ScriptableRenderPipeline/com.unity.shadergraph/Editor/Data/Nodes/Input/Texture/SampleTexture2DLODNode.cs

using System.Linq;
using UnityEngine;
using UnityEditor.Graphing;
using UnityEditor.ShaderGraph.Drawing.Controls;

namespace UnityEditor.ShaderGraph
{
    
    [Title("Input", "Texture", "Sample Texture 2D LOD")]
    public class SampleTexture2DLODNode : AbstractMaterialNode, IGeneratesBodyCode, IMayRequireMeshUV
    {
        public const int OutputSlotRGBAId = 0;
        public const int OutputSlotRId = 5;
        public const int OutputSlotGId = 6;
        public const int OutputSlotBId = 7;
        public const int OutputSlotAId = 8;
        public const int TextureInputId = 1;
        public const int UVInput = 2;
        public const int SamplerInput = 3;
        public const int LODInput = 4;

        const string kOutputSlotRGBAName = "RGBA";
        const string kOutputSlotRName = "R";
        const string kOutputSlotGName = "G";
        const string kOutputSlotBName = "B";
        const string kOutputSlotAName = "A";
        const string kTextureInputName = "Texture";
        const string kUVInputName = "UV";
        const string kSamplerInputName = "Sampler";
        const string kLODInputName = "LOD";

        public override bool hasPreview { get { return true; } }

        public SampleTexture2DLODNode()
        {
            name = "Sample Texture 2D LOD";
            UpdateNodeAfterDeserialization();
        }

        public override string documentationURL
        {
            get { return "https://github.com/Unity-Technologies/ShaderGraph/wiki/Sample-Texture-2D-LOD-Node"; }
        }

        [SerializeField]
        private TextureType m_TextureType = TextureType.Default;

        [EnumControl("Type")]
        public TextureType textureType
        {
            get { return m_TextureType; }
            set
            {
                if (m_TextureType == value)
                    return;

                m_TextureType = value;
                Dirty(ModificationScope.Graph);
            }
        }

        public sealed override void UpdateNodeAfterDeserialization()
        {
            AddSlot(new Vector4MaterialSlot(OutputSlotRGBAId, kOutputSlotRGBAName, kOutputSlotRGBAName, SlotType.Output, Vector4.zero, ShaderStageCapability.All));
            AddSlot(new Vector1MaterialSlot(OutputSlotRId, kOutputSlotRName, kOutputSlotRName, SlotType.Output, 0, ShaderStageCapability.All));
            AddSlot(new Vector1MaterialSlot(OutputSlotGId, kOutputSlotGName, kOutputSlotGName, SlotType.Output, 0, ShaderStageCapability.All));
            AddSlot(new Vector1MaterialSlot(OutputSlotBId, kOutputSlotBName, kOutputSlotBName, SlotType.Output, 0, ShaderStageCapability.All));
            AddSlot(new Vector1MaterialSlot(OutputSlotAId, kOutputSlotAName, kOutputSlotAName, SlotType.Output, 0, ShaderStageCapability.All));
            AddSlot(new Texture2DInputMaterialSlot(TextureInputId, kTextureInputName, kTextureInputName));
            AddSlot(new UVMaterialSlot(UVInput, kUVInputName, kUVInputName, UVChannel.UV0));
            AddSlot(new SamplerStateMaterialSlot(SamplerInput, kSamplerInputName, kSamplerInputName, SlotType.Input));
            AddSlot(new Vector1MaterialSlot(LODInput, kLODInputName, kLODInputName, SlotType.Input, 0));
            RemoveSlotsNameNotMatching(new[] { OutputSlotRGBAId, OutputSlotRId, OutputSlotGId, OutputSlotBId, OutputSlotAId, TextureInputId, UVInput, SamplerInput, LODInput });
        }

        // Node generations
        public virtual void GenerateNodeCode(ShaderGenerator visitor, GenerationMode generationMode)
        {
            var uvName = GetSlotValue(UVInput, generationMode);

            //Sampler input slot
            var samplerSlot = FindInputSlot<MaterialSlot>(SamplerInput);
            var edgesSampler = owner.GetEdges(samplerSlot.slotReference);

            var lodSlot = GetSlotValue(LODInput, generationMode);

            var id = GetSlotValue(TextureInputId, generationMode);
            
            var result = string.Format("{0}4 {1} = SAMPLE_TEXTURE2D_LOD({2}, {3}, {4}, {5});"
                    , precision
                    , GetVariableNameForSlot(OutputSlotRGBAId)
                    , id
                    , edgesSampler.Any() ? GetSlotValue(SamplerInput, generationMode) : "sampler" + id
                    , uvName
                    , lodSlot);

            visitor.AddShaderChunk(result, true);

            if (textureType == TextureType.Normal)
                visitor.AddShaderChunk(string.Format("{0}.rgb = UnpackNormalmapRGorAG({0});", GetVariableNameForSlot(OutputSlotRGBAId)), true);

            visitor.AddShaderChunk(string.Format("{0} {1} = {2}.r;", precision, GetVariableNameForSlot(OutputSlotRId), GetVariableNameForSlot(OutputSlotRGBAId)), true);
            visitor.AddShaderChunk(string.Format("{0} {1} = {2}.g;", precision, GetVariableNameForSlot(OutputSlotGId), GetVariableNameForSlot(OutputSlotRGBAId)), true);
            visitor.AddShaderChunk(string.Format("{0} {1} = {2}.b;", precision, GetVariableNameForSlot(OutputSlotBId), GetVariableNameForSlot(OutputSlotRGBAId)), true);
            visitor.AddShaderChunk(string.Format("{0} {1} = {2}.a;", precision, GetVariableNameForSlot(OutputSlotAId), GetVariableNameForSlot(OutputSlotRGBAId)), true);
        }

        public bool RequiresMeshUV(UVChannel channel, ShaderStageCapability stageCapability)
        {
            s_TempSlots.Clear();
            GetInputSlots(s_TempSlots);
            foreach (var slot in s_TempSlots)
            {
                if (slot.RequiresMeshUV(channel))
                    return true;
            }
            return false;
        }
    }
}