Mixing channels

[ralfox]

Is there any guidance on how to mix color channels, e.g., to make false color renderings.

Presumably this can be implemented with a fragment shader.

How to add an extra layer, being the combination of multiple channels?

[ralfox]

Step one may be to add a new layer to src/layers/viv-layers.ts, injecting a shader:

// Writing deck.gl shaders: https://deck.gl/docs/developer-guide/custom-layers/writing-shaders

export class FalseColorLayer extends MultiscaleImageLayer {
  getShaders() {
    const shaders = super.getShaders();
    return {
      ...shaders,
      inject: {
        'fs:#decl': `
          uniform sampler2D uTexture0;
          uniform sampler2D uTexture1;
        `,
        'fs:DECKGL_FILTER_COLOR': `
          vec4 red = texture2D(uTexture0, geometry.uv);
          vec4 green = texture2D(uTexture1, geometry.uv);
          color = vec4(red.r, green.r, 0.0, 1.0);
        `
      },
      modules: [project32]
    };
  }
}

How can such a layer be added to the view?

[will-moore]

I had a draft PR a while back that experimented with adding a Layer. Don't know if it's any help now; code might have changed a bit since then:

#128