How to use custom shader?

Graphics
#1

This may seem silly, but I can’t figure out how to use a custom shader. The documentation seems to be sorely lacking information, or flat out wrong. I have been working to have a simple custom shader that outputs the solid color red for five days now, without any luck.

Here are the steps I took:
1) In GameStudio, select Add asset --> Materials --> Material (empty)

You can’t write any custom shader code. You can only manpulate the material settings which magically auto-generate a shader.

2) Following this page
http://doc.xenko.com/1.10/manual/graphics/effects-and-shaders/shading-language/automatic-shader-stage-input-output.html
In VisualStudio, I created a super simple .xksl file with this code:

class Color : ShaderBase
{
    stream float4 pos : POSITION;
    stream float4 col : COLOR;

    override void VSMain()
    {
        streams.ShadingPosition = streams.pos;
    }

    override void PSMain()
    {
        streams.ColorTarget = float4(1, 0, 0, 1);
    }
};

This successfully “compiled” and created the corresponding .cs file and the “Effect Shader” asset appears in the Asset view of GameStudio. But I have no idea how I can apply it to a mesh or generate a Material from it. There seems to be no options inside GameStudio for the asset and I can’t find anything in the API to apply a shader to a mesh. So, I figured I had to create an Effect to use the custom shader.

3) Following this page
http://doc.xenko.com/1.10/manual/graphics/effects-and-shaders/effect-language.html
In VisualStudio, I created an .xkfx file with the contents of BasicEffect. However, the .cs file generated by Xenko is invalid as it references the namespace SiliconStudio.Xenko.Effects.Data which doesn’t exist. I had to manually edit the auto-generated code to get it to compile (which is explictly says NOT to do).

4) Following this page
http://doc.xenko.com/1.10/manual/graphics/effects-and-shaders/index.html

I created a C# script and when I tried to load the effect by calling
var myEffect = EffectSystem.LoadEffect("BasicEffect").WaitForResult();
I got an AggregateException.

Confusingly, when I tried loading my .xksl file (Color.xksl), it worked.
var myEffect = EffectSystem.LoadEffect("Color").WaitForResult();

But the documentation then says I need to bind it to the pipeline and points to this page
http://doc.xenko.com/1.10/manual/graphics/low-level-api/pipeline-state.html

The very first code example says to do this to create the pipeline state

var pipelineStateDescription = new PipelineStateDescription();
var pipelineState = PipelineState.New(GraphicsDevice, ref pipelineStateDescription);

But this causes a SharpDX exception to be thrown.

Is there no way to write your own shader from scratch in Xenko?

#2

I agree, the available documentation/information about shaders/effects/materials is quite laking. There are 2 samples for shaders “Custom Effect Sample” and “Custom Material Shader” they might be more helpful.

#3

Thanks. I had looked at the “Custom Material Shader” sample and found it quite… awkward. A material asset with hard-coded strings that are IDs for “shaders” that have Compute() methods that are called in vertex shaders or pixel shaders, depending upon which field the string ID was entered on. Bleh!

I had somehow missed the “Custom Effect Sample”, so thanks for that. That’s much closer to what I’m trying to accomplish. Unfortunately it uses a sprite instead of a mesh/model, so I don’t know how much more work it takes to have a custom shader on a model. I do think it’s crazy how much low-level setup needs to be done for the sample. I was expecting a higher level solution in an actual game engine. This is barely above direct DirectX/OpenGL API calls.