXform 	< Expression(g_flTexCoordRotation*3.14159)/180); >;
int g_nFoliageAnimationMode < Expression(F_FOLIAGE_ANIMATION); >;
```

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