FadeIn Scene Program and Material

fadeIn.swift

func addFadeInMaterialToChild(child:SCNNode) {
  
  let program = SCNProgram()
  program.fragmentFunctionName = "fadeInSurfaceFragment"
  program.vertexFunctionName = "fadeInVertexShader"
  program.isOpaque = false;
            
  // CREATE A MATERIAL, ADD THE PROGRAM, AND ADD IT TO THE CHILD.
  let shaderMaterial = SCNMaterial()
  shaderMaterial.program = program;
  shaderMaterial.transparencyMode = .rgbZero;
  shaderMaterial.blendMode = .alpha;
  shaderMaterial.writesToDepthBuffer = false
  shaderMaterial.readsFromDepthBuffer = false
  shaderMaterial.cullMode = .back
  child.geometry?.materials.removeAll();
  child.geometry?.materials = [shaderMaterial];
  
}