Minimal Vertex Shader Setup

This example demonstrates how to set up a basic vertex shader. Please refer to the source code (linked below) to see how it is tied into the IndigoShader entry point, which is a cut down version of the other entry point types, and holds clues as to how you'll need to integrate your shader into a real game.

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How to set up a minimal vertex shader

Inside a custom shader object we define an ultraviolet shader. To do that, we need to supply a ShaderId, that we'll need to register in Indigo's boot data, and also the vertex and fragment shaders themselves.

We import the ultraviolet syntax inside the object in order to avoid import collisions.

The vertex shader presented here is a 'no-op', it simply returns the vertex position as is, without modification. However we could use this function to affect the position of the vertex or values such as the UV coordinates. We could also do calculations and pass the results across to the fragment shader via 'varying' values.

The fragment shader is a simple function that maps the UV coordinates to the red and green channels, just so that we can see the effect of the shader.

object CustomShader:

  val shader: Shader =
    UltravioletShader(
      ShaderId("shader"),
      EntityShader.vertex[VertexEnv](vertex, VertexEnv.reference),
      EntityShader.fragment[FragmentEnv](fragment, FragmentEnv.reference)
    )

  import ultraviolet.syntax.*

  inline def vertex: Shader[VertexEnv, Unit] =
    Shader[VertexEnv] { env =>
      def vertex(v: vec4): vec4 =
        v
    }

  inline def fragment: Shader[FragmentEnv, Unit] =
    Shader[FragmentEnv] { env =>
      def fragment(color: vec4): vec4 =
        vec4(env.UV, 0.0f, 1.0f)
    }