PhongShader.cs

using Waher.Runtime.Collections;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Model;
using Waher.Script.Objects;
 
namespace Waher.Script.Graphs3D.Functions.Shading
{
    public class PhongShader : FunctionMultiVariate
    {
        public PhongShader(ScriptNode Diffuse, ScriptNode Specular, ScriptNode Position, 
            int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { Diffuse, Specular, Position }, 
                  new ArgumentType[] { ArgumentType.Scalar, ArgumentType.Scalar, ArgumentType.Normal }, Start, Length, Expression)
        {
        }
 
        public override string FunctionName => nameof(PhongShader);
 
        public override string[] DefaultArgumentNames => new string[]
        {
            "Material",
            "Ambient",
            "LightSources"
        };
 
        public override IElement Evaluate(IElement[] Arguments, Variables Variables)
        {
            Graphs3D.PhongIntensity Ambient = Graphs3D.Canvas3D.ToPhongIntensity(Arguments[1].AssociatedObjectValue);
            Graphs3D.PhongLightSource[] LightSources;
            object Obj;
 
            if (!(Arguments[0].AssociatedObjectValue is Graphs3D.PhongMaterial Material))
                throw new ScriptRuntimeException("Phong material expected in first argument.", this);
 
            Obj = Arguments[2].AssociatedObjectValue;
            if (Obj is Graphs3D.PhongLightSource Source)
                LightSources = new Graphs3D.PhongLightSource[] { Source };
            else if (Obj is IVector V)
            {
                ChunkedList<Graphs3D.PhongLightSource> Sources = new ChunkedList<Graphs3D.PhongLightSource>();
 
                foreach (IElement E in V.VectorElements)
                {
                    if (E.AssociatedObjectValue is Graphs3D.PhongLightSource Source2)
                        Sources.Add(Source2);
                    else
                        throw new ScriptRuntimeException("Expected one or more light sources for the third argument.", this);
                }
 
                LightSources = Sources.ToArray();
            }
            else
                throw new ScriptRuntimeException("Expected one or more light sources for the third argument.", this);
 
            return new ObjectValue(new Graphs3D.PhongShader(Material, Ambient, LightSources));
        }
    }
}