Second prototype of standalone node graph editor for ImGui

nodes.cpp

#include "nodes.h"

namespace ImGui
{
	void ImGuiNodes::UpdateCanvasGeometry(ImDrawList* draw_list)
	{
		const ImGuiIO& io = ImGui::GetIO();

		mouse_ = ImGui::GetMousePos();

		{
			ImVec2 min = ImGui::GetWindowContentRegionMin();
			ImVec2 max = ImGui::GetWindowContentRegionMax();

			pos_ = ImGui::GetWindowPos() + min;
			size_ = max - min;	
		}

		ImRect canvas(pos_, pos_ + size_);

		////////////////////////////////////////////////////////////////////////////////

		if (ImGui::IsKeyPressed(io.KeyMap[ImGuiKey_Home]))
		{
			scroll_ = {};
			scale_ = 1.0f;
		}
				
		////////////////////////////////////////////////////////////////////////////////

		if (false == ImGui::IsMouseDown(0) && canvas.Contains(mouse_))
		{
			if (ImGui::IsMouseDragging(1))
				scroll_ += io.MouseDelta;

			if (io.KeyShift && !io.KeyCtrl)
				scroll_.x += io.MouseWheel * 16.0f;

			if (!io.KeyShift && !io.KeyCtrl)
				scroll_.y += io.MouseWheel * 16.0f;

			if (!io.KeyShift && io.KeyCtrl)
			{
				ImVec2 focus = (mouse_ - scroll_ - pos_) / scale_;

				if (io.MouseWheel < 0.0f)
					for (float zoom = io.MouseWheel; zoom < 0.0f; zoom += 1.0f)
						scale_ = ImMax(0.3f, scale_ / 1.05f);

				if (io.MouseWheel > 0.0f)
					for (float zoom = io.MouseWheel; zoom > 0.0f; zoom -= 1.0f)
						scale_ = ImMin(3.0f, scale_ * 1.05f);

				ImVec2 shift = scroll_ + (focus * scale_);
				scroll_ += mouse_ - shift - pos_;
			}

			if (ImGui::IsMouseReleased(1) && element_node_ == NULL)
				if (io.MouseDragMaxDistanceSqr[1] < (io.MouseDragThreshold * io.MouseDragThreshold))
				{
					bool selected = false;

					for (int node_idx = 0; node_idx < nodes_.size(); ++node_idx)
					{
						if (nodes_[node_idx]->state_ & ImGuiNodesNodeStateFlag_Selected)
						{					
							selected = true;
							break;
						}
					}

					if (false == selected)
						ImGui::OpenPopup("NodesContextMenu");
				}
		}

		////////////////////////////////////////////////////////////////////////////////

		const float grid = 64.0f * scale_;
		
		int mark_x = (int)(scroll_.x / grid);
		for (float x = std::fmodf(scroll_.x, grid); x < size_.x; x += grid, --mark_x)
		{		
			ImColor color = mark_x % 5 ? ImColor(0.5f, 0.5f, 0.5f, 0.1f) : ImColor(1.0f, 1.0f, 1.0f, 0.1f);
			draw_list->AddLine(ImVec2(x, 0.0f) + pos_, ImVec2(x, size_.y) + pos_, color, 0.1f);	
		}
			
		int mark_y = (int)(scroll_.y / grid);
		for (float y = std::fmodf(scroll_.y, grid); y < size_.y; y += grid, --mark_y)
		{
			ImColor color = mark_y % 5 ? ImColor(0.5f, 0.5f, 0.5f, 0.1f) : ImColor(1.0f, 1.0f, 1.0f, 0.1f);
			draw_list->AddLine(ImVec2(0.0f, y) + pos_, ImVec2(size_.x, y) + pos_, color, 0.1f);
		}
	}

	ImGuiNodesNode* ImGuiNodes::UpdateNodesFromCanvas()
	{
		if (nodes_.empty())
			return NULL;

		const ImGuiIO& io = ImGui::GetIO();

		ImVec2 offset = pos_ + scroll_;
		ImRect canvas(pos_, pos_ + size_);
		ImGuiNodesNode* hovered_node = NULL;

		for (int node_idx = nodes_.size(); node_idx != 0;)
		{
			ImGuiNodesNode* node = nodes_[--node_idx];
			IM_ASSERT(node);

			ImRect node_rect = node->area_node_;
			node_rect.Min *= scale_;
			node_rect.Max *= scale_;
			node_rect.Translate(offset);

			node_rect.ClipWith(canvas);

			if (canvas.Overlaps(node_rect))
			{
				node->state_ |= ImGuiNodesNodeStateFlag_Visible;
				node->state_ &= ~ImGuiNodesNodeStateFlag_Hovered;
			}
			else
			{
				node->state_ &= ~(ImGuiNodesNodeStateFlag_Visible | ImGuiNodesNodeStateFlag_Hovered | ImGuiNodesNodeStateFlag_Marked);
				continue;
			}

			if (NULL == hovered_node && node_rect.Contains(mouse_))
				hovered_node = node;

			////////////////////////////////////////////////////////////////////////////////

			if (state_ == ImGuiNodesState_Selecting)
			{
				if (io.KeyCtrl && area_.Overlaps(node_rect))
				{
					node->state_ |= ImGuiNodesNodeStateFlag_Marked;
					continue;
				}

				if (false == io.KeyCtrl && area_.Contains(node_rect))
				{
					node->state_ |= ImGuiNodesNodeStateFlag_Marked;
					continue;
				}

				node->state_ &= ~ImGuiNodesNodeStateFlag_Marked;
			}

			////////////////////////////////////////////////////////////////////////////////

			for (int input_idx = 0; input_idx < node->inputs_.size(); ++input_idx)
			{
				ImGuiNodesInput& input = node->inputs_[input_idx];

				if (input.type_ == ImGuiNodesConnectorType_None)
					continue;

				input.state_ &= ~(ImGuiNodesConnectorStateFlag_Hovered | ImGuiNodesConnectorStateFlag_Consider | ImGuiNodesConnectorStateFlag_Draging);

				if (state_ == ImGuiNodesState_DragingInput)
				{
					if (&input == element_input_)
						input.state_ |= ImGuiNodesConnectorStateFlag_Draging;

					continue;
				}				

				if (state_ == ImGuiNodesState_DragingOutput)
				{
					if (element_node_ == node)
						continue;

					if (ConnectionMatrix(node, element_node_, &input, element_output_))
						input.state_ |= ImGuiNodesConnectorStateFlag_Consider;
				}

				if (!hovered_node || hovered_node != node)
					continue;

				if (state_ == ImGuiNodesState_Selecting)
					continue;

				if (state_ != ImGuiNodesState_DragingOutput && node->state_ & ImGuiNodesNodeStateFlag_Selected)
					continue;

				ImRect input_rect = input.area_input_;
				input_rect.Min *= scale_;
				input_rect.Max *= scale_;
				input_rect.Translate(offset);

				if (input_rect.Contains(mouse_))
				{
					if (state_ != ImGuiNodesState_DragingOutput)
					{
						input.state_ |= ImGuiNodesConnectorStateFlag_Hovered;
						continue;
					}
					
					if (input.state_ & ImGuiNodesConnectorStateFlag_Consider)
						input.state_ |= ImGuiNodesConnectorStateFlag_Hovered;
				}				
			}

			////////////////////////////////////////////////////////////////////////////////
			
			for (int output_idx = 0; output_idx < node->outputs_.size(); ++output_idx)
			{
				ImGuiNodesOutput& output = node->outputs_[output_idx];

				if (output.type_ == ImGuiNodesConnectorType_None)
					continue;

				output.state_ &= ~(ImGuiNodesConnectorStateFlag_Hovered | ImGuiNodesConnectorStateFlag_Consider | ImGuiNodesConnectorStateFlag_Draging);

				if (state_ == ImGuiNodesState_DragingOutput)
				{
					if (&output == element_output_)
						output.state_ |= ImGuiNodesConnectorStateFlag_Draging;

					continue;
				}

				if (state_ == ImGuiNodesState_DragingInput)
				{
					if (element_node_ == node)
						continue;

					if (ConnectionMatrix(element_node_, node, element_input_, &output))
						output.state_ |= ImGuiNodesConnectorStateFlag_Consider;
				}

				if (!hovered_node || hovered_node != node)
					continue;
			
				if (state_ == ImGuiNodesState_Selecting)
					continue;

				if (state_ != ImGuiNodesState_DragingInput && node->state_ & ImGuiNodesNodeStateFlag_Selected)
					continue;
				
				ImRect output_rect = output.area_output_;
				output_rect.Min *= scale_;
				output_rect.Max *= scale_;
				output_rect.Translate(offset);

				if (output_rect.Contains(mouse_))
				{
					if (state_ != ImGuiNodesState_DragingInput)
					{
						output.state_ |= ImGuiNodesConnectorStateFlag_Hovered;
						continue;
					}

					if (output.state_ & ImGuiNodesConnectorStateFlag_Consider)
						output.state_ |= ImGuiNodesConnectorStateFlag_Hovered;
				}
			}	
		}

		if (hovered_node)
			hovered_node->state_ |= ImGuiNodesNodeStateFlag_Hovered;

		return hovered_node;
	}

	ImGuiNodesNode* ImGuiNodes::CreateNodeFromDesc(ImGuiNodesNodeDesc* desc, ImVec2 pos)
	{
		IM_ASSERT(desc);
		ImGuiNodesNode* node = new ImGuiNodesNode(desc->name_, desc->type_, desc->color_);
		
		ImVec2 inputs;
		ImVec2 outputs;

		////////////////////////////////////////////////////////////////////////////////

		for (int input_idx = 0; input_idx < desc->inputs_.size(); ++input_idx)
		{
			ImGuiNodesInput input(desc->inputs_[input_idx].name_, desc->inputs_[input_idx].type_);

			inputs.x = ImMax(inputs.x, input.area_input_.GetWidth());
			inputs.y += input.area_input_.GetHeight();
			node->inputs_.push_back(input);
		}

		for (int output_idx = 0; output_idx < desc->outputs_.size(); ++output_idx)
		{
			ImGuiNodesOutput output(desc->outputs_[output_idx].name_, desc->outputs_[output_idx].type_);
		
			outputs.x = ImMax(outputs.x, output.area_output_.GetWidth());
			outputs.y += output.area_output_.GetHeight();
			node->outputs_.push_back(output);
		}

		////////////////////////////////////////////////////////////////////////////////
		
		node->BuildNodeGeometry(inputs, outputs);
		node->TranslateNode(pos - node->area_node_.GetCenter());
		node->state_ |= ImGuiNodesNodeStateFlag_Visible | ImGuiNodesNodeStateFlag_Hovered | ImGuiNodesNodeStateFlag_Processing;

		////////////////////////////////////////////////////////////////////////////////

		if (processing_node_)
			processing_node_->state_ &= ~(ImGuiNodesNodeStateFlag_Processing);

		return processing_node_ = node;
	}

	bool ImGuiNodes::SortSelectedNodesOrder()
	{
		bool selected = false;

		ImVector<ImGuiNodesNode*> nodes_unselected;
		nodes_unselected.reserve(nodes_.size());

		ImVector<ImGuiNodesNode*> nodes_selected;
		nodes_selected.reserve(nodes_.size());

		for (ImGuiNodesNode** iterator = nodes_.begin(); iterator != nodes_.end(); ++iterator)
		{
			ImGuiNodesNode* node = ((ImGuiNodesNode*)*iterator);

			if (node->state_ & ImGuiNodesNodeStateFlag_Marked || node->state_ & ImGuiNodesNodeStateFlag_Selected)
			{
				selected = true;
				node->state_ &= ~ImGuiNodesNodeStateFlag_Marked;
				node->state_ |= ImGuiNodesNodeStateFlag_Selected;
				nodes_selected.push_back(node);
			}
			else
				nodes_unselected.push_back(node);
		}

		int node_idx = 0;

		for (int unselected_idx = 0; unselected_idx < nodes_unselected.size(); ++unselected_idx)
			nodes_[node_idx++] = nodes_unselected[unselected_idx];

		for (int selected_idx = 0; selected_idx < nodes_selected.size(); ++selected_idx)
			nodes_[node_idx++] = nodes_selected[selected_idx];

		return selected;
	}

	void ImGuiNodes::Update()
	{
		const ImGuiIO& io = ImGui::GetIO();
		
		UpdateCanvasGeometry(ImGui::GetWindowDrawList());

		////////////////////////////////////////////////////////////////////////////////

		ImGuiNodesNode* hovered_node = UpdateNodesFromCanvas();

		bool consider_hover = state_ == ImGuiNodesState_Default;
		consider_hover |= state_ == ImGuiNodesState_HoveringNode;
		consider_hover |= state_ == ImGuiNodesState_HoveringInput;
		consider_hover |= state_ == ImGuiNodesState_HoveringOutput;

		////////////////////////////////////////////////////////////////////////////////

		if (hovered_node && consider_hover)
		{
			element_input_ = NULL;
			element_output_ = NULL;

			for (int input_idx = 0; input_idx < hovered_node->inputs_.size(); ++input_idx)
			{
				if (hovered_node->inputs_[input_idx].state_ & ImGuiNodesConnectorStateFlag_Hovered)
				{
					element_input_ = &hovered_node->inputs_[input_idx];
					state_ = ImGuiNodesState_HoveringInput;
					break;
				}
			}						
			
			for (int output_idx = 0; output_idx < hovered_node->outputs_.size(); ++output_idx)
			{
				if (hovered_node->outputs_[output_idx].state_ & ImGuiNodesConnectorStateFlag_Hovered)
				{
					element_output_ = &hovered_node->outputs_[output_idx];
					state_ = ImGuiNodesState_HoveringOutput;
					break;
				}
			}					

			if (!element_input_ && !element_output_)
				state_ = ImGuiNodesState_HoveringNode;	
		}

		////////////////////////////////////////////////////////////////////////////////

		if (state_ == ImGuiNodesState_DragingInput)
		{
			element_output_ = NULL;
		
			if (hovered_node)
				for (int output_idx = 0; output_idx < hovered_node->outputs_.size(); ++output_idx)
				{
					ImGuiNodesConnectorState state = hovered_node->outputs_[output_idx].state_;

					if (state & ImGuiNodesConnectorStateFlag_Hovered && state & ImGuiNodesConnectorStateFlag_Consider)
						element_output_ = &hovered_node->outputs_[output_idx];
				}
		}
		
		if (state_ == ImGuiNodesState_DragingOutput)
		{
			element_input_ = NULL;
		
			if (hovered_node)
				for (int input_idx = 0; input_idx < hovered_node->inputs_.size(); ++input_idx)
				{
					ImGuiNodesConnectorState state = hovered_node->inputs_[input_idx].state_;

					if (state & ImGuiNodesConnectorStateFlag_Hovered && state & ImGuiNodesConnectorStateFlag_Consider)
						element_input_ = &hovered_node->inputs_[input_idx];
				}
		}

		////////////////////////////////////////////////////////////////////////////////

		if (consider_hover)
		{
			element_node_ = hovered_node;

			if (!hovered_node)
				state_ = ImGuiNodesState_Default;
		}					

		////////////////////////////////////////////////////////////////////////////////
	
		if (ImGui::IsMouseDoubleClicked(0))
		{
			switch (state_)
			{
				case ImGuiNodesState_Default:
				{
					bool selected = false;

					for (int node_idx = 0; node_idx < nodes_.size(); ++node_idx)
					{
					    ImGuiNodesState& state = nodes_[node_idx]->state_;

					    if (state & ImGuiNodesNodeStateFlag_Selected)
						    selected = true;

						state &= ~(ImGuiNodesNodeStateFlag_Selected | ImGuiNodesNodeStateFlag_Marked | ImGuiNodesNodeStateFlag_Hovered);
					}

					if (processing_node_ && false == selected)
					{
						processing_node_->state_ &= ~(ImGuiNodesNodeStateFlag_Processing);
						processing_node_ = NULL;
					}				  

					return;
				};
	
				case ImGuiNodesState_HoveringInput:
			    {
					if (element_input_->target_)
					{
						element_input_->output_->connections_--;
					    element_input_->output_ = NULL;
						element_input_->target_ = NULL;

						state_ = ImGuiNodesState_DragingInput;
					}

					return;
				}

				case ImGuiNodesState_HoveringNode:
				{
				    IM_ASSERT(element_node_);

					if (element_node_->state_ & ImGuiNodesNodeStateFlag_Collapsed)
					{					
						element_node_->state_ &= ~ImGuiNodesNodeStateFlag_Collapsed;
						element_node_->area_node_.Max.y += element_node_->body_height_;
						element_node_->TranslateNode(ImVec2(0.0f, element_node_->body_height_ * -0.5f));
					}
					else
					{
						element_node_->state_ |= ImGuiNodesNodeStateFlag_Collapsed;
						element_node_->area_node_.Max.y -= element_node_->body_height_;

						//const ImVec2 click = (mouse_ - scroll_ - pos_) / scale_;
					    //const ImVec2 position = click - element_node_->area_node_.GetCenter();

						element_node_->TranslateNode(ImVec2(0.0f, element_node_->body_height_ * 0.5f));
					}
	
					state_ = ImGuiNodesState_Draging;
					return;
				}
			}
		}

		////////////////////////////////////////////////////////////////////////////////
		
		if (ImGui::IsMouseDoubleClicked(1))
		{
			switch (state_)
			{
				case ImGuiNodesState_HoveringNode:
				{
					IM_ASSERT(hovered_node);

					if (hovered_node->state_ & ImGuiNodesNodeStateFlag_Disabled)
						hovered_node->state_ &= ~(ImGuiNodesNodeStateFlag_Disabled);
					else
						hovered_node->state_ |= (ImGuiNodesNodeStateFlag_Disabled);

					return;
				}
			}
		}

		////////////////////////////////////////////////////////////////////////////////

		if (ImGui::IsMouseClicked(0))
		{
			switch (state_)
			{				
				case ImGuiNodesState_HoveringNode:
				{
					if (io.KeyCtrl)
						element_node_->state_ ^= ImGuiNodesNodeStateFlag_Selected;

					if (io.KeyShift)
						element_node_->state_ |= ImGuiNodesNodeStateFlag_Selected;

					bool selected = element_node_->state_ & ImGuiNodesNodeStateFlag_Selected;

					if (false == selected)
					{
						if (processing_node_)
							processing_node_->state_ &= ~(ImGuiNodesNodeStateFlag_Processing);

						element_node_->state_ |= ImGuiNodesNodeStateFlag_Processing;
						processing_node_ = element_node_;

						IM_ASSERT(false == nodes_.empty());

						if (nodes_.back() != element_node_)
					    {
							ImGuiNodesNode** iterator = nodes_.find(element_node_);
						    nodes_.erase(iterator);
							nodes_.push_back(element_node_);
						}
					}
					else
						SortSelectedNodesOrder();
	
					state_ = ImGuiNodesState_Draging;
					return;
				}
	
				case ImGuiNodesState_HoveringInput:
				{
					if (!element_input_->target_)
						state_ = ImGuiNodesState_DragingInput;
					else
						state_ = ImGuiNodesState_Draging;

					return;
				}
	
				case ImGuiNodesState_HoveringOutput:
				{
					state_ = ImGuiNodesState_DragingOutput;
					return;
				}
			}

			return;
		}

		////////////////////////////////////////////////////////////////////////////////
	
		if (ImGui::IsMouseDragging(0))
		{
			switch (state_)
			{
				case ImGuiNodesState_Default:
				{
					ImRect canvas(pos_, pos_ + size_);
					if (false == canvas.Contains(mouse_))
						return;
	
					if (false == io.KeyShift)
						for (int node_idx = 0; node_idx < nodes_.size(); ++node_idx)
							nodes_[node_idx]->state_ &= ~(ImGuiNodesNodeStateFlag_Selected | ImGuiNodesNodeStateFlag_Marked);
	
					state_ = ImGuiNodesState_Selecting;
					return;
				}
	
				case ImGuiNodesState_Selecting:
				{
					const ImVec2 pos = mouse_ - ImGui::GetMouseDragDelta(0);
	
					area_.Min = ImMin(pos, mouse_);
					area_.Max = ImMax(pos, mouse_);
	
					return;
				}
	
				case ImGuiNodesState_Draging:
				{
					if (element_input_ && element_input_->output_ && element_input_->output_->connections_ > 0)
				        return;

					if (false == (element_node_->state_ & ImGuiNodesNodeStateFlag_Selected))
						element_node_->TranslateNode(io.MouseDelta / scale_, false);
					else
						for (int node_idx = 0; node_idx < nodes_.size(); ++node_idx)
							nodes_[node_idx]->TranslateNode(io.MouseDelta / scale_, true);
	
					return;
				}
	
				case ImGuiNodesState_DragingInput:
				{
					ImVec2 offset = pos_ + scroll_;
					ImVec2 p1 = offset + (element_input_->pos_ * scale_);
					ImVec2 p4 = element_output_ ? (offset + (element_output_->pos_ * scale_)) : mouse_;
	
					connection_ = ImVec4(p1.x, p1.y, p4.x, p4.y);
					return;
				}
	
				case ImGuiNodesState_DragingOutput:
				{
					ImVec2 offset = pos_ + scroll_;
					ImVec2 p1 = offset + (element_output_->pos_ * scale_);
					ImVec2 p4 = element_input_ ? (offset + (element_input_->pos_ * scale_)) : mouse_;

					connection_ = ImVec4(p4.x, p4.y, p1.x, p1.y);
					return;
				}
			}
	
			return;
		}
	
		////////////////////////////////////////////////////////////////////////////////

		if (ImGui::IsMouseReleased(0))
		{
			switch (state_)
			{
			case ImGuiNodesState_Selecting:
			{
				element_node_ = NULL;
				element_input_ = NULL;
				element_output_ = NULL;

				area_ = {};

				////////////////////////////////////////////////////////////////////////////////

				SortSelectedNodesOrder();
				state_ = ImGuiNodesState_Default;
				return;
			}

			case ImGuiNodesState_Draging:
			{
				state_ = ImGuiNodesState_HoveringNode;
				return;
			}

			case ImGuiNodesState_DragingInput:
			case ImGuiNodesState_DragingOutput:
			{
				if (element_input_ && element_output_)
				{
					IM_ASSERT(hovered_node);
					IM_ASSERT(element_node_);
					element_input_->target_ = state_ == ImGuiNodesState_DragingInput ? hovered_node : element_node_;

					if (element_input_->output_)
						element_input_->output_->connections_--;

					element_input_->output_ = element_output_;
					element_output_->connections_++;
				}

				connection_ = ImVec4();
				state_ = ImGuiNodesState_Default;
				return;
			}
			}

			return;
		}

		////////////////////////////////////////////////////////////////////////////////
		
		if (ImGui::IsKeyPressed(io.KeyMap[ImGuiKey_Delete]))
		{
			ImVector<ImGuiNodesNode*> nodes;
			nodes.reserve(nodes_.size());

			for (int node_idx = 0; node_idx < nodes_.size(); ++node_idx)
			{
				ImGuiNodesNode* node = nodes_[node_idx];
				IM_ASSERT(node);

				if (node->state_ & ImGuiNodesNodeStateFlag_Selected)
				{
					element_node_ = NULL;
					element_input_ = NULL;
					element_output_ = NULL;

					state_ = ImGuiNodesState_Default;

					for (int sweep_idx = 0; sweep_idx < nodes_.size(); ++sweep_idx)
					{
						ImGuiNodesNode* sweep = nodes_[sweep_idx];
						IM_ASSERT(sweep);
					
						for (int input_idx = 0; input_idx < sweep->inputs_.size(); ++input_idx)
						{
							ImGuiNodesInput& input = sweep->inputs_[input_idx];

							if (node == input.target_)
							{
								if (input.output_)
									input.output_->connections_--;

								input.target_ = NULL;
								input.output_ = NULL;
							}
						}
					}

					for (int input_idx = 0; input_idx < node->inputs_.size(); ++input_idx)
					{
						ImGuiNodesInput& input = node->inputs_[input_idx];
						
						if (input.output_)
							input.output_->connections_--;
						
						input.type_ = ImGuiNodesNodeType_None;
						input.name_ = NULL;
						input.target_ = NULL;
						input.output_ = NULL;
					}

					for (int output_idx = 0; output_idx < node->outputs_.size(); ++output_idx)
					{
						ImGuiNodesOutput& output = node->outputs_[output_idx];
						IM_ASSERT(output.connections_ == 0);
					}

					if (node == processing_node_)
						processing_node_ = NULL;
		
					delete node;
				}
				else
				{
					nodes.push_back(node);
				}			
			}

			nodes_ = nodes;

			return;
		}
	}

	void ImGuiNodes::ProcessNodes()
	{
		ImDrawList* draw_list = ImGui::GetWindowDrawList();

		const ImVec2 offset = pos_ + scroll_;

		////////////////////////////////////////////////////////////////////////////////

		ImGui::SetWindowFontScale(scale_);

		for (int node_idx = 0; node_idx < nodes_.size(); ++node_idx)
		{
			const ImGuiNodesNode* node = nodes_[node_idx];
			IM_ASSERT(node);

			for (int input_idx = 0; input_idx < node->inputs_.size(); ++input_idx)
			{		
				const ImGuiNodesInput& input = node->inputs_[input_idx];
				
				if (const ImGuiNodesNode* target = input.target_)
				{
					IM_ASSERT(target);

					ImVec2 p1 = offset;
					ImVec2 p4 = offset;

					if (node->state_ & ImGuiNodesNodeStateFlag_Collapsed)
					{
						ImVec2 collapsed_input = { 0, (node->area_node_.Max.y - node->area_node_.Min.y) * 0.5f };					

						p1 += ((node->area_node_.Min + collapsed_input) * scale_);
					}
					else
					{
						p1 += (input.pos_ * scale_);
					}

					if (target->state_ & ImGuiNodesNodeStateFlag_Collapsed)
					{
						ImVec2 collapsed_output = { 0, (target->area_node_.Max.y - target->area_node_.Min.y) * 0.5f };					
						
						p4 += ((target->area_node_.Max - collapsed_output) * scale_);
					}
					else
					{
						p4 += (input.output_->pos_ * scale_);		
					}

					DrawConnection(p1, p4, ImColor(1.0f, 1.0f, 1.0f, 1.0f));
				}
			}
		}

		for (int node_idx = 0; node_idx < nodes_.size(); ++node_idx)
		{
			const ImGuiNodesNode* node = nodes_[node_idx];
			IM_ASSERT(node);
			node->DrawNode(draw_list, offset, scale_, state_);
		}

		if (connection_.x != connection_.z && connection_.y != connection_.w)
			DrawConnection(ImVec2(connection_.x, connection_.y), ImVec2(connection_.z, connection_.w), ImColor(0.0f, 1.0f, 0.0f, 1.0f));

		ImGui::SetWindowFontScale(1.0f);

		////////////////////////////////////////////////////////////////////////////////

		if (state_ == ImGuiNodesState_Selecting)
		{
			draw_list->AddRectFilled(area_.Min, area_.Max, ImColor(1.0f, 1.0f, 0.0f, 0.1f));
			draw_list->AddRect(area_.Min, area_.Max, ImColor(1.0f, 1.0f, 0.0f, 0.5f));
		}

		////////////////////////////////////////////////////////////////////////////////

		ImGui::SetCursorPos(ImVec2(0.0f, 0.0f));
		ImGui::NewLine();
		
		switch (state_)
		{
			case ImGuiNodesState_Default: ImGui::Text("ImGuiNodesState_Default"); break;
			case ImGuiNodesState_HoveringNode: ImGui::Text("ImGuiNodesState_HoveringNode"); break;
			case ImGuiNodesState_HoveringInput: ImGui::Text("ImGuiNodesState_HoveringInput"); break;
			case ImGuiNodesState_HoveringOutput: ImGui::Text("ImGuiNodesState_HoveringOutput"); break;
			case ImGuiNodesState_Draging: ImGui::Text("ImGuiNodesState_Draging"); break;
			case ImGuiNodesState_DragingInput: ImGui::Text("ImGuiNodesState_DragingInput"); break;
			case ImGuiNodesState_DragingOutput: ImGui::Text("ImGuiNodesState_DragingOutput"); break;
			case ImGuiNodesState_Selecting: ImGui::Text("ImGuiNodesState_Selecting"); break;
			default: ImGui::Text("UNKNOWN"); break;
		}

		ImGui::NewLine();

		ImGui::Text("Position: %.2f, %.2f", pos_.x, pos_.y);
		ImGui::Text("Size: %.2f, %.2f", size_.x, size_.y);
		ImGui::Text("Mouse: %.2f, %.2f", mouse_.x, mouse_.y);
		ImGui::Text("Scroll: %.2f, %.2f", scroll_.x, scroll_.y);
		ImGui::Text("Scale: %.2f", scale_);
	
		ImGui::NewLine();
		
		if (element_node_)
			ImGui::Text("Element_node: %s", element_node_->name_);
		if (element_input_)
			ImGui::Text("Element_input: %s", element_input_->name_);
		if (element_output_)
			ImGui::Text("Element_output: %s", element_output_->name_);


		////////////////////////////////////////////////////////////////////////////////
	}

	void ImGuiNodes::ProcessContextMenu()
	{
		ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(8, 8));

		if (ImGui::BeginPopup("NodesContextMenu"))
		{
			for (int node_idx = 0; node_idx < nodes_desc_.size(); ++node_idx)
				if (ImGui::MenuItem(nodes_desc_[node_idx].name_))
				{
					ImVec2 position = (mouse_ - scroll_ - pos_) / scale_;
					ImGuiNodesNode* node = CreateNodeFromDesc(&nodes_desc_[node_idx], position);
					nodes_.push_back(node);
				}

			ImGui::EndPopup();
		}

		ImGui::PopStyleVar();
	}
}

nodes.h

#pragma once

#define IMGUI_DEFINE_MATH_OPERATORS

#include "imgui.h"
#include "imgui_internal.h"

namespace ImGui
{
	////////////////////////////////////////////////////////////////////////////////

	enum ImGuiNodesConnectorType_
	{
		ImGuiNodesConnectorType_None = 0,
		ImGuiNodesConnectorType_Generic,
		ImGuiNodesConnectorType_Int,
		ImGuiNodesConnectorType_Float, 
		ImGuiNodesConnectorType_Vector,
		ImGuiNodesConnectorType_Image,
		ImGuiNodesConnectorType_Text
	};

	enum ImGuiNodesNodeType_
	{
		ImGuiNodesNodeType_None = 0,
		ImGuiNodesNodeType_Generic,
		ImGuiNodesNodeType_Generator,
		ImGuiNodesNodeType_Test
	};

	enum ImGuiNodesConnectorStateFlag_
	{
		ImGuiNodesConnectorStateFlag_Default	= 0,
		ImGuiNodesConnectorStateFlag_Visible	= 1 << 0,
		ImGuiNodesConnectorStateFlag_Hovered	= 1 << 1,
		ImGuiNodesConnectorStateFlag_Consider	= 1 << 2,
		ImGuiNodesConnectorStateFlag_Draging	= 1 << 3
	};

	enum ImGuiNodesNodeStateFlag_
	{
		ImGuiNodesNodeStateFlag_Default			= 0,
		ImGuiNodesNodeStateFlag_Visible			= 1 << 0,
		ImGuiNodesNodeStateFlag_Hovered			= 1 << 1,
		ImGuiNodesNodeStateFlag_Marked			= 1 << 2,
		ImGuiNodesNodeStateFlag_Selected		= 1 << 3,
		ImGuiNodesNodeStateFlag_Collapsed		= 1 << 4,
		ImGuiNodesNodeStateFlag_Disabled		= 1 << 5,
		ImGuiNodesNodeStateFlag_Processing		= 1 << 6 
	};

	enum ImGuiNodesState_
	{
		ImGuiNodesState_Default	= 0,
		ImGuiNodesState_HoveringNode,
		ImGuiNodesState_HoveringInput,
		ImGuiNodesState_HoveringOutput,
		ImGuiNodesState_Draging,
		ImGuiNodesState_DragingInput,
		ImGuiNodesState_DragingOutput,
		ImGuiNodesState_Selecting
	};

	////////////////////////////////////////////////////////////////////////////////

	typedef unsigned int ImGuiNodesConnectorType;
	typedef unsigned int ImGuiNodesNodeType;

	typedef unsigned int ImGuiNodesConnectorState;
	typedef unsigned int ImGuiNodesNodeState;

	typedef unsigned int ImGuiNodesState;

	////////////////////////////////////////////////////////////////////////////////

	// connector text name heights factors
	constexpr float ImGuiNodesConnectorDotDiameter = 0.7f; // connectors dot diameter
	constexpr float ImGuiNodesConnectorDotPadding = 0.35f; // connectors dot left/right sides padding
	constexpr float ImGuiNodesConnectorDistance = 1.5f; // vertical distance between connectors centers
	
	// title text name heights factors
	constexpr float ImGuiNodesHSeparation = 1.7f; // extra horizontal separation inbetween IOs
	constexpr float ImGuiNodesVSeparation = 1.5f; // total IOs area separation from title and node bottom edge
	constexpr float ImGuiNodesTitleHight = 2.0f;

	struct ImGuiNodesNode;
	struct ImGuiNodesInput;
	struct ImGuiNodesOutput;

	////////////////////////////////////////////////////////////////////////////////

	struct ImGuiNodesInput
	{
		ImVec2 pos_;
		ImRect area_input_;
		ImRect area_name_;
		ImGuiNodesConnectorType type_;
		ImGuiNodesConnectorState state_;
		const char* name_;
		ImGuiNodesNode* target_;
		ImGuiNodesOutput* output_;

		inline void TranslateInput(ImVec2 delta)
		{
			pos_ += delta;
			area_input_.Translate(delta);
			area_name_.Translate(delta);
		}

		inline void DrawInput(ImDrawList* draw_list, ImVec2 offset, float scale, ImGuiNodesState state) const
		{
			if (type_ == ImGuiNodesConnectorType_None)
				return;

			if (state != ImGuiNodesState_Draging && state_ & ImGuiNodesConnectorStateFlag_Hovered && false == (state_ & ImGuiNodesConnectorStateFlag_Consider))
			{
				const ImColor color = target_ == NULL ? ImColor(0.0f, 0.0f, 1.0f, 0.5f) : ImColor(1.0f, 0.5f, 0.0f, 0.5f);
				draw_list->AddRectFilled((area_input_.Min * scale) + offset, (area_input_.Max * scale) + offset, color);
			}

			if (state_ & (ImGuiNodesConnectorStateFlag_Consider | ImGuiNodesConnectorStateFlag_Draging))
				draw_list->AddRectFilled((area_input_.Min * scale) + offset, (area_input_.Max * scale) + offset, ImColor(0.0f, 1.0f, 0.0f, 0.5f));

			bool consider_fill = false;
			consider_fill |= bool(state_ & ImGuiNodesConnectorStateFlag_Draging);
			consider_fill |= bool(state_ & ImGuiNodesConnectorStateFlag_Hovered && state_ & ImGuiNodesConnectorStateFlag_Consider);

			ImColor color = consider_fill ? ImColor(0.0f, 1.0f, 0.0f, 1.0f) : ImColor(1.0f, 1.0f, 1.0f, 1.0f);
					
			consider_fill |= bool(target_);

			if (consider_fill)
				draw_list->AddCircleFilled((pos_ * scale) + offset, (ImGuiNodesConnectorDotDiameter * 0.5f) * area_name_.GetHeight() * scale, color);
			else
				draw_list->AddCircle((pos_ * scale) + offset, (ImGuiNodesConnectorDotDiameter * 0.5f) * area_name_.GetHeight() * scale, color);

			ImGui::SetCursorScreenPos((area_name_.Min * scale) + offset);
			ImGui::Text(name_);

		}

		ImGuiNodesInput(const char* name, ImGuiNodesConnectorType type)
		{
			type_ = type;
			state_ = ImGuiNodesConnectorStateFlag_Default;
			target_ = NULL;
			output_ = NULL;
			name_ = name;

			area_name_.Min = ImVec2(0.0f, 0.0f);
			area_name_.Max = ImGui::CalcTextSize(name);

			area_input_.Min = ImVec2(0.0f, 0.0f);
			area_input_.Max.x = ImGuiNodesConnectorDotPadding + ImGuiNodesConnectorDotDiameter + ImGuiNodesConnectorDotPadding;
			area_input_.Max.y = ImGuiNodesConnectorDistance;
			area_input_.Max *= area_name_.GetHeight();

			ImVec2 offset = ImVec2(0.0f, 0.0f) - area_input_.GetCenter();

			area_name_.Translate(ImVec2(area_input_.GetWidth(), (area_input_.GetHeight() - area_name_.GetHeight()) * 0.5f));

			area_input_.Max.x += area_name_.GetWidth();
			area_input_.Max.x += ImGuiNodesConnectorDotPadding * area_name_.GetHeight();

			area_input_.Translate(offset);
			area_name_.Translate(offset);
		}
	};

	struct ImGuiNodesOutput
	{
		ImVec2 pos_;
		ImRect area_output_;
		ImRect area_name_;
		ImGuiNodesConnectorType type_;
		ImGuiNodesConnectorState state_;
		const char* name_;
		unsigned int connections_;

		inline void TranslateOutput(ImVec2 delta)
		{
			pos_ += delta;
			area_output_.Translate(delta);
			area_name_.Translate(delta);
		}

		inline void DrawOutput(ImDrawList* draw_list, ImVec2 offset, float scale, ImGuiNodesState state) const
		{
			if (type_ == ImGuiNodesConnectorType_None)
				return;

			if (state != ImGuiNodesState_Draging && state_ & ImGuiNodesConnectorStateFlag_Hovered && false == (state_ & ImGuiNodesConnectorStateFlag_Consider))
				draw_list->AddRectFilled((area_output_.Min * scale) + offset, (area_output_.Max * scale) + offset, ImColor(0.0f, 0.0f, 1.0f, 0.5f));

			if (state_ & (ImGuiNodesConnectorStateFlag_Consider | ImGuiNodesConnectorStateFlag_Draging))
				draw_list->AddRectFilled((area_output_.Min * scale) + offset, (area_output_.Max * scale) + offset, ImColor(0.0f, 1.0f, 0.0f, 0.5f));

			bool consider_fill = false;
			consider_fill |= bool(state_ & ImGuiNodesConnectorStateFlag_Draging);
			consider_fill |= bool(state_ & ImGuiNodesConnectorStateFlag_Hovered && state_ & ImGuiNodesConnectorStateFlag_Consider);

			ImColor color = consider_fill ? ImColor(0.0f, 1.0f, 0.0f, 1.0f) : ImColor(1.0f, 1.0f, 1.0f, 1.0f);

			consider_fill |= bool(connections_ > 0);

			if (consider_fill)
				draw_list->AddCircleFilled((pos_ * scale) + offset, (ImGuiNodesConnectorDotDiameter * 0.5f) * area_name_.GetHeight() * scale, color);
			else
				draw_list->AddCircle((pos_ * scale) + offset, (ImGuiNodesConnectorDotDiameter * 0.5f) * area_name_.GetHeight() * scale, color);

			ImGui::SetCursorScreenPos((area_name_.Min * scale) + offset);
			ImGui::Text(name_);
		}

		ImGuiNodesOutput(const char* name, ImGuiNodesConnectorType type)
		{
			type_ = type;
			state_ = ImGuiNodesConnectorStateFlag_Default;
			connections_ = 0;
			name_ = name;

			area_name_.Min = ImVec2(0.0f, 0.0f) - ImGui::CalcTextSize(name);
			area_name_.Max = ImVec2(0.0f, 0.0f);

			area_output_.Min.x = ImGuiNodesConnectorDotPadding + ImGuiNodesConnectorDotDiameter + ImGuiNodesConnectorDotPadding;
			area_output_.Min.y = ImGuiNodesConnectorDistance;
			area_output_.Min *= -area_name_.GetHeight();
			area_output_.Max = ImVec2(0.0f, 0.0f);

			ImVec2 offset = ImVec2(0.0f, 0.0f) - area_output_.GetCenter();

			area_name_.Translate(ImVec2(area_output_.Min.x, (area_output_.GetHeight() - area_name_.GetHeight()) * -0.5f));

			area_output_.Min.x -= area_name_.GetWidth();
			area_output_.Min.x -= ImGuiNodesConnectorDotPadding * area_name_.GetHeight();

			area_output_.Translate(offset);
			area_name_.Translate(offset);
		}
	};

	struct ImGuiNodesNode
	{
		ImRect area_node_;
		ImRect area_name_;
		float title_height_;
		float body_height_;
		ImGuiNodesNodeState state_;
		ImGuiNodesNodeType type_;
		const char* name_;
		ImColor color_;
		ImVector<ImGuiNodesInput> inputs_;
		ImVector<ImGuiNodesOutput> outputs_;

		inline void TranslateNode(ImVec2 delta, bool selected_only = false)
		{
			if (selected_only && !(state_ & ImGuiNodesNodeStateFlag_Selected))
				return;

			area_node_.Translate(delta);
			area_name_.Translate(delta);

			for (int input_idx = 0; input_idx < inputs_.size(); ++input_idx)
				inputs_[input_idx].TranslateInput(delta);
		
			for (int output_idx = 0; output_idx < outputs_.size(); ++output_idx)
				outputs_[output_idx].TranslateOutput(delta);
		}

		inline void BuildNodeGeometry(ImVec2 inputs_size, ImVec2 outputs_size)
		{
			body_height_ = ImMax(inputs_size.y, outputs_size.y) + (ImGuiNodesVSeparation * area_name_.GetHeight());

			area_node_.Min = ImVec2(0.0f, 0.0f);
			area_node_.Max = ImVec2(0.0f, 0.0f);
			area_node_.Max.x += inputs_size.x + outputs_size.x;
			area_node_.Max.x += ImGuiNodesHSeparation * area_name_.GetHeight();
			area_node_.Max.y += title_height_ + body_height_;

			area_name_.Translate(ImVec2((area_node_.GetWidth() - area_name_.GetWidth()) * 0.5f, ((title_height_ - area_name_.GetHeight()) * 0.5f)));

			ImVec2 inputs = area_node_.GetTL();
			inputs.y += title_height_ + (ImGuiNodesVSeparation * area_name_.GetHeight() * 0.5f);
			for (int input_idx = 0; input_idx < inputs_.size(); ++input_idx)
			{
				inputs_[input_idx].TranslateInput(inputs - inputs_[input_idx].area_input_.GetTL());
				inputs.y += inputs_[input_idx].area_input_.GetHeight();
			}

			ImVec2 outputs = area_node_.GetTR();
			outputs.y += title_height_ + (ImGuiNodesVSeparation * area_name_.GetHeight() * 0.5f);
			for (int output_idx = 0; output_idx < outputs_.size(); ++output_idx)
			{
				outputs_[output_idx].TranslateOutput(outputs - outputs_[output_idx].area_output_.GetTR());
				outputs.y += outputs_[output_idx].area_output_.GetHeight();
			}
		}

		inline void DrawNode(ImDrawList* draw_list, ImVec2 offset, float scale, ImGuiNodesState state) const
		{
			if (false == (state_ & ImGuiNodesNodeStateFlag_Visible))
				return;

			ImRect node_rect = area_node_;
			node_rect.Min *= scale;
			node_rect.Max *= scale;
			node_rect.Translate(offset);

			float rounding = title_height_ * scale * 0.3f;

			ImColor head_color = color_, body_color = color_;
			head_color.Value.x *= 0.5;
			head_color.Value.y *= 0.5;
			head_color.Value.z *= 0.5;

			head_color.Value.w = 1.00f;
			body_color.Value.w = 0.75f;		

			const ImVec2 outline(4.0f * scale, 4.0f * scale);

			const ImDrawFlags rounding_corners_flags = ImDrawCornerFlags_All;

			if (state_ & ImGuiNodesNodeStateFlag_Disabled)
			{
				body_color.Value.w = 0.25f;

				if (state_ & ImGuiNodesNodeStateFlag_Collapsed)
					head_color.Value.w = 0.25f;
			}

			if (state_ & ImGuiNodesNodeStateFlag_Processing)
				draw_list->AddRectFilled(node_rect.Min - outline, node_rect.Max + outline, body_color, rounding, rounding_corners_flags);
			else
				draw_list->AddRectFilled(node_rect.Min, node_rect.Max, body_color, rounding, rounding_corners_flags);

			const ImVec2 head = node_rect.GetTR() + ImVec2(0.0f, title_height_ * scale);

			if (false == (state_ & ImGuiNodesNodeStateFlag_Collapsed))
				draw_list->AddLine(ImVec2(node_rect.Min.x, head.y), ImVec2(head.x - 1.0f, head.y), ImColor(0.0f, 0.0f, 0.0f, 0.5f), 2.0f);
		
			const ImDrawFlags head_corners_flags = state_ & ImGuiNodesNodeStateFlag_Collapsed ? rounding_corners_flags : ImDrawCornerFlags_Top;
			draw_list->AddRectFilled(node_rect.Min, head, head_color, rounding, head_corners_flags);	

			////////////////////////////////////////////////////////////////////////////////

			if (state_ & ImGuiNodesNodeStateFlag_Disabled)
			{
				IM_ASSERT(false == node_rect.IsInverted());

				const float separation = 15.0f * scale;

				for (float line = separation; true; line += separation)
				{
					ImVec2 start = node_rect.Min + ImVec2(0.0f, line);
					ImVec2 stop = node_rect.Min + ImVec2(line, 0.0f);

					if (start.y > node_rect.Max.y)
						start = ImVec2(start.x + (start.y - node_rect.Max.y), node_rect.Max.y);

					if (stop.x > node_rect.Max.x)
						stop = ImVec2(node_rect.Max.x, stop.y + (stop.x - node_rect.Max.x));

					if (start.x > node_rect.Max.x)
						break;

					if (stop.y > node_rect.Max.y)
						break;

					draw_list->AddLine(start, stop, body_color, 3.0f * scale);
				}
			}

			////////////////////////////////////////////////////////////////////////////////

			if (false == (state_ & ImGuiNodesNodeStateFlag_Collapsed))
			{
				for (int input_idx = 0; input_idx < inputs_.size(); ++input_idx)
					inputs_[input_idx].DrawInput(draw_list, offset, scale, state);

				for (int output_idx = 0; output_idx < outputs_.size(); ++output_idx)
					outputs_[output_idx].DrawOutput(draw_list, offset, scale, state);
			}

			////////////////////////////////////////////////////////////////////////////////

			ImGui::SetCursorScreenPos(((area_name_.Min + ImVec2(2, 2)) * scale) + offset);
			ImGui::PushStyleColor(ImGuiCol_Text, IM_COL32(0, 0, 0, 255));
			ImGui::Text(name_);
			ImGui::PopStyleColor();

			ImGui::SetCursorScreenPos((area_name_.Min * scale) + offset);
			ImGui::Text(name_);

			if (state_ & (ImGuiNodesNodeStateFlag_Marked | ImGuiNodesNodeStateFlag_Selected))
				draw_list->AddRectFilled(node_rect.Min, node_rect.Max, ImColor(1.0f, 1.0f, 1.0f, 0.25f), rounding, rounding_corners_flags);

			if (state_ & ImGuiNodesNodeStateFlag_Processing)
			{
				ImColor processing_color = color_;
				processing_color.Value.x *= 1.5;
				processing_color.Value.y *= 1.5;
				processing_color.Value.z *= 1.5;
				processing_color.Value.w = 1.0f;

				draw_list->AddRect(node_rect.Min - outline, node_rect.Max + outline, processing_color, rounding, rounding_corners_flags, 2.0f * scale);		
			}
			else
			{
				draw_list->AddRect
				(
					node_rect.Min - outline * 0.5f,
					node_rect.Max + outline * 0.5f,
					ImColor(0.0f, 0.0f, 0.0f, 0.5f),
					rounding,
					rounding_corners_flags,
					3.0f * scale
				);		
			}
		}

		ImGuiNodesNode(const char* name, ImGuiNodesNodeType type, ImColor color)
		{
			name_ = name;
			type_ = type;
			state_ = ImGuiNodesNodeStateFlag_Default;
			color_ = color;

			area_name_.Min = ImVec2(0.0f, 0.0f);
			area_name_.Max = ImGui::CalcTextSize(name);
			title_height_ = ImGuiNodesTitleHight * area_name_.GetHeight();
		}
	};

	////////////////////////////////////////////////////////////////////////////////

	//ImGuiNodesConnectionDesc size round up to 32 bytes to be cache boundaries friendly
	constexpr int ImGuiNodesNamesMaxLen = 32 - sizeof(ImGuiNodesConnectorType);

	struct ImGuiNodesConnectionDesc
	{
		char name_[ImGuiNodesNamesMaxLen];
		ImGuiNodesConnectorType type_;
	};

	//TODO: ImVector me
	struct ImGuiNodesNodeDesc
	{
		char name_[ImGuiNodesNamesMaxLen];
		ImGuiNodesNodeType type_;
		ImColor color_;
		ImVector<ImGuiNodesConnectionDesc> inputs_;
		ImVector<ImGuiNodesConnectionDesc> outputs_;
	};

	////////////////////////////////////////////////////////////////////////////////

	struct ImGuiNodes
	{
	private:
		ImVec2 mouse_;
		ImVec2 pos_;
		ImVec2 size_;
		ImVec2 scroll_;
		ImVec4 connection_;
		float scale_;

		////////////////////////////////////////////////////////////////////////////////

		ImGuiNodesState state_;

		ImRect area_;
		ImGuiNodesNode* element_node_ = NULL;
		ImGuiNodesInput* element_input_ = NULL;
		ImGuiNodesOutput* element_output_ = NULL;
		ImGuiNodesNode* processing_node_ = NULL;

		////////////////////////////////////////////////////////////////////////////////

		ImVector<ImGuiNodesNode*> nodes_;
		ImVector<ImGuiNodesNodeDesc> nodes_desc_;

		////////////////////////////////////////////////////////////////////////////////
	
	private:
		void UpdateCanvasGeometry(ImDrawList* draw_list);
		ImGuiNodesNode* UpdateNodesFromCanvas();
		ImGuiNodesNode* CreateNodeFromDesc(ImGuiNodesNodeDesc* desc, ImVec2 pos);

		inline void DrawConnection(ImVec2 p1, ImVec2 p4, ImColor color)
		{		
			ImDrawList* draw_list = ImGui::GetWindowDrawList();

			float line = 25.0f;

			ImVec2 p2 = p1;
			ImVec2 p3 = p4;

			p2 += (ImVec2(-line, 0.0f) * scale_);
			p3 += (ImVec2(+line, 0.0f) * scale_);

			draw_list->AddBezierCurve(p1, p2, p3, p4, color, 1.5f * scale_);
		}

		inline bool ConnectionMatrix(ImGuiNodesNode* input_node, ImGuiNodesNode* output_node, ImGuiNodesInput* input, ImGuiNodesOutput* output)
		{
			if (input->target_ && input->target_ == output_node)
				return false;
			
			if (input->type_ == output->type_)
				return true;

			if (input->type_ == ImGuiNodesConnectorType_Generic)
				return true;

			if (output->type_ == ImGuiNodesConnectorType_Generic)
				return true;

			return false;
		}

		inline bool SortSelectedNodesOrder();
	public:
		void Update();
		void ProcessNodes();
		void ProcessContextMenu();

		ImGuiNodes()
		{
			scale_ = 1.0f;
			state_ = ImGuiNodesState_Default;
			element_node_ = NULL;
			element_input_ = NULL;
			element_output_ = NULL;

			////////////////////////////////////////////////////////////////////////////////

			{
				ImGuiNodesNodeDesc desc("Test", ImGuiNodesNodeType_Generic, ImColor(0.2, 0.3, 0.6, 0.0f));
				nodes_desc_.push_back(desc);
			
				desc.inputs_.push_back({ "Float", ImGuiNodesConnectorType_Float });
				desc.inputs_.push_back({ "Int", ImGuiNodesConnectorType_Int });
				desc.inputs_.push_back({ "TextStream", ImGuiNodesConnectorType_Text });
				
				desc.outputs_.push_back({ "Float", ImGuiNodesConnectorType_Float });
				
				auto& back = nodes_desc_.back();
				back.inputs_ = desc.inputs_;
				back.outputs_ = desc.outputs_;
			}

			{
				ImGuiNodesNodeDesc desc("InputBox", ImGuiNodesNodeType_Generic, ImColor(0.3, 0.5, 0.5, 0.0f));
				nodes_desc_.push_back(desc);
			
				desc.inputs_.push_back({ "Float1", ImGuiNodesConnectorType_Float });
				desc.inputs_.push_back({ "Float2", ImGuiNodesConnectorType_Float });
				desc.inputs_.push_back({ "Int1", ImGuiNodesConnectorType_Int });
				desc.inputs_.push_back({ "Int2", ImGuiNodesConnectorType_Int });
				desc.inputs_.push_back({ "", ImGuiNodesConnectorType_None });
				desc.inputs_.push_back({ "GenericSink", ImGuiNodesConnectorType_Generic });
				desc.inputs_.push_back({ "", ImGuiNodesConnectorType_None });
				desc.inputs_.push_back({ "Vector", ImGuiNodesConnectorType_Vector });
				desc.inputs_.push_back({ "Image", ImGuiNodesConnectorType_Image });
				desc.inputs_.push_back({ "Text", ImGuiNodesConnectorType_Text });
			
				desc.outputs_.push_back({ "TextStream", ImGuiNodesConnectorType_Text });
				desc.outputs_.push_back({ "", ImGuiNodesConnectorType_None });
				desc.outputs_.push_back({ "Float", ImGuiNodesConnectorType_Float });
				desc.outputs_.push_back({ "", ImGuiNodesConnectorType_None });
				desc.outputs_.push_back({ "Int", ImGuiNodesConnectorType_Int });
			
				auto& back = nodes_desc_.back();
				back.inputs_.swap(desc.inputs_);
				back.outputs_.swap(desc.outputs_);
			}
			
			{
				ImGuiNodesNodeDesc desc("OutputBox", ImGuiNodesNodeType_Generic, ImColor(0.4, 0.3, 0.5, 0.0f));
				nodes_desc_.push_back(desc);
			
				desc.inputs_.push_back({ "GenericSink1", ImGuiNodesConnectorType_Generic });
				desc.inputs_.push_back({ "GenericSink2", ImGuiNodesConnectorType_Generic });
				desc.inputs_.push_back({ "", ImGuiNodesConnectorType_None });
				desc.inputs_.push_back({ "Float", ImGuiNodesConnectorType_Float });
				desc.inputs_.push_back({ "Int", ImGuiNodesConnectorType_Int });
				desc.inputs_.push_back({ "Text", ImGuiNodesConnectorType_Text });
			
				desc.outputs_.push_back({ "Vector", ImGuiNodesConnectorType_Vector });
				desc.outputs_.push_back({ "Image", ImGuiNodesConnectorType_Image });
				desc.outputs_.push_back({ "Text", ImGuiNodesConnectorType_Text });
				desc.outputs_.push_back({ "", ImGuiNodesConnectorType_None });
				desc.outputs_.push_back({ "Float", ImGuiNodesConnectorType_Float });
				desc.outputs_.push_back({ "Int", ImGuiNodesConnectorType_Int });
				desc.outputs_.push_back({ "", ImGuiNodesConnectorType_None });
				desc.outputs_.push_back({ "", ImGuiNodesConnectorType_None });
				desc.outputs_.push_back({ "", ImGuiNodesConnectorType_None });
				desc.outputs_.push_back({ "Generic", ImGuiNodesConnectorType_Generic });
			
				auto& back = nodes_desc_.back();
				back.inputs_.swap(desc.inputs_);
				back.outputs_.swap(desc.outputs_);
			}

			////////////////////////////////////////////////////////////////////////////////

			return;
		}

		~ImGuiNodes()
		{
			for (int desc_idx = 0; desc_idx < nodes_desc_.size(); ++desc_idx)
			{
				ImGuiNodesNodeDesc& node = nodes_desc_[desc_idx];

				node.inputs_.~ImVector();
				node.outputs_.~ImVector();
			}
			
			for (int node_idx = 0; node_idx < nodes_.size(); ++node_idx)
				delete nodes_[node_idx];
		}
	};

	////////////////////////////////////////////////////////////////////////////////
}

Node collapsing and node deleting are implemented
Many asserts are added
There is also a nicer grid with marks every 5 units and bold canvas origin

Bug-fix: nodes.cpp on line339 to: nodes_[node_idx++] = nodes_unselected[unselected_idx];

A heads-up for all comers with ImGui v1.90.1 or newer =)

On nodes.h...

• L313, L334: ImDrawCornerFlags is no longer there
  • likely fix: I guess all ImDrawCornerFlags_Foo change to ImDrawFlags_RoundCornersFoo
• L478: ImDrawList.AddBezierCurve is no longer there
  • fix: was renamed to AddBezierCubic in 2020 =)
• L515, L530, L556: looks like ImGuiNodesNodeDesc had breaking changes in constructor signature(s)
  • likely fix: change from desc(myName, myTy, myCol) to desc{myName, myTy, myCol}

On nodes.cpp...

• L23, L705: current ImGui::IsKeyPressed has no overload matching the call
  • likely fix: ImGui::IsKeyPressed(ImGuiKey_Foo, false)
• probably due to my local setup with clangd in VSCode, but getting No member named 'fmodf' in namespace 'std'; did you mean simply 'fmodf'? for std::fmodf
  • easy fix tho at my end, remove std:: prefix

@metaleap
Indeed, this code snippet utilizes some 'older' ImGui API, let me follow your list one by one (in reversed order):

• std::fmodf == fmodf [OK]
• ImGui::IsKeyPressed(io.KeyMap[foo] --> ImGui::IsKeyPressed(foo)
• ImGuiNodesNodeDesc ctor as you proposed
• ImDrawList.AddBezierCurve: here, I am no longer using Bezier curves due to computational overhead (eg. hover detection) - they are just multiple lines. In my final assessment I am using strict lines, which I am recommended to use for nodes-editor low latency
• as you've noticed: ImDrawCornerFlags_Foo --> ImDrawFlags_RoundCornersFoo

Please note the purpose of this snippet: ocornut/imgui#306 (comment)
There is much to be done beyond its state-machine (not even touched in this snippet), such as: finding self-cycles, (perhaps) inheritance, serialization, "execution" order, undo/redo, etc.
Here is a glimpse of what I am doing based on that (with history): https://youtu.be/qkikedz6Wyo

Here is a glimpse of what I am doing based on that (with history): https://youtu.be/qkikedz6Wyo

Lookin' real neat! Have actually briefly deferred my need for nodes-editing but thanks for the pointers, will see how it goes when the time comes.

Is there anything to be aware of in regards to permission of use / licensing? I'm working on a single binary / static build project and I'm currently considering forking this and as a base for my own node editor, I don't have any commercial intentions, and will probably end up releasing the project on GitHub eventually

@paccerdk it's free/public domain, enjoy ☺️
ocornut/imgui#306 (comment)

That's amazing - Thank you for this!

@paccerdk: you are welcome, here is an interface legend-list: ocornut/imgui#306 (comment)
I encourage you to share your attack on #306 whenever it's ready.

2024-01-12.20-16-00-353.mp4

I kind of did what you wrote

if (ImGui::Begin("Node Editor")) {
	this->imguiNodes.Update();
	this->imguiNodes.ProcessNodes();
	this->imguiNodes.ProcessContextMenu();
}
ImGui::End();

This helped, but I'm not sure it's a good solution.

ImGui::GetIO().ConfigWindowsMoveFromTitleBarOnly = true;

@GeTechG: yes, that's the way