In Progress example for NodeGraph

- using https://gist.github.com/ocornut/7e9b3ec566a333d725d4

demo/CustomNodeGraph.pas

@@ -0,0 +1,350 @@
+{
+  FreePascal / Delphi bindings for ImGui
+
+  Copyright (C) 2023 Coldzer0 <Coldzer0 [at] protonmail.ch>
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the MIT License.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  MIT License for more details.
+}
+
+unit CustomNodeGraph;
+
+{$IfDef FPC}
+  {$mode Delphi}{$H+}
+  {$ModeSwitch advancedrecords}
+{$EndIf}
+
+{$J+} // Allow const var change
+
+Interface
+
+Uses
+  Generics.Collections,
+  SysUtils,
+  PasImGui,
+  PasImGui.Apis,
+  PasImGui.Types,
+  PasImGui.Enums;
+
+Type
+  { TNode }
+
+  TNode = Record
+    ID: Integer;
+    Name: Array [0..31] Of AnsiChar;
+    Pos, Size: ImVec2;
+    Value: Single;
+    Color: ImVec4;
+    InputsCount, OutputsCount: Integer;
+    function GetInputSlotPos(slotNo: Integer): ImVec2;
+    function GetOutputSlotPos(slotNo: Integer): ImVec2;
+    constructor Create(id_: Integer;
+      const Name_: PAnsiChar; pos_: ImVec2; Value_: Single; color_: ImVec4; inputsCount_, outputsCount_: Integer);
+  End;
+
+  { TNodeLink }
+
+  TNodeLink = record
+    InputIdx, InputSlot, OutputIdx, OutputSlot: Integer;
+    constructor Create(inputIdx_, inputSlot_, outputIdx_, outputSlot_: Integer);
+  end;
+
+  Procedure ShowExampleAppCustomNodeGraph(opened: PBoolean);
+
+Implementation
+  uses
+    Math;
+
+var
+  nodes : TList<TNode>;
+  links : TList<TNodeLink>;
+  scrolling  : ImVec2;
+
+Procedure ShowExampleAppCustomNodeGraph(opened: PBoolean);
+var
+  io : PImGuiIO;
+  node, node_inp , node_out: TNode;
+  link: TNodeLink;
+  node_idx, slot_idx, link_idx: Integer;
+  offset, win_pos, canvas_sz, p1, p2, node_rect_min, node_rect_max,
+    scene_pos: ImVec2;
+  draw_list: PImDrawList;
+  GRID_COLOR, node_bg_color: ImU32;
+  GRID_SZ, x, y: Single;
+  old_any_active, node_widgets_active, node_moving_active: Boolean;
+const
+  open_context_menu : Boolean = False;
+  node_hovered_in_list : Integer = -1;
+  node_hovered_in_scene : Integer = -1;
+
+  inited : Boolean = False;
+  show_grid : Boolean = False;
+  node_selected : Integer = -1;
+
+  NODE_SLOT_RADIUS : Single = 4.0;
+  NODE_WINDOW_PADDING : ImVec2 = (x:8.0; y:8.0);
+Begin
+  scrolling := ImVec2.New(0.0, 0.0);
+  ImGui.SetNextWindowSize(ImVec2.New(700, 600), ImGuiCond_FirstUseEver);
+  ImGui.SetNextWindowPosCenter(ImGuiCond_FirstUseEver);
+  If Not ImGui.Begin_('Greeting') Then
+  Begin
+    ImGui.End_;  // Early out if the window is collapsed, as an optimization.
+    exit;
+  End;
+
+  io := ImGui.GetIO();
+
+  if not inited then
+  begin
+    nodes := TList<TNode>.Create();
+    links := TList<TNodeLink>.Create();
+
+
+    nodes.Add(TNode.Create(0, 'MainTex', ImVec2.New(40, 50), 0.5, ImVec4.New(255, 100, 100), 1, 1));
+    nodes.Add(TNode.Create(1, 'BumpMap', ImVec2.New(40, 150), 0.42, ImVec4.New(200, 100, 200), 1, 1));
+    nodes.Add(TNode.Create(2, 'Combine', ImVec2.New(270, 80), 1.0, ImVec4.New(0, 200, 100), 2, 2));
+    links.Add(TNodeLink.Create(0, 0, 2, 0));
+    links.Add(TNodeLink.Create(1, 0, 2, 1));
+
+    inited := True;
+  end;
+  // Draw a list of nodes on the left side
+  ImGui.BeginChild('node_list', ImVec2.New(100, 0));
+  ImGui.Text('Nodes');
+  ImGui.Separator();
+
+  for node_idx := 0 to Pred(nodes.Count) do
+  begin
+    node := &nodes[node_idx];
+    ImGui.PushIdInt(node.ID);
+    if ImGui.Selectable(String(node.Name), node.ID = node_selected) then
+      node_selected := node.ID;
+
+    if ImGui.IsItemHovered() then
+    begin
+      node_hovered_in_list := node.ID;
+      open_context_menu := open_context_menu or ImGui.IsMouseClicked(1);
+    end;
+    ImGui.PopID();
+  end;
+  ImGui.EndChild();
+  ImGui.SameLine();
+
+  ImGui.BeginGroup();
+  // Create our child canvas
+  ImGui.Text('Hold middle mouse button to scroll (%.2f,%.2f)', [scrolling.x, scrolling.y]);
+  ImGui.SameLine(ImGui.GetWindowWidth() - 100);
+  ImGui.Checkbox('Show grid', @show_grid);
+  ImGui.PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2.New(1, 1));
+  ImGui.PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2.New(0, 0));
+  ImGui.PushStyleColor(ImGuiCol_ChildBg, IM_COL32(60, 60, 70, 200));
+  ImGui.BeginChild('scrolling_region', ImVec2.New(0, 0), ImGuiChildFlags_Border, ImGuiWindowFlags_NoScrollbar or ImGuiWindowFlags_NoMove);
+  ImGui.PopStyleVar(); // WindowPadding
+  ImGui.PushItemWidth(120.0);
+
+  offset := ImGui.GetCursorScreenPos() + scrolling;
+  draw_list := ImGui.GetWindowDrawList();
+
+  if show_grid then
+  begin
+    GRID_COLOR := IM_COL32(200, 200, 200, 40);
+    GRID_SZ := 64.0;
+    win_pos := ImGui.GetCursorScreenPos();
+    canvas_sz := ImGui.GetWindowSize();
+
+    x := fmod(scrolling.x, GRID_SZ);
+    while x < canvas_sz.x do
+    begin
+      draw_list^.AddLine(ImVec2.New(x, 0.0) + win_pos, ImVec2.New(x, canvas_sz.y) + win_pos, GRID_COLOR);
+      x := fmod(scrolling.x, GRID_SZ);
+    end;
+
+    y := fmod(scrolling.y, GRID_SZ);
+    while y < canvas_sz.y do
+    begin
+      draw_list^.AddLine(ImVec2.New(0.0, y) + win_pos, ImVec2.New(canvas_sz.x, y) + win_pos, GRID_COLOR);
+      y := fmod(scrolling.y, GRID_SZ);
+    end;
+  end;
+
+  // Display links
+  draw_list^.ChannelsSplit(2);
+  draw_list^.ChannelsSetCurrent(0); // Background
+
+  for link_idx := 0 to Pred(links.Count) do
+  begin
+    link := &links[link_idx];
+    node_inp := &nodes[link.InputIdx];
+    node_out := &nodes[link.OutputIdx];
+    p1 := offset + node_inp.GetOutputSlotPos(link.InputSlot);
+    p2 := offset + node_out.GetInputSlotPos(link.OutputSlot);
+    draw_list^.AddBezierCubic(p1, p1 + ImVec2.New(+50, 0), p2 + ImVec2.New(-50, 0), p2, IM_COL32(200, 200, 100, 255), 3.0);
+  end;
+
+  // Display nodes
+  for node_idx := 0 to Pred(nodes.Count) do
+  begin
+    node := &nodes[node_idx];
+
+    ImGui.PushIdInt(node.ID);
+    node_rect_min := offset + node.Pos;
+
+    // Display node contents first
+    draw_list^.ChannelsSetCurrent(1); // Foreground
+    old_any_active := ImGui.IsAnyItemActive();
+    ImGui.SetCursorScreenPos(node_rect_min + NODE_WINDOW_PADDING);
+    ImGui.BeginGroup(); // Lock horizontal position
+    ImGui.Text('%s', [node.Name]);
+    ImGui.SliderFloat('##value', @node.Value, 0.0, 1.0, 'Alpha %.2f');
+    ImGui.ColorEdit3('##color', @node.Color.x);
+    ImGui.EndGroup();
+
+    // Save the size of what we have emitted and whether any of the widgets are being used
+    node_widgets_active := (not old_any_active and ImGui.IsAnyItemActive());
+    node.Size := ImGui.GetItemRectSize() + NODE_WINDOW_PADDING + NODE_WINDOW_PADDING;
+    node_rect_max := node_rect_min + node.Size;
+
+    // Display node box
+    draw_list^.ChannelsSetCurrent(0); // Background
+    ImGui.SetCursorScreenPos(node_rect_min);
+    ImGui.InvisibleButton('node', node.Size);
+    if ImGui.IsItemHovered() then
+    begin
+      node_hovered_in_scene := node.ID;
+      open_context_menu := open_context_menu or ImGui.IsMouseClicked(1);
+    end;
+    node_moving_active := ImGui.IsItemActive();
+    if (node_widgets_active or node_moving_active) then
+        node_selected := node.ID;
+    if (node_moving_active and ImGui.IsMouseDragging(ImGuiMouseButton_Left)) then
+        node.Pos := node.Pos + io^.MouseDelta;
+
+    if ((node_hovered_in_list = node.ID) or (node_hovered_in_scene = node.ID) or ((node_hovered_in_list = -1) and (node_selected = node.ID))) then
+      node_bg_color := IM_COL32(75, 75, 75, 255)
+    else
+      node_bg_color := IM_COL32(60, 60, 60, 255);
+
+    draw_list^.AddRectFilled(node_rect_min, node_rect_max, node_bg_color, 4.0);
+    draw_list^.AddRect(node_rect_min, node_rect_max, IM_COL32(100, 100, 100, 255), 4.0);
+
+    for slot_idx := 0 to Pred(node.InputsCount) do
+      draw_list^.AddCircleFilled(offset + node.GetInputSlotPos(slot_idx), NODE_SLOT_RADIUS, IM_COL32(150, 150, 150, 150));
+    for slot_idx  := 0 to Pred(node.OutputsCount) do
+      draw_list^.AddCircleFilled(offset + node.GetOutputSlotPos(slot_idx), NODE_SLOT_RADIUS, IM_COL32(150, 150, 150, 150));
+
+    ImGui.PopID();
+  end;
+  draw_list^.ChannelsMerge();
+
+  // Open context menu
+  if ImGui.IsMouseReleased(ImGuiMouseButton_Right) then
+  begin
+    if ImGui.IsWindowHovered(ImGuiHoveredFlags_AllowWhenBlockedByPopup) or not ImGui.IsAnyItemHovered() then
+    begin
+      node_hovered_in_list := -1;
+      node_hovered_in_scene := -1;;
+      node_selected := -1;
+      open_context_menu := true;
+    end;
+  end;
+  if open_context_menu then
+  begin
+    ImGui.OpenPopup('context_menu');
+    if (node_hovered_in_list <> -1) then
+        node_selected := node_hovered_in_list;
+    if (node_hovered_in_scene <> -1) then
+        node_selected := node_hovered_in_scene;
+  end;
+  // Draw context menu
+  ImGui.PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2.New(8, 8));
+  if ImGui.BeginPopup('context_menu') then
+  begin
+    if node_selected <> -1 then
+      node := &nodes[node_selected]
+    else
+      node.ID := -1;
+
+    scene_pos := ImGui.GetMousePosOnOpeningCurrentPopup() - offset;
+
+    if node.ID <> -1 then
+    begin
+      ImGui.Text('Node "%s"', [node.Name]);
+      ImGui.Separator();
+      if ImGui.MenuItem('Rename..', nil, false, false) then begin end;
+      if ImGui.MenuItem('Delete', nil, false, false) then begin end;
+      if ImGui.MenuItem('Copy', nil, false, false) then begin end;
+    end
+    else
+    begin
+      if ImGui.MenuItem('Add') then
+        nodes.Add(Node.Create(nodes.Count, 'New node', scene_pos, 0.5, ImVec4.New(100, 100, 200), 2, 2));
+      if ImGui.MenuItem('Past', nil, false, false) then begin end;
+    end;
+    ImGui.EndPopup();
+  end;
+  ImGui.PopStyleVar();
+
+  // Scrolling
+  if (ImGui.IsWindowHovered() and not ImGui.IsAnyItemActive() and ImGui.IsMouseDragging(ImGuiMouseButton_Middle, 0.0)) then
+      scrolling := scrolling + io.MouseDelta;
+
+  ImGui.PopItemWidth();
+  ImGui.EndChild();
+  ImGui.PopStyleColor();
+  ImGui.PopStyleVar();
+  ImGui.EndGroup();
+
+  ImGui.End_();
+End;
+
+{ TNode }
+
+function TNode.GetInputSlotPos(slotNo: Integer): ImVec2;
+begin
+  Result.x := Pos.x;
+  Result.y := Pos.y + Size.y * (slotNo + 1) / (InputsCount + 1);
+end;
+
+function TNode.GetOutputSlotPos(slotNo: Integer): ImVec2;
+begin
+  Result.x := Pos.x + Size.x;
+  Result.y := Pos.y + Size.y * (slotNo + 1) / (OutputsCount + 1);
+end;
+
+constructor TNode.Create(id_: Integer;
+  const Name_: PAnsiChar; pos_: ImVec2; Value_: Single; color_: ImVec4; inputsCount_, outputsCount_: Integer);
+Begin
+  Self.ID := id_;
+  StrLCopy(Self.Name, name_, SizeOf(Self.Name) - 1);
+  Self.Pos := pos_;
+  Self.Value := value_;
+  Self.Color := color_;
+  Self.InputsCount := inputsCount_;
+  Self.OutputsCount := outputsCount_;
+End;
+
+{ TNodeLink }
+
+constructor TNodeLink.Create(inputIdx_, inputSlot_, outputIdx_, outputSlot_: Integer);
+begin
+  Self.InputIdx := inputIdx_;
+  Self.InputSlot := inputSlot_;
+  Self.OutputIdx := outputIdx_;
+  Self.OutputSlot := outputSlot_;
+end;
+
+initialization
+
+
+finalization
+  nodes.Free;
+  links.Free;
+
+End.
+