Custom shaders
- Create a shader
Use a custom shader
- Tip
- Note
Arguments and parameters
- Template arguments
- Parameters
  - Note
Compositions
Custom shader sample
See also

Custom shaders

IntermediateProgrammer

You can write your own shaders in Visual Studio and use them in material attributes. For example, you can write a shader to add textures to materials based on the objects' world positions, or generate noise and use it to randomize material properties.

As shaders are text files, you can add comments, enable and disable lines of code, and edit them like any other code file. This makes them easy to maintain and iterate.

You can also use custom shaders to create custom post effects. For more information, see Custom color transforms.

Create a shader

Make sure you have the Xenko Visual Studio extension installed. This is necessary to convert the shader files from XSL (Xenko shading language) to .cs files.
In Game Studio, in the toolbar, click (Open in IDE) to open your project in Visual Studio.
In the Visual Studio Solution Explorer, right-click the project (eg MyGame.Game) and select Add > New item.

Select Class.

In the Name field, specify a name with the extension .xksl (eg MyShader.xksl), and click Add.

The Xenko Visual Studio extension automatically generates a .cs file from the .xksl file. The Solution Explorer lists it as a child of the .xskl file.

Open the .xksl file, remove the existing lines, and write your shader.

Shaders are written in Xenko Shading Language (XSL), which is based on HLSL. For more information, see Shading language.

For example, this shader creates a green color (RGBA 0;1;0;1):

namespace MyGame
{
    shader MyShader : ComputeColor
    {
        override float4 Compute()
        {
            return float4(0, 1, 0, 1);
        }
    };
}

Note

Make sure the shader name in the file (eg MyShader above) is the same as the filename.

Note

To be accessible from the Game Studio Property Grid, the shader must inherit from ComputeColor.As 'ComputeColor always returns a float4 value, properties that take float values (eg metalness and gloss maps) use the first component (the red component) of the value returned by ComputeColor.

Save all the files in the solution (File > Save All).
In Game Studio, reload the assemblies.

The Asset View lists the shader in the same directory as your scripts (eg MyGame.Game).

Note

In some situations, Game Studio incorrectly identifies the shader as a script, as in the screenshot below:

If this happens, restart Game Studio (File > Reload project).

Use a custom shader

You can use custom shaders in any material attribute.

In the Asset View, select the material you want to use the shader in.
In the Property Grid, next to the property you want to control with the shader, click (Change) and select Shader.

In the field, type the name of your shader (eg MyShader).

The property uses the shader you specify.

Tip

When you make a change to the .xksl file in Visual Studio and save it, Game Studio automatically updates the project with your changes. If this doesn't happen, restart Game Studio (File > Reload project).

Note

If you delete a shader from the project assets, to prevent errors, make sure you also remove it from the properties of materials that use it.

Arguments and parameters

Template arguments

Template arguments (generics) don't change at runtime. However, different materials can use different instances of the shader with different values.

When the shaders are compiled, Xenko substitutes template arguments with the value you set in the Property Grid.

For example, the code below defines and uses the template argument Frequency:

shader ComputeColorWave<float Frequency> : ComputeColor, Texturing
{
    override float4 Compute()
   {           
        return sin((Global.Time) * 2 * 3.14 * Frequency);
    }
};

Parameters

Parameters can be changed at runtime.

For example, the code below defines and uses the dynamic parameter Frequency:

shader ComputeColorWave: ComputeColor, Texturing
{
    stage float Frequency = 1.0f;
    override float4 Compute()
    {
        return sin(( Global.Time ) * 2 * 3.14 * Frequency);
    }
};

To modify the value at runtime, access and set it in the material parameter collection. For example, to change the Frequency, use:

myMaterial.Passes[myPassIndex].Parameters.Set(ComputeColorWaveKeys.Frequency, MyFrequency);

Note

ComputeColorWaveKeys.Frequency is generated by the Xenko Visual Studio extension from the shader file.

Compositions

This composition lets you set the Frequency in the Game Studio Property Grid:

shader ComputeColorWave : ComputeColor, Texturing
{
    compose ComputeColor Frequency;
    override float4 Compute()
    {
        return sin(( Global.Time ) * 2 * 3.14 * Frequency.Compute().r);
    }
};