From c475e83aa3910756a9e7f78a04fded1fead78bb4 Mon Sep 17 00:00:00 2001
From: "W2.Wizard" <leon.delahamette@hotmail.de>
Date: Sat, 20 Feb 2021 15:44:06 +0100
Subject: [PATCH] Added RGBToHSV

---
 Source/Editor/Surface/Archetypes/Material.cs  | 19 +++++++++++++-
 .../MaterialGenerator.Material.cpp            | 25 ++++++++++++++-----
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/Source/Editor/Surface/Archetypes/Material.cs b/Source/Editor/Surface/Archetypes/Material.cs
index 1c679a039..2b3bb4703 100644
--- a/Source/Editor/Surface/Archetypes/Material.cs
+++ b/Source/Editor/Surface/Archetypes/Material.cs
@@ -819,7 +819,7 @@ namespace FlaxEditor.Surface.Archetypes
             {
                 TypeID = 36,
                 Title = "HSVToRGB",
-                Description = "Converts a HSV value to linear RGB",
+                Description = "Converts a HSV value to linear RGB [X = 0/360, Y = 0/1, Z = 0/1]",
                 Flags = NodeFlags.MaterialGraph,
                 Size = new Vector2(160, 25),
                 DefaultValues = new object[]
@@ -831,6 +831,23 @@ namespace FlaxEditor.Surface.Archetypes
                     NodeElementArchetype.Factory.Input(0, "HSV", true, typeof(Vector3), 0, 0),
                     NodeElementArchetype.Factory.Output(0, "RGB", typeof(Vector3), 1),
                 }
+            },
+            new NodeArchetype
+            {
+                TypeID = 37,
+                Title = "RGBToHSV",
+                Description = "Converts a linear RGB value to HSV [X = 0/360, Y = 0/1, Z = 0/1]",
+                Flags = NodeFlags.MaterialGraph,
+                Size = new Vector2(160, 25),
+                DefaultValues = new object[]
+                {
+                    new Vector3(0, 1, 0),
+                },
+                Elements = new[]
+                {
+                    NodeElementArchetype.Factory.Input(0, "RGB", true, typeof(Vector3), 0, 0),
+                    NodeElementArchetype.Factory.Output(0, "HSV", typeof(Vector3), 1),
+                }
             }
         };
     }
diff --git a/Source/Engine/Tools/MaterialGenerator/MaterialGenerator.Material.cpp b/Source/Engine/Tools/MaterialGenerator/MaterialGenerator.Material.cpp
index 2abae3622..4866b3483 100644
--- a/Source/Engine/Tools/MaterialGenerator/MaterialGenerator.Material.cpp
+++ b/Source/Engine/Tools/MaterialGenerator/MaterialGenerator.Material.cpp
@@ -463,15 +463,28 @@ void MaterialGenerator::ProcessGroupMaterial(Box* box, Node* node, Value& value)
     {
         const auto hsv = tryGetValue(node->GetBox(0), node->Values[0]).AsVector3();
 
-        // Normalize
-        auto color = writeLocal(ValueType::Vector3, String::Format(TEXT("float3({0}.x / 360, {0}.y, {0}.z)"), hsv.Value), node);
+        // Normalize from 360
+        auto color = writeLocal(ValueType::Vector3, String::Format(TEXT("float3({0}.x / 360.0f, {0}.y, {0}.z)"), hsv.Value), node);
 
         auto x1 = writeLocal(ValueType::Vector3, String::Format(TEXT("clamp(abs(fmod({0}.x * 6.0 + float3(0.0f, 4.0f, 2.0f), 6.0f) - 3.0f) - 1.0f, 0.0f, 1.0f)"), color.Value), node);
-        
-        // Smooth out
-        auto x2 = writeLocal(ValueType::Vector3, String::Format(TEXT("{0} * {0} * (3.0 - 2.0 * {0})"), x1.Value), node);
-        value = writeLocal(ValueType::Vector3, String::Format(TEXT("{1}.z * lerp(float3(1.0, 1.0, 1.0), {0}, {1}.y)"), x2.Value, color.Value), node);
+        value = writeLocal(ValueType::Vector3, String::Format(TEXT("{1}.z * lerp(float3(1.0, 1.0, 1.0), {0}, {1}.y)"), x1.Value, color.Value), node);
+        break;
+    }
+        // RGBToHSV
+    case 37:
+    {
+        // Reference: Ian Taylor, https://www.chilliant.com/rgb2hsv.html
 
+        const auto rgb = tryGetValue(node->GetBox(0), node->Values[0]).AsVector3();
+        const auto epsilon = writeLocal(ValueType::Float, TEXT("1e-10"), node);
+
+        auto p = writeLocal(ValueType::Vector4, String::Format(TEXT("({0}.g < {0}.b) ? float4({0}.bg, -1.0f, 2.0f/3.0f) : float4({0}.gb, 0.0f, -1.0f/3.0f)"), rgb.Value), node);
+        auto q = writeLocal(ValueType::Vector4, String::Format(TEXT("({0}.r < {1}.x) ? float4({1}.xyw, {0}.r) : float4({0}.r, {1}.yzx)"), rgb.Value, p.Value), node);
+        auto c = writeLocal(ValueType::Float, String::Format(TEXT("{0}.x - min({0}.w, {0}.y)"), q.Value), node);
+        auto h = writeLocal(ValueType::Float , String::Format(TEXT("abs(({0}.w - {0}.y) / (6 * {1} + {2}) + {0}.z)"), q.Value, c.Value, epsilon.Value), node);
+        
+        auto hcv = writeLocal(ValueType::Vector3, String::Format(TEXT("float3({0}, {1}, {2}.x)"), h.Value, c.Value, q.Value), node);
+        value = writeLocal(ValueType::Vector3, String::Format(TEXT("float3({0}.x * 360.0f, {0}.y / ({0}.z + {1}), {0}.z)"), hcv.Value, epsilon.Value), node);
         break;
     }
     default: