Start to work on actually rendering the node graph

14 files changed, 844 insertions, 358 deletions

diff --git a/.clang-format b/.clang-format
index c7e0c26..9f015c9 100644
--- a/.clang-format
+++ b/.clang-format
@@ -1,26 +1,13 @@
-# Commented out parameters are those with the same value as base LLVM style
-# We can uncomment them if we want to change their value, or enforce the
-# chosen value in case the base style changes (last sync: Clang 6.0.1).
----
-### General config, applies to all languages ###
-BasedOnStyle:  LLVM
+BasedOnStyle: LLVM
 AccessModifierOffset: -4
 AlignAfterOpenBracket: DontAlign
-# AlignConsecutiveAssignments: false
-# AlignConsecutiveDeclarations: false
-# AlignEscapedNewlines: Right
 AlignOperands: false
 AlignTrailingComments: false
 AllowAllParametersOfDeclarationOnNextLine: true
 AllowAllArgumentsOnNextLine: true
-# AllowShortBlocksOnASingleLine: false
 AllowShortCaseLabelsOnASingleLine: true
-AllowShortFunctionsOnASingleLine: Inline
+AllowShortFunctionsOnASingleLine: All
 AllowShortIfStatementsOnASingleLine: true
-# AllowShortLoopsOnASingleLine: false
-# AlwaysBreakAfterDefinitionReturnType: None
-# AlwaysBreakAfterReturnType: None
-# AlwaysBreakBeforeMultilineStrings: false
 AlwaysBreakTemplateDeclarations: MultiLine
 BinPackArguments: false
 BinPackParameters: false
@@ -40,87 +27,25 @@ BraceWrapping:
   SplitEmptyFunction: true
   SplitEmptyRecord: true
   SplitEmptyNamespace: true
-# BreakBeforeBinaryOperators: None
 BreakBeforeBraces: Custom
-# BreakBeforeInheritanceComma: false
 BreakBeforeTernaryOperators: true
 BreakConstructorInitializers: BeforeComma
-# BreakStringLiterals: true
-ColumnLimit:     0
-# CommentPragmas:  '^ IWYU pragma:'
-# CompactNamespaces: false
+ColumnLimit: 0
 ConstructorInitializerAllOnOneLineOrOnePerLine: true
 ConstructorInitializerIndentWidth: 4
 ContinuationIndentWidth: 4
 Cpp11BracedListStyle: false
-# DerivePointerAlignment: false
-# DisableFormat:   false
-# ExperimentalAutoDetectBinPacking: false
-# FixNamespaceComments: true
-# ForEachMacros:
-#   - foreach
-#   - Q_FOREACH
-#   - BOOST_FOREACH
-# IncludeBlocks:   Preserve
 IncludeCategories:
-  - Regex:           '".*"'
-    Priority:        1
-  - Regex:           '^<.*\.h>'
-    Priority:        2
-  - Regex:           '^<.*'
-    Priority:        3
-# IncludeIsMainRegex: '(Test)?$'
+  - Regex: '".*"'
+    Priority: 1
+  - Regex: '^<.*\.h>'
+    Priority: 2
+  - Regex: '^<.*'
+    Priority: 3
 IndentCaseLabels: true
 IndentPPDirectives: AfterHash
-IndentWidth:     4
-# IndentWrappedFunctionNames: false
-# JavaScriptQuotes: Leave
-# JavaScriptWrapImports: true
-# KeepEmptyLinesAtTheStartOfBlocks: true
-# MacroBlockBegin: ''
-# MacroBlockEnd:   ''
-# MaxEmptyLinesToKeep: 1
+IndentWidth: 4
 NamespaceIndentation: Inner
-# PenaltyBreakAssignment: 2
-# PenaltyBreakBeforeFirstCallParameter: 19
-# PenaltyBreakComment: 300
-# PenaltyBreakFirstLessLess: 120
-# PenaltyBreakString: 1000
-# PenaltyExcessCharacter: 1000000
-# PenaltyReturnTypeOnItsOwnLine: 60
 PointerAlignment: Left
-# RawStringFormats:
-#   - Delimiter:       pb
-#     Language:        TextProto
-#     BasedOnStyle:    google
-# ReflowComments:  true
-# SortIncludes:    true
-# SortUsingDeclarations: true
-# SpaceAfterCStyleCast: false
-# SpaceAfterTemplateKeyword: true
-# SpaceBeforeAssignmentOperators: true
-# SpaceBeforeParens: ControlStatements
-# SpaceInEmptyParentheses: false
-# SpacesBeforeTrailingComments: 1
-# SpacesInAngles:  false
-# SpacesInContainerLiterals: true
-# SpacesInCStyleCastParentheses: false
-# SpacesInParentheses: false
-# SpacesInSquareBrackets: false
-TabWidth:        4
-UseTab:          Always
----
-### C++ specific config ###
-Language:        Cpp
-Standard:        Cpp11
----
-### ObjC specific config ###
-Language:        ObjC
-ObjCBlockIndentWidth: 4
-# ObjCSpaceAfterProperty: false
-# ObjCSpaceBeforeProtocolList: true
----
-### Java specific config ###
-Language:        Java
-# BreakAfterJavaFieldAnnotations: false
-...
+TabWidth: 4
+UseTab: Always
diff --git a/core/src/Model/Workflow/Value.hpp b/core/src/Model/Workflow/Value.hpp
index 6cd42f3..8b3e63a 100644
--- a/core/src/Model/Workflow/Value.hpp
+++ b/core/src/Model/Workflow/Value.hpp
@@ -1,5 +1,8 @@
 #pragma once
 
+#include "cplt_fwd.hpp"
+#include "Utils/Color.hpp"
+
 #include <iosfwd>
 #include <memory>
 
@@ -17,11 +20,18 @@ public:
 		KindCount = InvalidKind,
 	};
 
+	struct KindInfo
+	{
+		ImGui::IconType PinIcon;
+		RgbaColor PinColor;
+	};
+
 private:
 	Kind mKind;
 
 public:
-	static const char* FormatKind(Kind kind);
+	static const KindInfo& QueryInfo(Kind kind);
+	static const char* Format(Kind kind);
 	static std::unique_ptr<BaseValue> CreateByKind(Kind kind);
 
 	BaseValue(Kind kind);
diff --git a/core/src/Model/Workflow/Value_RTTI.cpp b/core/src/Model/Workflow/Value_RTTI.cpp
index a0c3213..5e24ed7 100644
--- a/core/src/Model/Workflow/Value_RTTI.cpp
+++ b/core/src/Model/Workflow/Value_RTTI.cpp
@@ -1,9 +1,34 @@
 #include "Value.hpp"
 
 #include "Model/Workflow/Values/BasicValues.hpp"
-#include "Utils/Macros.hpp"
+#include "UI/UI.hpp"
 
-const char* BaseValue::FormatKind(Kind kind)
+constexpr BaseValue::KindInfo kNumericInfo{
+	.PinIcon = ImGui::IconType::Circle,
+	.PinColor = RgbaColor(147, 226, 74),
+};
+
+constexpr BaseValue::KindInfo kTextInfo{
+	.PinIcon = ImGui::IconType::Circle,
+	.PinColor = RgbaColor(124, 21, 153),
+};
+
+constexpr  BaseValue::KindInfo kDateTimeInfo{
+	.PinIcon = ImGui::IconType::Diamond,
+	.PinColor = RgbaColor(147, 226, 74),
+};
+
+const BaseValue::KindInfo& BaseValue::QueryInfo(BaseValue::Kind kind)
+{
+	switch (kind) {
+		case KD_Numeric: return kNumericInfo;
+		case KD_Text: break;
+		case KD_DateTime: break;
+		case InvalidKind: break;
+	}
+}
+
+const char* BaseValue::Format(Kind kind)
 {
 	switch (kind) {
 		case KD_Numeric: return "Numeric";
diff --git a/core/src/Model/Workflow/Workflow.hpp b/core/src/Model/Workflow/Workflow.hpp
index 7bcd349..79c2b2f 100644
--- a/core/src/Model/Workflow/Workflow.hpp
+++ b/core/src/Model/Workflow/Workflow.hpp
@@ -17,20 +17,22 @@
 class WorkflowConnection
 {
 public:
-	static constexpr auto kInvalidId = std::numeric_limits<size_t>::max();
+	static constexpr auto kInvalidId = std::numeric_limits<uint32_t>::max();
 
-	/// Used for `LinkId` when interfacing with imgui node editor. Runtime only (not saved to disk and generated when loading).
-	size_t UniqueId;
-	size_t SourceNode;
-	size_t DestinationNode;
-	int SourcePin;
-	int DestinationPin;
+	uint32_t Id;
+	uint32_t SourceNode;
+	uint32_t SourcePin;
+	uint32_t DestinationNode;
+	uint32_t DestinationPin;
 
 public:
 	WorkflowConnection();
 
 	bool IsValid() const;
 
+	/// Used for `LinkId` when interfacing with imgui node editor. Runtime only (not saved to disk and generated when loading).
+	size_t GetLinkId() const;
+
 	void DrawDebugInfo() const;
 	void ReadFrom(std::istream& stream);
 	void WriteTo(std::ostream& stream);
@@ -39,7 +41,8 @@ public:
 class WorkflowNode
 {
 public:
-	static constexpr auto kInvalidId = std::numeric_limits<size_t>::max();
+	static constexpr auto kInvalidId = std::numeric_limits<uint32_t>::max();
+	static constexpr auto kInvalidPinId = std::numeric_limits<uint32_t>::max();
 
 	enum Type
 	{
@@ -64,16 +67,13 @@ public:
 		KindCount = InvalidKind,
 	};
 
-protected:
 	struct InputPin
 	{
-		/// Equivalent of `PinId` when interfacing with imgui node editor. Runtime only (not saved to disk and generated when loading).
-		size_t UniqueId;
-		size_t Connection = WorkflowConnection::kInvalidId;
+		uint32_t Connection = WorkflowConnection::kInvalidId;
 		BaseValue::Kind MatchingType = BaseValue::InvalidKind;
 		bool ConnectionToConst = false;
 
-		/// A constant connection connects from a user-specified constant value, feeding to a valid \c Destination and \c DestinationPin (i.e. input pins).
+		/// A constant connection connects from a user-specified constant value, feeding to a valid \c DestinationNode and \c DestinationPin (i.e. input pins).
 		bool IsConstantConnection() const;
 		bool IsConnected() const;
 		BaseValue::Kind GetMatchingType() const;
@@ -81,26 +81,22 @@ protected:
 
 	struct OutputPin
 	{
-		/// Equivalent of `PinId` when interfacing with imgui node editor. Runtime only (not saved to disk and generated when loading).
-		size_t UniqueId;
-		size_t Connection = WorkflowConnection::kInvalidId;
+		uint32_t Connection = WorkflowConnection::kInvalidId;
 		BaseValue::Kind MatchingType = BaseValue::InvalidKind;
-		bool AllowsMultipleConnections = false;
 
 		bool IsConnected() const;
 		BaseValue::Kind GetMatchingType() const;
 	};
 
+protected:
 	friend class Workflow;
 	friend class WorkflowEvaluationContext;
 
 	Workflow* mWorkflow;
-	/// Equivalent of `NodeId` when interfacing with imgui node editor. Runtime only (not saved to disk and generated when loading).
-	size_t mUniqueId;
-	size_t mId;
 	std::vector<InputPin> mInputs;
 	std::vector<OutputPin> mOutputs;
 	Vec2i mPosition;
+	uint32_t mId;
 	Kind mKind;
 	int mDepth;
 
@@ -120,7 +116,9 @@ public:
 	void SetPosition(const Vec2i& position);
 	Vec2i GetPosition() const;
 
-	size_t GetId() const;
+	uint32_t GetId() const;
+	/// Used for `NodeId` when interfacing with imgui node editor. Runtime only (not saved to disk and generated when loading).
+	size_t GetNodeId() const;
 	Kind GetKind() const;
 	int GetDepth() const;
 
@@ -128,13 +126,15 @@ public:
 	bool IsInputNode() const;
 	bool IsOutputNode() const;
 
-	void ConnectInput(int nodeId, WorkflowNode& output, int outputNodeId);
-	void DisconnectInput(int nodeId);
-	bool IsInputConnected(int nodeId) const;
+	void ConnectInput(uint32_t pinId, WorkflowNode& output, uint32_t outputNodeId);
+	void DisconnectInput(uint32_t pinId);
+	const InputPin& GetInputPin(uint32_t pinId)const ;
+	size_t GetInputPinUniqueId(uint32_t pinId) const;
 
-	void ConnectOutput(int nodeId, WorkflowNode& input, int inputNodeId);
-	void DisconnectOutput(int nodeId);
-	bool IsOutputConnected(int nodeId) const;
+	void ConnectOutput(uint32_t pinId, WorkflowNode& input, uint32_t inputNodeId);
+	void DisconnectOutput(uint32_t pinId);
+	const OutputPin& GetOutputPin(uint32_t pinId)const ;
+	size_t GetOutputPinUniqueId(uint32_t pinId) const;
 
 	virtual void Evaluate(WorkflowEvaluationContext& ctx) = 0;
 
@@ -157,20 +157,20 @@ protected:
 
 	/* For \c Workflow to invoke, override by implementations */
 
-	void OnAttach(Workflow& workflow, size_t newId) {}
-	void OnDetach() {}
+	void OnAttach(Workflow& workflow, uint32_t newId);
+	void OnDetach();
 };
 
 class Workflow
 {
 private:
+	friend class WorkflowNode;
 	friend class WorkflowEvaluationContext;
 
-	size_t mUniqueId = 0;
 	std::vector<WorkflowConnection> mConnections;
 	std::vector<std::unique_ptr<WorkflowNode>> mNodes;
 	std::vector<std::unique_ptr<BaseValue>> mConstants;
-	std::vector<std::vector<size_t>> mDepthGroups;
+	std::vector<std::vector<uint32_t>> mDepthGroups;
 	int mConnectionCount;
 	int mNodeCount;
 	int mConstantCount;
@@ -186,23 +186,36 @@ public:
 	const std::vector<std::unique_ptr<BaseValue>>& GetConstants() const;
 	std::vector<std::unique_ptr<BaseValue>>& GetConstants();
 
-	WorkflowConnection* GetConnectionById(size_t id);
-	WorkflowNode* GetStepById(size_t id);
-	BaseValue* GetConstantById(size_t id);
+	WorkflowConnection* GetConnectionById(uint32_t id);
+	WorkflowNode* GetNodeById(uint32_t id);
+	BaseValue* GetConstantById(uint32_t id);
+
+	struct GlobalPinId
+	{
+		WorkflowNode* Node;
+		uint32_t PinId;
+		/// true => input pin
+		/// false => output pin
+		bool IsOutput;
+	};
+
+	/// `pinId` should be the `UniqueId` of a pin from a node that's within this workflow.
+	GlobalPinId DisassembleGlobalPinId(size_t id);
+	size_t FabricateGlobalPinId(const WorkflowNode& node, uint32_t pinId, bool isOutput) const;
 
-	const std::vector<std::vector<size_t>>& GetDepthGroups() const;
+	const std::vector<std::vector<uint32_t>>& GetDepthGroups() const;
 	bool DoesDepthNeedsUpdate() const;
 
 	/* Graph mutation */
 
-	void AddStep(std::unique_ptr<WorkflowNode> step);
-	void RemoveStep(size_t id);
+	void AddNode(std::unique_ptr<WorkflowNode> step);
+	void RemoveNode(uint32_t id);
 
-	void RemoveConnection(size_t id);
+	void RemoveConnection(uint32_t id);
 
-	bool Connect(WorkflowNode& sourceNode, int sourcePin, WorkflowNode& destinationNode, int destinationPin);
-	bool DisconnectBySource(WorkflowNode& sourceNode, int sourcePin);
-	bool DisconnectByDestination(WorkflowNode& destinationNode, int destinationPin);
+	bool Connect(WorkflowNode& sourceNode, uint32_t sourcePin, WorkflowNode& destinationNode, uint32_t destinationPin);
+	bool DisconnectBySource(WorkflowNode& sourceNode, uint32_t sourcePin);
+	bool DisconnectByDestination(WorkflowNode& destinationNode, uint32_t destinationPin);
 
 	/* Graph rebuild */
 
@@ -218,12 +231,12 @@ public:
 
 		struct UnsatisfiedDependencies
 		{
-			std::vector<size_t> UnsatisfiedNodes;
+			std::vector<uint32_t> UnsatisfiedNodes;
 		};
 
 		struct UnreachableNodes
 		{
-			std::vector<size_t> UnreachableNodes;
+			std::vector<uint32_t> UnreachableNodes;
 		};
 
 		using T = std::variant<
@@ -246,7 +259,6 @@ public:
 	void WriteTo(std::ostream& stream);
 
 private:
-	size_t AllocUniqueId();
 	std::pair<WorkflowConnection&, size_t> AllocWorkflowConnection();
 	std::pair<std::unique_ptr<WorkflowNode>&, size_t> AllocWorkflowStep();
 };
diff --git a/core/src/Model/Workflow/Workflow_Main.cpp b/core/src/Model/Workflow/Workflow_Main.cpp
index cfa7cea..678b4b8 100644
--- a/core/src/Model/Workflow/Workflow_Main.cpp
+++ b/core/src/Model/Workflow/Workflow_Main.cpp
@@ -3,7 +3,6 @@
 #include <imgui.h>
 #include <imgui_node_editor.h>
 #include <tsl/robin_set.h>
-#include <algorithm>
 #include <cassert>
 #include <iostream>
 #include <queue>
@@ -12,38 +11,46 @@
 namespace ImNodes = ax::NodeEditor;
 
 WorkflowConnection::WorkflowConnection()
-	: SourceNode{ WorkflowNode::kInvalidId }
+	: Id{ 0 }
+	, SourceNode{ WorkflowNode::kInvalidId }
 	, DestinationNode{ WorkflowNode::kInvalidId }
-	, SourcePin{ -1 }
-	, DestinationPin{ -1 }
+	, SourcePin{ WorkflowNode::kInvalidPinId }
+	, DestinationPin{ WorkflowNode::kInvalidPinId }
 {
 }
 
 bool WorkflowConnection::IsValid() const
 {
-	return SourceNode != WorkflowNode::kInvalidId;
+	return Id != 0;
+}
+
+size_t WorkflowConnection::GetLinkId() const
+{
+	// Our id is 0-based (represents an index directly)
+	// but imgui-node-editor uses the value 0 to represent a null id, so we need to offset by 1
+	return Id + 1;
 }
 
 void WorkflowConnection::DrawDebugInfo() const
 {
 	ImGui::BeginTooltip();
 	ImGui::Text("Source (node with output pin):");
-	ImGui::Text("{ Node = %llu, Pin = %d }", SourceNode, SourcePin);
+	ImGui::Text("{ Node = %u, Pin = %u }", SourceNode, SourcePin);
 	ImGui::Text("Destination (node with input pin):");
-	ImGui::Text("{ Node = %llu, Pin = %d }", DestinationNode, DestinationPin);
+	ImGui::Text("{ Node = %u, Pin = %u }", DestinationNode, DestinationPin);
 	ImGui::EndTooltip();
 }
 
 void WorkflowConnection::ReadFrom(std::istream& stream)
 {
-	stream >> SourceNode >> DestinationNode;
-	stream >> SourcePin >> DestinationPin;
+	stream >> SourceNode >> SourcePin;
+	stream >> DestinationNode >> DestinationPin;
 }
 
 void WorkflowConnection::WriteTo(std::ostream& stream)
 {
-	stream << SourceNode << DestinationNode;
-	stream << SourcePin << DestinationPin;
+	stream << SourceNode << SourcePin;
+	stream << DestinationNode << DestinationPin;
 }
 
 bool WorkflowNode::InputPin::IsConstantConnection() const
@@ -87,11 +94,17 @@ void WorkflowNode::SetPosition(const Vec2i& position)
 	mPosition = position;
 }
 
-size_t WorkflowNode::GetId() const
+uint32_t WorkflowNode::GetId() const
 {
 	return mId;
 }
 
+size_t WorkflowNode::GetNodeId() const
+{
+	// See WorkflowConnection::GetLinkId for the rationale
+	return mId + 1;
+}
+
 WorkflowNode::Kind WorkflowNode::GetKind() const
 {
 	return mKind;
@@ -123,47 +136,57 @@ bool WorkflowNode::IsOutputNode() const
 	return mOutputs.size() == 0;
 }
 
-void WorkflowNode::ConnectInput(int nodeId, WorkflowNode& output, int outputNodeId)
+void WorkflowNode::ConnectInput(uint32_t pinId, WorkflowNode& output, uint32_t outputNodeId)
+{
+	mWorkflow->Connect(*this, pinId, output, outputNodeId);
+}
+
+void WorkflowNode::DisconnectInput(uint32_t pinId)
+{
+	mWorkflow->DisconnectByDestination(*this, pinId);
+}
+
+const WorkflowNode::InputPin& WorkflowNode::GetInputPin(uint32_t pinId) const
 {
-	mWorkflow->Connect(*this, nodeId, output, outputNodeId);
+	return mInputs[pinId];
 }
 
-void WorkflowNode::DisconnectInput(int nodeId)
+size_t WorkflowNode::GetInputPinUniqueId(uint32_t pinId) const
 {
-	mWorkflow->DisconnectByDestination(*this, nodeId);
+	return mWorkflow->FabricateGlobalPinId(*this, pinId, false);
 }
 
-bool WorkflowNode::IsInputConnected(int nodeId) const
+void WorkflowNode::ConnectOutput(uint32_t pinId, WorkflowNode& input, uint32_t inputNodeId)
 {
-	return mInputs[nodeId].IsConnected();
+	mWorkflow->Connect(input, inputNodeId, *this, pinId);
 }
 
-void WorkflowNode::ConnectOutput(int nodeId, WorkflowNode& input, int inputNodeId)
+void WorkflowNode::DisconnectOutput(uint32_t pinId)
 {
-	mWorkflow->Connect(input, inputNodeId, *this, nodeId);
+	mWorkflow->DisconnectBySource(*this, pinId);
 }
 
-void WorkflowNode::DisconnectOutput(int nodeId)
+const WorkflowNode::OutputPin& WorkflowNode::GetOutputPin(uint32_t pinId) const
 {
-	mWorkflow->DisconnectBySource(*this, nodeId);
+	return mOutputs[pinId];
 }
 
-bool WorkflowNode::IsOutputConnected(int nodeId) const
+size_t WorkflowNode::GetOutputPinUniqueId(uint32_t pinId) const
 {
-	return mOutputs[nodeId].IsConnected();
+	return mWorkflow->FabricateGlobalPinId(*this, pinId, true);
 }
 
 void WorkflowNode::Draw()
 {
-	for (size_t i = 0; i < mInputs.size(); ++i) {
+	for (uint32_t i = 0; i < mInputs.size(); ++i) {
 		auto& pin = mInputs[i];
-		ImNodes::BeginPin(i, ImNodes::PinKind::Input);
+		ImNodes::BeginPin(GetInputPinUniqueId(i), ImNodes::PinKind::Input);
 		// TODO
 		ImNodes::EndPin();
 	}
-	for (size_t i = 0; i < mOutputs.size(); ++i) {
+	for (uint32_t i = 0; i < mOutputs.size(); ++i) {
 		auto& pin = mOutputs[i];
-		ImNodes::BeginPin(i + mInputs.size(), ImNodes::PinKind::Output);
+		ImNodes::BeginPin(GetOutputPinUniqueId(i), ImNodes::PinKind::Output);
 		// TODO
 		ImNodes::EndPin();
 	}
@@ -174,7 +197,7 @@ void WorkflowNode::DrawDebugInfo() const
 	ImGui::BeginTooltip();
 	ImGui::Text("Node kind: %s", FormatKind(mKind));
 	ImGui::Text("Node type: %s", FormatType(GetType()));
-	ImGui::Text("Node ID: %llu", mId);
+	ImGui::Text("Node ID: %u", mId);
 	ImGui::Text("Depth: %d", mDepth);
 	DrawExtraDebugInfo();
 	ImGui::EndTooltip();
@@ -272,6 +295,14 @@ void WorkflowNode::SwapOutputPin(int a, int b)
 	std::swap(pinA, pinB);
 }
 
+void WorkflowNode::OnAttach(Workflow& workflow, uint32_t newId)
+{
+}
+
+void WorkflowNode::OnDetach()
+{
+}
+
 const std::vector<WorkflowConnection>& Workflow::GetConnections() const
 {
 	return mConnections;
@@ -302,22 +333,57 @@ std::vector<std::unique_ptr<BaseValue>>& Workflow::GetConstants()
 	return mConstants;
 }
 
-WorkflowConnection* Workflow::GetConnectionById(size_t id)
+WorkflowConnection* Workflow::GetConnectionById(uint32_t id)
 {
 	return &mConnections[id];
 }
 
-WorkflowNode* Workflow::GetStepById(size_t id)
+WorkflowNode* Workflow::GetNodeById(uint32_t id)
 {
 	return mNodes[id].get();
 }
 
-BaseValue* Workflow::GetConstantById(size_t id)
+BaseValue* Workflow::GetConstantById(uint32_t id)
 {
 	return mConstants[id].get();
 }
 
-const std::vector<std::vector<size_t>>& Workflow::GetDepthGroups() const
+Workflow::GlobalPinId Workflow::DisassembleGlobalPinId(size_t id)
+{
+	// imgui-node-editor requires all pins to have a global, unique id
+	// but in our model the pin are typed (input vs output) and associated with a node: there is no built-in global id
+	// Therefore we encode one ourselves
+
+	// Global pin id format
+	// nnnnnnnn nnnnnnnn nnnnnnnn nnnnnnnn Tppppppp pppppppp pppppppp pppppppp
+	// <------- (32 bits) node id -------> ^<------ (31 bits) pin id -------->
+	//                                     | (1 bit) input (false) vs output (true)
+
+	// 1 is added to pin id to prevent the 0th node's 0th input pin resulting in a 0 global pin id
+	// (this is problematic because imgui-node-editor use 0 to represent null)
+
+	GlobalPinId result;
+
+	result.Node = mNodes[id >> 32].get();
+	result.PinId = (uint32_t)(id & 0x000000001FFFFFFF) - 1;
+	result.IsOutput = id >> 31;
+
+	return result;
+}
+
+size_t Workflow::FabricateGlobalPinId(const WorkflowNode& node, uint32_t pinId, bool isOutput) const
+{
+	// See this->DisassembleGlobalPinId for format details and rationale
+
+	uint64_t id = 0;
+	id |= ((uint64_t)node.GetId() << 32);
+	id |= (isOutput << 31);
+	id |= ((pinId + 1) & 0x1FFFFFFF);
+
+	return id;
+}
+
+const std::vector<std::vector<uint32_t>>& Workflow::GetDepthGroups() const
 {
 	return mDepthGroups;
 }
@@ -327,7 +393,7 @@ bool Workflow::DoesDepthNeedsUpdate() const
 	return mDepthsDirty;
 }
 
-void Workflow::AddStep(std::unique_ptr<WorkflowNode> step)
+void Workflow::AddNode(std::unique_ptr<WorkflowNode> step)
 {
 	auto [storage, id] = AllocWorkflowStep();
 	storage = std::move(step);
@@ -336,7 +402,7 @@ void Workflow::AddStep(std::unique_ptr<WorkflowNode> step)
 	storage->mId = id;
 }
 
-void Workflow::RemoveStep(size_t id)
+void Workflow::RemoveNode(uint32_t id)
 {
 	auto& step = mNodes[id];
 	if (step == nullptr) return;
@@ -346,7 +412,7 @@ void Workflow::RemoveStep(size_t id)
 	step->mId = WorkflowNode::kInvalidId;
 }
 
-void Workflow::RemoveConnection(size_t id)
+void Workflow::RemoveConnection(uint32_t id)
 {
 	auto& conn = mConnections[id];
 	if (!conn.IsValid()) return;
@@ -358,7 +424,7 @@ void Workflow::RemoveConnection(size_t id)
 	mDepthsDirty = true;
 }
 
-bool Workflow::Connect(WorkflowNode& sourceNode, int sourcePin, WorkflowNode& destinationNode, int destinationPin)
+bool Workflow::Connect(WorkflowNode& sourceNode, uint32_t sourcePin, WorkflowNode& destinationNode, uint32_t destinationPin)
 {
 	auto& src = sourceNode.mOutputs[sourcePin];
 	auto& dst = destinationNode.mInputs[destinationPin];
@@ -385,7 +451,7 @@ bool Workflow::Connect(WorkflowNode& sourceNode, int sourcePin, WorkflowNode& de
 	return true;
 }
 
-bool Workflow::DisconnectBySource(WorkflowNode& sourceNode, int sourcePin)
+bool Workflow::DisconnectBySource(WorkflowNode& sourceNode, uint32_t sourcePin)
 {
 	auto& sn = sourceNode.mOutputs[sourcePin];
 	if (!sn.IsConnected()) return false;
@@ -401,7 +467,7 @@ bool Workflow::DisconnectBySource(WorkflowNode& sourceNode, int sourcePin)
 	return true;
 }
 
-bool Workflow::DisconnectByDestination(WorkflowNode& destinationNode, int destinationPin)
+bool Workflow::DisconnectByDestination(WorkflowNode& destinationNode, uint32_t destinationPin)
 {
 	auto& dn = destinationNode.mOutputs[destinationPin];
 	if (!dn.IsConnected()) return false;
@@ -436,7 +502,7 @@ Workflow::GraphUpdateResult::T Workflow::UpdateGraph()
 	};
 
 	std::vector<WorkingNode> workingNodes;
-	std::queue<size_t> q;
+	std::queue<uint32_t> q;
 
 	// Check if all dependencies of this node is satisfied
 	auto CheckNodeDependencies = [&](WorkflowNode& node) -> bool {
@@ -450,8 +516,8 @@ Workflow::GraphUpdateResult::T Workflow::UpdateGraph()
 
 	workingNodes.reserve(mNodes.size());
 	{
-		std::vector<size_t> unsatisfiedNodes;
-		for (size_t i = 0; i < mNodes.size(); ++i) {
+		std::vector<uint32_t> unsatisfiedNodes;
+		for (uint32_t i = 0; i < mNodes.size(); ++i) {
 			auto& node = mNodes[i];
 			workingNodes.push_back(WorkingNode{});
 
@@ -506,8 +572,8 @@ Workflow::GraphUpdateResult::T Workflow::UpdateGraph()
 	if (processedNodes < mNodes.size()) {
 		// There is unreachable nodes, collect them and report to the caller
 
-		std::vector<size_t> unreachableNodes;
-		for (size_t i = 0; i < mNodes.size(); ++i) {
+		std::vector<uint32_t> unreachableNodes;
+		for (uint32_t i = 0; i < mNodes.size(); ++i) {
 			auto& wn = workingNodes[i];
 			auto& n = *mNodes[i];
 
@@ -526,41 +592,32 @@ Workflow::GraphUpdateResult::T Workflow::UpdateGraph()
 Workflow::ReadResult Workflow::ReadFrom(std::istream& stream)
 {
 	auto DeserializeV0 = [&]() {
-		size_t connectionsStorage, nodesStorage, constantsStorage;
-		stream >> connectionsStorage >> nodesStorage >> constantsStorage;
-
 		uint32_t connectionCount, nodeCount, constantCount;
 		stream >> connectionCount >> nodeCount >> constantCount;
 
+		mConnections.reserve(connectionCount);
 		for (uint32_t i = 0; i < connectionCount; ++i) {
-			size_t idx;
-			stream >> idx;
-
-			mConnections[idx].ReadFrom(stream);
+			mConnections.emplace_back().ReadFrom(stream);
 		}
 
+		mNodes.reserve(connectionCount);
 		for (uint32_t i = 0; i < nodeCount; ++i) {
-			size_t idx;
-			stream >> idx;
-
 			uint32_t nKind;
 			stream >> nKind;
 			auto kind = (WorkflowNode::Kind)nKind;
 
-			mNodes[idx] = WorkflowNode::CreateByKind(kind);
-			mNodes[idx]->ReadFrom(stream);
+			mNodes.push_back(WorkflowNode::CreateByKind(kind));
+			mNodes.back()->ReadFrom(stream);
 		}
 
+		mConstants.reserve(connectionCount);
 		for (uint32_t i = 0; i < constantCount; ++i) {
-			size_t idx;
-			stream >> idx;
-
 			uint32_t nKind;
 			stream >> nKind;
 			auto kind = (BaseValue::Kind)nKind;
 
-			mConstants[idx] = BaseValue::CreateByKind(kind);
-			mConstants[idx]->ReadFrom(stream);
+			mConstants.push_back(BaseValue::CreateByKind(kind));
+			mConstants.back()->ReadFrom(stream);
 		}
 	};
 
@@ -579,6 +636,8 @@ void Workflow::WriteTo(std::ostream& stream)
 	// Version
 	stream << (uint64_t)0;
 
+	// TODO id compacting
+
 	stream << (size_t)mConnections.size();
 	stream << (size_t)mNodes.size();
 	stream << (size_t)mConstants.size();
@@ -621,7 +680,10 @@ std::pair<WorkflowConnection&, size_t> Workflow::AllocWorkflowConnection()
 	}
 
 	auto id = mConnections.size();
-	return { mConnections.emplace_back(WorkflowConnection{}), id };
+	auto& conn = mConnections.emplace_back(WorkflowConnection{});
+	conn.Id = id;
+
+	return { conn, id };
 }
 
 std::pair<std::unique_ptr<WorkflowNode>&, size_t> Workflow::AllocWorkflowStep()
@@ -634,10 +696,7 @@ std::pair<std::unique_ptr<WorkflowNode>&, size_t> Workflow::AllocWorkflowStep()
 	}
 
 	auto id = mNodes.size();
-	return { mNodes.emplace_back(std::unique_ptr<WorkflowNode>()), id };
-}
+	auto& node = mNodes.emplace_back(std::unique_ptr<WorkflowNode>());
 
-size_t Workflow::AllocUniqueId()
-{
-	return mUniqueId++;
+	return { node, id };
 }
diff --git a/core/src/UI/UI.hpp b/core/src/UI/UI.hpp
index 9e97118..cce0e00 100644
--- a/core/src/UI/UI.hpp
+++ b/core/src/UI/UI.hpp
@@ -18,6 +18,19 @@ void ErrorMessage(const char* fmt, ...);
 void WarningIcon();
 void WarningMessage(const char* fmt, ...);
 
+enum class IconType
+{
+	Flow,
+	Circle,
+	Square,
+	Grid,
+	RoundSquare,
+	Diamond,
+};
+
+void DrawIcon(ImDrawList* drawList, const ImVec2& a, const ImVec2& b, IconType type, bool filled, ImU32 color, ImU32 innerColor);
+void Icon(const ImVec2& size, IconType type, bool filled, const ImVec4& color = ImVec4(1, 1, 1, 1), const ImVec4& innerColor = ImVec4(0, 0, 0, 0));
+
 } // namespace ImGui
 
 namespace UI {
diff --git a/core/src/UI/UI_Utils.cpp b/core/src/UI/UI_Utils.cpp
index 15f88cf..d662d2c 100644
--- a/core/src/UI/UI_Utils.cpp
+++ b/core/src/UI/UI_Utils.cpp
@@ -2,6 +2,8 @@
 
 #include <IconsFontAwesome.h>
 #include <imgui.h>
+
+#define IMGUI_DEFINE_MATH_OPERATORS
 #include <imgui_internal.h>
 
 void ImGui::SetNextWindowSizeRelScreen(float xPercent, float yPercent, ImGuiCond cond)
@@ -77,3 +79,220 @@ void ImGui::WarningMessage(const char* fmt, ...)
 	TextV(fmt, args);
 	va_end(args);
 }
+
+void ImGui::DrawIcon(ImDrawList* drawList, const ImVec2& a, const ImVec2& b, IconType type, bool filled, ImU32 color, ImU32 innerColor)
+{
+	// Taken from https://github.com/thedmd/imgui-node-editor/blob/master/examples/blueprints-example/utilities/drawing.cpp
+	// ax::NodeEditor::DrawIcon
+
+	// Brace style was adapted but no names are changed
+
+	auto rect = ImRect(a, b);
+	auto rect_x = rect.Min.x;
+	auto rect_y = rect.Min.y;
+	auto rect_w = rect.Max.x - rect.Min.x;
+	auto rect_h = rect.Max.y - rect.Min.y;
+	auto rect_center_x = (rect.Min.x + rect.Max.x) * 0.5f;
+	auto rect_center_y = (rect.Min.y + rect.Max.y) * 0.5f;
+	auto rect_center = ImVec2(rect_center_x, rect_center_y);
+	const auto outline_scale = rect_w / 24.0f;
+	const auto extra_segments = static_cast<int>(2 * outline_scale); // for full circle
+
+	if (type == IconType::Flow) {
+		const auto origin_scale = rect_w / 24.0f;
+
+		const auto offset_x = 1.0f * origin_scale;
+		const auto offset_y = 0.0f * origin_scale;
+		const auto margin = 2.0f * origin_scale;
+		const auto rounding = 0.1f * origin_scale;
+		const auto tip_round = 0.7f; // percentage of triangle edge (for tip)
+		//const auto edge_round = 0.7f; // percentage of triangle edge (for corner)
+		const auto canvas = ImRect(
+			rect.Min.x + margin + offset_x,
+			rect.Min.y + margin + offset_y,
+			rect.Max.x - margin + offset_x,
+			rect.Max.y - margin + offset_y);
+		const auto canvas_x = canvas.Min.x;
+		const auto canvas_y = canvas.Min.y;
+		const auto canvas_w = canvas.Max.x - canvas.Min.x;
+		const auto canvas_h = canvas.Max.y - canvas.Min.y;
+
+		const auto left = canvas_x + canvas_w * 0.5f * 0.3f;
+		const auto right = canvas_x + canvas_w - canvas_w * 0.5f * 0.3f;
+		const auto top = canvas_y + canvas_h * 0.5f * 0.2f;
+		const auto bottom = canvas_y + canvas_h - canvas_h * 0.5f * 0.2f;
+		const auto center_y = (top + bottom) * 0.5f;
+		//const auto angle = AX_PI * 0.5f * 0.5f * 0.5f;
+
+		const auto tip_top = ImVec2(canvas_x + canvas_w * 0.5f, top);
+		const auto tip_right = ImVec2(right, center_y);
+		const auto tip_bottom = ImVec2(canvas_x + canvas_w * 0.5f, bottom);
+
+		drawList->PathLineTo(ImVec2(left, top) + ImVec2(0, rounding));
+		drawList->PathBezierCurveTo(
+			ImVec2(left, top),
+			ImVec2(left, top),
+			ImVec2(left, top) + ImVec2(rounding, 0));
+		drawList->PathLineTo(tip_top);
+		drawList->PathLineTo(tip_top + (tip_right - tip_top) * tip_round);
+		drawList->PathBezierCurveTo(
+			tip_right,
+			tip_right,
+			tip_bottom + (tip_right - tip_bottom) * tip_round);
+		drawList->PathLineTo(tip_bottom);
+		drawList->PathLineTo(ImVec2(left, bottom) + ImVec2(rounding, 0));
+		drawList->PathBezierCurveTo(
+			ImVec2(left, bottom),
+			ImVec2(left, bottom),
+			ImVec2(left, bottom) - ImVec2(0, rounding));
+
+		if (!filled) {
+			if (innerColor & 0xFF000000) {
+				drawList->AddConvexPolyFilled(drawList->_Path.Data, drawList->_Path.Size, innerColor);
+			}
+
+			drawList->PathStroke(color, true, 2.0f * outline_scale);
+		} else {
+			drawList->PathFillConvex(color);
+		}
+	} else {
+		auto triangleStart = rect_center_x + 0.32f * rect_w;
+
+		auto rect_offset = -static_cast<int>(rect_w * 0.25f * 0.25f);
+
+		rect.Min.x += rect_offset;
+		rect.Max.x += rect_offset;
+		rect_x += rect_offset;
+		rect_center_x += rect_offset * 0.5f;
+		rect_center.x += rect_offset * 0.5f;
+
+		if (type == IconType::Circle) {
+			const auto c = rect_center;
+
+			if (!filled) {
+				const auto r = 0.5f * rect_w / 2.0f - 0.5f;
+
+				if (innerColor & 0xFF000000)
+					drawList->AddCircleFilled(c, r, innerColor, 12 + extra_segments);
+				drawList->AddCircle(c, r, color, 12 + extra_segments, 2.0f * outline_scale);
+			} else {
+				drawList->AddCircleFilled(c, 0.5f * rect_w / 2.0f, color, 12 + extra_segments);
+			}
+		}
+
+		if (type == IconType::Square) {
+			if (filled) {
+				const auto r = 0.5f * rect_w / 2.0f;
+				const auto p0 = rect_center - ImVec2(r, r);
+				const auto p1 = rect_center + ImVec2(r, r);
+
+				drawList->AddRectFilled(p0, p1, color, 0, 15 + extra_segments);
+			} else {
+				const auto r = 0.5f * rect_w / 2.0f - 0.5f;
+				const auto p0 = rect_center - ImVec2(r, r);
+				const auto p1 = rect_center + ImVec2(r, r);
+
+				if (innerColor & 0xFF000000)
+					drawList->AddRectFilled(p0, p1, innerColor, 0, 15 + extra_segments);
+
+				drawList->AddRect(p0, p1, color, 0, 15 + extra_segments, 2.0f * outline_scale);
+			}
+		}
+
+		if (type == IconType::Grid) {
+			const auto r = 0.5f * rect_w / 2.0f;
+			const auto w = ceilf(r / 3.0f);
+
+			const auto baseTl = ImVec2(floorf(rect_center_x - w * 2.5f), floorf(rect_center_y - w * 2.5f));
+			const auto baseBr = ImVec2(floorf(baseTl.x + w), floorf(baseTl.y + w));
+
+			auto tl = baseTl;
+			auto br = baseBr;
+			for (int i = 0; i < 3; ++i) {
+				tl.x = baseTl.x;
+				br.x = baseBr.x;
+				drawList->AddRectFilled(tl, br, color);
+				tl.x += w * 2;
+				br.x += w * 2;
+				if (i != 1 || filled)
+					drawList->AddRectFilled(tl, br, color);
+				tl.x += w * 2;
+				br.x += w * 2;
+				drawList->AddRectFilled(tl, br, color);
+
+				tl.y += w * 2;
+				br.y += w * 2;
+			}
+
+			triangleStart = br.x + w + 1.0f / 24.0f * rect_w;
+		}
+
+		if (type == IconType::RoundSquare) {
+			if (filled) {
+				const auto r = 0.5f * rect_w / 2.0f;
+				const auto cr = r * 0.5f;
+				const auto p0 = rect_center - ImVec2(r, r);
+				const auto p1 = rect_center + ImVec2(r, r);
+
+				drawList->AddRectFilled(p0, p1, color, cr, 15);
+			} else {
+				const auto r = 0.5f * rect_w / 2.0f - 0.5f;
+				const auto cr = r * 0.5f;
+				const auto p0 = rect_center - ImVec2(r, r);
+				const auto p1 = rect_center + ImVec2(r, r);
+
+				if (innerColor & 0xFF000000)
+					drawList->AddRectFilled(p0, p1, innerColor, cr, 15);
+
+				drawList->AddRect(p0, p1, color, cr, 15, 2.0f * outline_scale);
+			}
+		} else if (type == IconType::Diamond) {
+			if (filled) {
+				const auto r = 0.607f * rect_w / 2.0f;
+				const auto c = rect_center;
+
+				drawList->PathLineTo(c + ImVec2(0, -r));
+				drawList->PathLineTo(c + ImVec2(r, 0));
+				drawList->PathLineTo(c + ImVec2(0, r));
+				drawList->PathLineTo(c + ImVec2(-r, 0));
+				drawList->PathFillConvex(color);
+			} else {
+				const auto r = 0.607f * rect_w / 2.0f - 0.5f;
+				const auto c = rect_center;
+
+				drawList->PathLineTo(c + ImVec2(0, -r));
+				drawList->PathLineTo(c + ImVec2(r, 0));
+				drawList->PathLineTo(c + ImVec2(0, r));
+				drawList->PathLineTo(c + ImVec2(-r, 0));
+
+				if (innerColor & 0xFF000000)
+					drawList->AddConvexPolyFilled(drawList->_Path.Data, drawList->_Path.Size, innerColor);
+
+				drawList->PathStroke(color, true, 2.0f * outline_scale);
+			}
+		} else {
+			const auto triangleTip = triangleStart + rect_w * (0.45f - 0.32f);
+
+			drawList->AddTriangleFilled(
+				ImVec2(ceilf(triangleTip), rect_y + rect_h * 0.5f),
+				ImVec2(triangleStart, rect_center_y + 0.15f * rect_h),
+				ImVec2(triangleStart, rect_center_y - 0.15f * rect_h),
+				color);
+		}
+	}
+}
+
+void ImGui::Icon(const ImVec2& size, IconType type, bool filled, const ImVec4& color, const ImVec4& innerColor)
+{
+	// Taken from https://github.com/thedmd/imgui-node-editor/blob/master/examples/blueprints-example/utilities/widgets.cpp
+	// ax::NodeEditor::Icon
+
+	if (ImGui::IsRectVisible(size))
+	{
+		auto cursorPos = ImGui::GetCursorScreenPos();
+		auto drawList = ImGui::GetWindowDrawList();
+		DrawIcon(drawList, cursorPos, cursorPos + size, type, filled, ImColor(color), ImColor(innerColor));
+	}
+
+	ImGui::Dummy(size);
+}
diff --git a/core/src/UI/UI_Workflows.cpp b/core/src/UI/UI_Workflows.cpp
index f9857a1..7aefeab 100644
--- a/core/src/UI/UI_Workflows.cpp
+++ b/core/src/UI/UI_Workflows.cpp
@@ -17,9 +17,9 @@
 namespace ImNodes = ax::NodeEditor;
 
 namespace {
-class WorkflowCreationMenu
+class WorkflowDatabase
 {
-private:
+public:
 	using WorkflowNodeConstructor = std::unique_ptr<WorkflowNode> (*)();
 
 	enum Category
@@ -39,6 +39,7 @@ private:
 		Category Category;
 	};
 
+private:
 	std::vector<Candidate> mCandidates;
 
 #define SUB_RANGE_ACCESS(Type, AccessorName, storage, begin, nextBegin) \
@@ -53,6 +54,7 @@ private:
 	int mSystemInputNodes;
 	int mOutputOffset;
 
+public:
 	SUB_RANGE_ACCESS(Candidate, GetNumericNodes, mCandidates, 0, mTextOffset);
 	SUB_RANGE_ACCESS(Candidate, GetTextNodes, mCandidates, mTextOffset, mDocumentOffset);
 	SUB_RANGE_ACCESS(Candidate, GetDocumentNodes, mCandidates, mDocumentOffset, mUserInputOffset);
@@ -63,12 +65,6 @@ private:
 #undef SUB_RANGE_ACCESS
 
 public:
-	WorkflowCreationMenu()
-	{
-		SetupCandidates();
-	}
-
-private:
 	void SetupCandidates()
 	{
 		// Numeric nodes offset start at 0
@@ -140,11 +136,13 @@ class WorkflowUI
 private:
 	Workflow* mWorkflow;
 	ImNodes::EditorContext* mContext;
+	WorkflowDatabase mWorkflowDatabase;
 
 public:
 	WorkflowUI()
 	{
 		mContext = ImNodes::CreateEditor();
+		mWorkflowDatabase.SetupCandidates();
 	}
 
 	~WorkflowUI()
@@ -157,6 +155,8 @@ public:
 		ImNodes::SetCurrentEditor(mContext);
 		ImNodes::Begin("");
 
+		const char* tooltipMessage = nullptr;
+
 		for (auto& node : mWorkflow->GetNodes()) {
 			if (!node) continue;
 
@@ -168,8 +168,112 @@ public:
 		for (auto& conn : mWorkflow->GetConnections()) {
 			if (!conn.IsValid()) continue;
 
-			// TODO create link
+			auto srcId = mWorkflow->GetNodes()[conn.SourceNode]->GetOutputPinUniqueId(conn.SourcePin);
+			auto dstId = mWorkflow->GetNodes()[conn.DestinationNode]->GetInputPinUniqueId(conn.DestinationPin);
+			ImNodes::Link(conn.GetLinkId(), srcId, dstId);
+		}
+
+		if (ImNodes::BeginCreate()) {
+			ImNodes::PinId src = 0, dst = 0;
+			if (ImNodes::QueryNewLink(&src, &dst)) {
+				if (!src || !dst) {
+					goto createError;
+				}
+
+				auto [srcNode, srcPinId, srcIsOutput] = mWorkflow->DisassembleGlobalPinId((size_t)src);
+				auto [dstNode, dstPinId, dstIsOutput] = mWorkflow->DisassembleGlobalPinId((size_t)dst);
+
+				if (srcNode == dstNode) {
+					ImNodes::RejectNewItem();
+					goto createError;
+				}
+
+				if (srcIsOutput == dstIsOutput) {
+					ImNodes::RejectNewItem();
+					goto createError;
+				}
+
+				auto srcPin = srcNode->GetOutputPin(srcPinId);
+				auto dstPin = dstNode->GetOutputPin(dstPinId);
+
+				if (srcPin.MatchingType != dstPin.MatchingType) {
+					ImNodes::RejectNewItem();
+					goto createError;
+				}
+
+				if (ImNodes::AcceptNewItem()) {
+					mWorkflow->Connect(*srcNode, srcPinId, *dstNode, dstPinId);
+				}
+			}
+
+			ImNodes::PinId newNodePin = 0;
+			if (ImNodes::QueryNewNode(&newNodePin)) {
+				auto [node, pinId, isOutput] = mWorkflow->DisassembleGlobalPinId((size_t)newNodePin);
+
+				if ((isOutput && node->GetOutputPin(pinId).IsConnected()) ||
+					(!isOutput && node->GetInputPin(pinId).IsConnected()))
+				{
+					ImNodes::RejectNewItem();
+					goto createError;
+				}
+
+				if (ImNodes::AcceptNewItem()) {
+					ImNodes::Suspend();
+					ImGui::BeginPopup("Create Node");
+					ImNodes::Resume();
+				}
+			}
+		}
+	createError:
+		ImNodes::EndCreate();
+
+		if (ImNodes::BeginDelete()) {
+			ImNodes::LinkId deletedLinkId;
+			if (ImNodes::QueryDeletedLink(&deletedLinkId)) {
+				// Link id is the same as our connection id
+				auto& conn = *mWorkflow->GetConnectionById((size_t)deletedLinkId);
+
+				// TODO
+			}
+		}
+	deleteError:
+		ImNodes::EndDelete();
+
+		// Popups
+		ImNodes::Suspend();
+		if (ImGui::BeginPopup("Node Context Menu")) {
+			// TODO
+			ImGui::EndPopup();
+		}
+		if (ImGui::BeginPopup("Link Context Menu")) {
+			// TODO
+			ImGui::EndPopup();
+		}
+		if (ImGui::BeginPopup("Create Node")) {
+			auto DisplayCandidatesCategory = [&](const char* name, std::span<const WorkflowDatabase::Candidate> candidates) {
+				ImGui::TreeNode(name);
+				for (auto& candidate : candidates) {
+					if (ImGui::MenuItem(candidate.Name.c_str())) {
+						// TODO
+					}
+				}
+				ImGui::TreePop();
+			};
+
+			DisplayCandidatesCategory("Numeric nodes", mWorkflowDatabase.GetNumericNodes());
+			DisplayCandidatesCategory("Text nodes", mWorkflowDatabase.GetTextNodes());
+			DisplayCandidatesCategory("Document nodes", mWorkflowDatabase.GetDocumentNodes());
+			DisplayCandidatesCategory("User input nodes", mWorkflowDatabase.GetUserInputNodes());
+			DisplayCandidatesCategory("System input nodes", mWorkflowDatabase.GetSystemInputNodes());
+			DisplayCandidatesCategory("Output nodes", mWorkflowDatabase.GetOutputNodes());
+			ImGui::EndPopup();
+		}
+		if (tooltipMessage) {
+			ImGui::BeginTooltip();
+			ImGui::TextUnformatted(tooltipMessage);
+			ImGui::EndTooltip();
 		}
+		ImNodes::Resume();
 
 		ImNodes::End();
 	}
diff --git a/core/src/UI/fwd.hpp b/core/src/UI/fwd.hpp
index e412524..45facbe 100644
--- a/core/src/UI/fwd.hpp
+++ b/core/src/UI/fwd.hpp
@@ -5,3 +5,8 @@ class LocaleStrings;
 
 // States.hpp
 class UIState;
+
+// UI.hpp
+namespace ImGui {
+enum class IconType;
+}
diff --git a/core/src/Utils/Color.hpp b/core/src/Utils/Color.hpp
new file mode 100644
index 0000000..26cfdd4
--- /dev/null
+++ b/core/src/Utils/Color.hpp
@@ -0,0 +1,191 @@
+#pragma once

+

+#include "Utils/Vector.hpp"

+#include "Utils/fwd.hpp"

+

+#include <imgui.h>

+#include <algorithm>

+#include <cstdint>

+#include <limits>

+

+class RgbaColor

+{

+public:

+	uint8_t r;

+	uint8_t g;

+	uint8_t b;

+	uint8_t a;

+

+public:

+	constexpr RgbaColor() noexcept

+		: r{ 255 }

+		, g{ 255 }

+		, b{ 255 }

+		, a{ 255 }

+	{

+	}

+

+	constexpr RgbaColor(float r, float g, float b, float a = 1.0f) noexcept

+		: r{ static_cast<uint8_t>(r * 255.0f) }

+		, g{ static_cast<uint8_t>(g * 255.0f) }

+		, b{ static_cast<uint8_t>(b * 255.0f) }

+		, a{ static_cast<uint8_t>(a * 255.0f) }

+	{

+	}

+

+	constexpr RgbaColor(int r, int g, int b, int a = 255) noexcept

+		: r{ static_cast<uint8_t>(r & 0xFF) }

+		, g{ static_cast<uint8_t>(g & 0xFF) }

+		, b{ static_cast<uint8_t>(b & 0xFF) }

+		, a{ static_cast<uint8_t>(a & 0xFF) }

+	{

+	}

+

+	constexpr RgbaColor(uint32_t rgba) noexcept

+		: r{ static_cast<uint8_t>((rgba >> 0) & 0xFF) }

+		, g{ static_cast<uint8_t>((rgba >> 8) & 0xFF) }

+		, b{ static_cast<uint8_t>((rgba >> 16) & 0xFF) }

+		, a{ static_cast<uint8_t>((rgba >> 24) & 0xFF) }

+	{

+	}

+

+	constexpr uint32_t GetScalar() const noexcept

+	{

+		uint32_t res = 0;

+		res |= r << 24;

+		res |= g << 16;

+		res |= b << 8;

+		res |= a;

+		return res;

+	}

+

+	constexpr void SetScalar(uint32_t scalar) noexcept

+	{

+		r = (scalar >> 0) & 0xFF;

+		g = (scalar >> 8) & 0xFF;

+		b = (scalar >> 16) & 0xFF;

+		a = (scalar >> 24) & 0xFF;

+	}

+

+	constexpr float GetNormalizedRed() const noexcept

+	{

+		return r / 255.0f;

+	}

+

+	constexpr float GetNormalizedGreen() const noexcept

+	{

+		return g / 255.0f;

+	}

+

+	constexpr float GetNormalizedBlue() const noexcept

+	{

+		return b / 255.0f;

+	}

+

+	constexpr float GetNormalizedAlpha() const noexcept

+	{

+		return a / 255.0f;

+	}

+

+	constexpr Vec4i AsVec4i() const noexcept

+	{

+		return Vec4i{ r, g, b, a };

+	}

+

+	constexpr Vec4f AsVec4f() const noexcept

+	{

+		return Vec4f{

+			GetNormalizedRed(),

+			GetNormalizedGreen(),

+			GetNormalizedBlue(),

+			GetNormalizedAlpha(),

+		};

+	}

+

+	ImVec4 AsImVec() const

+	{

+		auto v = AsVec4f();

+		return ImVec4{ v.x, v.y, v.z, v.w };

+	}

+

+	ImColor AsImColor() const

+	{

+		auto v = AsVec4f();

+		return ImColor{ v.x, v.y, v.z, v.w };

+	}

+

+	constexpr void SetVec(const Vec4f& vec) noexcept

+	{

+		r = (uint8_t)(vec.x * 255.0f);

+		g = (uint8_t)(vec.y * 255.0f);

+		b = (uint8_t)(vec.z * 255.0f);

+		a = (uint8_t)(vec.w * 255.0f);

+	}

+

+	// Forward declaring because cyclic reference between RgbaColor and HsvColor

+	constexpr HsvColor ToHsv() const noexcept;

+

+	friend constexpr bool operator==(const RgbaColor&, const RgbaColor&) noexcept = default;

+};

+

+class HsvColor

+{

+public:

+	float h;

+	float s;

+	float v;

+	float a;

+

+public:

+	constexpr HsvColor() noexcept

+		: h{ 0.0f }

+		, s{ 0.0f }

+		, v{ 1.0f }

+		, a{ 1.0f }

+	{

+	}

+

+	constexpr HsvColor(float h, float s, float v, float a) noexcept

+		: h{ h }

+		, s{ s }

+		, v{ v }

+		, a{ a }

+	{

+	}

+

+	// Forward declaring because cyclic reference between RgbaColor and HsvColor

+	constexpr RgbaColor ToRgba() const noexcept;

+};

+

+constexpr HsvColor RgbaColor::ToHsv() const noexcept

+{

+	float fr = GetNormalizedRed();

+	float fg = GetNormalizedBlue();

+	float fb = GetNormalizedGreen();

+	float fa = GetNormalizedAlpha();

+

+	auto p = fg < fb ? ImVec4(fb, fg, -1, 2.0f / 3.0f) : ImVec4(fg, fb, 0, -1.0f / 3.0f);

+	auto q = fr < p.x ? ImVec4(p.x, p.y, p.w, fr) : ImVec4(fr, p.y, p.z, p.x);

+	float c = q.x - std::min(q.w, q.y);

+	float h = std::abs((q.w - q.y) / (6 * c + std::numeric_limits<float>::epsilon()) + q.z);

+

+	Vec3f hcv{ h, c, q.x };

+	float s = hcv.y / (hcv.z + std::numeric_limits<float>::epsilon());

+	return HsvColor(hcv.x, s, hcv.z, fa);

+}

+

+constexpr RgbaColor HsvColor::ToRgba() const noexcept

+{

+	float r = std::abs(h * 6 - 3) - 1;

+	float g = 2 - std::abs(h * 6 - 2);

+	float b = 2 - std::abs(h * 6 - 4);

+

+	auto rgb = Vec3f{

+		std::clamp(r, 0.0f, 1.0f),

+		std::clamp(g, 0.0f, 1.0f),

+		std::clamp(b, 0.0f, 1.0f),

+	};

+	auto vc = (rgb - Vec3f{ 0, 0, 0 }) * s + Vec3f{ 1, 1, 1 } * v;

+

+	return RgbaColor(vc.x, vc.y, vc.z, a);

+}

diff --git a/core/src/Utils/Enum.hpp b/core/src/Utils/Enum.hpp
deleted file mode 100644
index 1fb9661..0000000
--- a/core/src/Utils/Enum.hpp
+++ /dev/null
@@ -1,140 +0,0 @@
-#pragma once
-
-#include <compare>
-
-template <class TSelf>
-struct BasicEnum
-{
-	using Self = TSelf;
-	using ValueType = int;
-
-	int value;
-
-	BasicEnum()
-		: value{ 0 } {}
-	BasicEnum(int value)
-		: value{ value } {}
-
-	/// Comparison between 2 values of enum. Useful for situations like `a == b` where both a and b are TSelf.
-	friend auto operator<=>(const TSelf& a, const TSelf& b)
-	{
-		return a.value <=> b.value;
-	}
-
-	/// Comparison between a enum and a raw value. Useful for situations like `a == TSelf::Option` where a is a enum and TSelf::Option is a raw value.
-	friend auto operator<=>(const TSelf& self, int value)
-	{
-		return self.value <=> value;
-	}
-
-	operator int() const
-	{
-		return value;
-	}
-
-	operator bool() const
-	{
-		return value;
-	}
-};
-
-#define ENUM(Name) struct Name : public BasicEnum<Name>
-#define ENUM_MEMBERS()                \
-	enum Enum : int;                  \
-	operator Enum() const             \
-	{                                 \
-		return (Enum)value;           \
-	}                                 \
-	using BasicEnum<Self>::BasicEnum; \
-	enum Enum : int
-
-template <class TSelf>
-struct BasicFlag
-{
-	using Self = TSelf;
-	using ValueType = int;
-
-	int value;
-
-	BasicFlag()
-		: value{ 0 } {}
-	BasicFlag(int value)
-		: value{ value } {}
-
-	bool IsSet(TSelf mask) const
-	{
-		return (value & mask.value) == mask.value;
-	}
-	bool IsSetExclusive(TSelf mask) const
-	{
-		return value == mask.value;
-	}
-	void Set(TSelf mask, bool state)
-	{
-		if (state) {
-			value = (int)(value | mask.value);
-		} else {
-			value = (int)(value & ~mask.value);
-		}
-	}
-
-	/// Comparsion between 2 values of flag. Useful for situations like `a == b` where both a and b are TSelf.
-	friend bool operator==(const TSelf& a, const TSelf& b)
-	{
-		return a.value == b.value;
-	}
-
-	friend auto operator<=>(const TSelf& a, const TSelf& b)
-	{
-		return a.value <=> b.value;
-	}
-
-	/// Comparsion between a flag and a raw value. Useful for situations like `a == TSelf::Option` where a is a flag and TSelf::Option is a raw value.
-	friend bool operator==(const TSelf& self, int value)
-	{
-		return self.value == value;
-	}
-
-	friend auto operator<=>(const TSelf& self, int value)
-	{
-		return self.value <=> value;
-	}
-
-	friend TSelf operator&(const TSelf& a, const TSelf& b)
-	{
-		return TSelf(a.value & b.value);
-	}
-
-	friend TSelf operator|(const TSelf& a, const TSelf& b)
-	{
-		return TSelf(a.value | b.value);
-	}
-
-	friend TSelf operator^(const TSelf& a, const TSelf& b)
-	{
-		return TSelf(a.value ^ b.value);
-	}
-
-	TSelf operator~() const
-	{
-		return TSelf(~value);
-	}
-
-	TSelf& operator&=(int that)
-	{
-		value = value & that;
-		return *this;
-	}
-
-	TSelf& operator|=(int that)
-	{
-		value = value | that;
-		return *this;
-	}
-
-	TSelf& operator^=(int that)
-	{
-		value = value ^ that;
-		return *this;
-	}
-};
diff --git a/core/src/Utils/Macros.hpp b/core/src/Utils/Macros.hpp
index 658aebf..68b93fb 100644
--- a/core/src/Utils/Macros.hpp
+++ b/core/src/Utils/Macros.hpp
@@ -4,3 +4,5 @@
 #define CONCAT(a, b) CONCAT_IMPL(a, b)
 
 #define UNIQUE_NAME(prefix) CONCAT(prefix, __COUNTER__)
+#define UNIQUE_NAME_LINE(prefix) CONCAT(prefix, __LINE__)
+#define DISCARD UNIQUE_NAME(_discard)
diff --git a/core/src/Utils/Vector.hpp b/core/src/Utils/Vector.hpp
index 61fa520..bf75fd1 100644
--- a/core/src/Utils/Vector.hpp
+++ b/core/src/Utils/Vector.hpp
@@ -1,7 +1,64 @@
 #pragma once
 
-struct Vec2i
+template <class T>
+struct Vec2
 {
-	int x = 0;
-	int y = 0;
+	T x = 0;
+	T y = 0;
+
+	friend constexpr Vec2 operator+(const Vec2& a, const Vec2& b) { return { a.x + b.x, a.y + b.y }; }
+	friend constexpr Vec2 operator-(const Vec2& a, const Vec2& b) { return { a.x - b.x, a.y - b.y }; }
+	friend constexpr Vec2 operator*(const Vec2& a, const Vec2& b) { return { a.x * b.x, a.y * b.y }; }
+	friend constexpr Vec2 operator/(const Vec2& a, const Vec2& b) { return { a.x / b.x, a.y / b.y }; }
+
+	friend constexpr Vec2 operator+(const Vec2& a, T n) { return { a.x + n, a.y + n }; }
+	friend constexpr Vec2 operator-(const Vec2& a, T n) { return { a.x - n, a.y - n }; }
+	friend constexpr Vec2 operator*(const Vec2& a, T n) { return { a.x * n, a.y * n }; }
+	friend constexpr Vec2 operator/(const Vec2& a, T n) { return { a.x / n, a.y / n }; }
+};
+
+using Vec2i = Vec2<int>;
+using Vec2f = Vec2<float>;
+
+template <class T>
+struct Vec3
+{
+	T x = 0;
+	T y = 0;
+	T z = 0;
+
+	friend constexpr Vec3 operator+(const Vec3& a, const Vec3& b) { return { a.x + b.x, a.y + b.y, a.z + b.z }; }
+	friend constexpr Vec3 operator-(const Vec3& a, const Vec3& b) { return { a.x - b.x, a.y - b.y, a.z - b.z }; }
+	friend constexpr Vec3 operator*(const Vec3& a, const Vec3& b) { return { a.x * b.x, a.y * b.y, a.z * b.z }; }
+	friend constexpr Vec3 operator/(const Vec3& a, const Vec3& b) { return { a.x / b.x, a.y / b.y, a.z / b.z }; }
+
+	friend constexpr Vec3 operator+(const Vec3& a, T n) { return { a.x + n, a.y + n, a.z + n }; }
+	friend constexpr Vec3 operator-(const Vec3& a, T n) { return { a.x - n, a.y - n, a.z - n }; }
+	friend constexpr Vec3 operator*(const Vec3& a, T n) { return { a.x * n, a.y * n, a.z * n }; }
+	friend constexpr Vec3 operator/(const Vec3& a, T n) { return { a.x / n, a.y / n, a.z / n }; }
 };
+
+using Vec3i = Vec3<int>;
+using Vec3f = Vec3<float>;
+
+template <class T>
+struct Vec4
+{
+	T x = 0;
+	T y = 0;
+	T z = 0;
+	T w = 0;
+
+	friend constexpr Vec4 operator+(const Vec4& a, const Vec4& b) { return { a.x + b.x, a.y + b.y, a.z + b.z, a.w + b.w }; }
+	friend constexpr Vec4 operator-(const Vec4& a, const Vec4& b) { return { a.x - b.x, a.y - b.y, a.z - b.z, a.w - b.w }; }
+	friend constexpr Vec4 operator*(const Vec4& a, const Vec4& b) { return { a.x * b.x, a.y * b.y, a.z * b.z, a.w * b.w }; }
+	friend constexpr Vec4 operator/(const Vec4& a, const Vec4& b) { return { a.x / b.x, a.y / b.y, a.z / b.z, a.w / b.w }; }
+
+	friend constexpr Vec4 operator+(const Vec4& a, T n) { return { a.x + n, a.y + n, a.z + n, a.w + n }; }
+	friend constexpr Vec4 operator-(const Vec4& a, T n) { return { a.x - n, a.y - n, a.z - n, a.w - n }; }
+	friend constexpr Vec4 operator*(const Vec4& a, T n) { return { a.x * n, a.y * n, a.z * n, a.w * n }; }
+	friend constexpr Vec4 operator/(const Vec4& a, T n) { return { a.x / n, a.y / n, a.z / n, a.w / n }; }
+};
+
+using Vec4i = Vec4<int>;
+using Vec4f = Vec4<float>;
diff --git a/core/src/Utils/fwd.hpp b/core/src/Utils/fwd.hpp
index 58b2991..74e642d 100644
--- a/core/src/Utils/fwd.hpp
+++ b/core/src/Utils/fwd.hpp
@@ -1,10 +1,8 @@
 #pragma once
 
-// Sigslot.hpp
-class SignalStub;
-template <class... TArgs>
-class Signal;
-class SlotGuard;
+// Color.hpp
+class RgbaColor;
+class HsvColor;
 
 // I18n.hpp
 class I18n;
@@ -15,6 +13,12 @@ class BasicTranslation;
 class FormattedTranslation;
 class NumericTranslation;
 
+// Sigslot.hpp
+class SignalStub;
+template <class... TArgs>
+class Signal;
+class SlotGuard;
+
 // String.hpp
 class Utf8Iterator;
 class Utf8IterableString;