src/gui/node_editor.h

   1 #pragma once
   2
   3 #include <string>
   4 #include <vector>
   5
   6 #define IMGUI_DEFINE_MATH_OPERATORS
   7 #include <imgui.h>
   8 #include <imgui_internal.h>
   9
  10 #include "../geom.h"
  11
  12 class GuiNode {
  13 public:
  14     GuiNode(std::string name, Rect bbox, uint n_slots_in, uint n_slots_out)
  15         : name(name), bbox(bbox), n_slots_in(n_slots_in), n_slots_out(n_slots_out)
  16             {}
  17
  18     enum SlotDirection {
  19         IN,
  20         OUT,
  21     };
  22
  23     ImVec2 slot_location(SlotDirection direction, uint i) const {
  24         uint n_slots;
  25         switch (direction) {
  26         case IN:
  27             n_slots = n_slots_in; break;
  28         case OUT:
  29             n_slots = n_slots_out; break;
  30         }
  31
  32         auto x_stride = bbox.size.y/(n_slots+1);
  33
  34         ImVec2 base;
  35         switch(direction) {
  36         case IN:
  37             base = bbox.pos; break;
  38         case OUT:
  39             base = bbox.pos + ImVec2(bbox.size.x, 0); break;
  40         }
  41
  42         return base + ImVec2(0, (i + 1) *  x_stride);
  43     }
  44
  45     uint n_slots_in;
  46     uint n_slots_out;
  47
  48     std::string name;
  49     Rect bbox;
  50 };
  51
  52 class GuiEdge {
  53 public:
  54     GuiEdge(GuiNode *lhs, GuiNode *rhs, uint fromSlot, uint toSlot)
  55         : lhs(lhs), rhs(rhs), fromSlot(fromSlot), toSlot(toSlot) {}
  56
  57
  58     GuiNode *lhs;
  59     GuiNode *rhs;
  60     uint fromSlot;
  61     uint toSlot;
  62 };
  63
  64 class NodeEditor {
  65 public:
  66     NodeEditor() {
  67         nodeList.emplace_back("hi", Rect(10, 10, 60, 60), 3, 1);
  68         nodeList.emplace_back("hi2", Rect(80, 10, 60, 60), 1, 1);
  69
  70         edgeList.emplace_back(&nodeList[0], &nodeList[1], 0, 0);
  71     }
  72
  73     void draw_window(const char *title, bool *opened) {
  74         ImGui::SetNextWindowSize(ImVec2(700,600), ImGuiSetCond_FirstUseEver);
  75         if (ImGui::Begin(title, opened)) {
  76             // -- Create child canvas
  77             ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(1,1));
  78             ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0,0));
  79             ImGui::PushStyleColor(ImGuiCol_ChildWindowBg, ImColor(60,60,70,200));
  80             ImGui::BeginChild("nodes_region", ImVec2(0, 0), true, ImGuiWindowFlags_NoScrollbar|ImGuiWindowFlags_NoMove);
  81
  82             // -- Prepare to draw
  83             // Get the draw list for this canvas
  84             ImDrawList* draw_list = ImGui::GetWindowDrawList();
  85             draw_list->ChannelsSplit(2);
  86
  87             // this gets the offset to the upper-right corner of the child canvas.
  88             // Note: here, cursor means "draw cursor", not "mouse pointing cursor".
  89             ImVec2 canvas_pos = ImGui::GetCursorScreenPos();
  90             ImVec2 canvas_size = ImGui::GetWindowSize();
  91
  92             ImVec2 offset = canvas_pos - scrolling; // TODO: add scrolling
  93
  94             // -- Draw the grid
  95             draw_list->ChannelsSetCurrent(0);
  96             if (show_grid) {
  97                 ImVec2 local_offset = ImGui::GetCursorPos() - scrolling;
  98
  99                 float spacing = 32.0f; ImU32 color = IM_COL32(200, 200, 200, 40);
 100
 101                 for (float x = fmodf(local_offset.x, spacing); x < canvas_size.x; x += spacing)
 102                     draw_list->AddLine(ImVec2(x, 0.0f)+canvas_pos,
 103                                        ImVec2(x, canvas_size.y)+canvas_pos, color);
 104                 for (float y = fmodf(local_offset.y, spacing); y < canvas_size.y; y += spacing)
 105                     draw_list->AddLine(ImVec2(0.0f, y)+canvas_pos,
 106                                        ImVec2(canvas_size.x, y)+canvas_pos, color);
 107             }
 108
 109
 110             draw_list->ChannelsSetCurrent(0);
 111             for (const auto &edge : edgeList) {
 112                 auto head = offset + edge.lhs->slot_location(GuiNode::OUT, edge.fromSlot);
 113                 auto tail = offset + edge.rhs->slot_location(GuiNode::IN,  edge.fromSlot);
 114
 115                 draw_list->AddBezierCurve(head, head+ImVec2(50, 0),
 116                                           tail+ImVec2(-50, 0), tail,
 117                                           ImColor(200, 200, 200), 3.0f);
 118             }
 119
 120             Rect viewportRect = Rect(scrolling, canvas_size);
 121
 122             for (auto &node : nodeList) {
 123                 bool visible = viewportRect.intersects(node.bbox);
 124                 if (visible) {
 125                     // TODO: this is garbage
 126                     ImGui::PushID((void *)&node);
 127
 128                     // -- Draw the node boxes
 129                     draw_list->ChannelsSetCurrent(0); // Switch to the background layer
 130
 131                     // draw an invisible button in the background, for dragging/hovering
 132                     ImGui::SetCursorScreenPos(offset + node.bbox.pos);
 133                     ImGui::InvisibleButton("node", node.bbox.size);
 134
 135                     if (ImGui::IsItemActive() && ImGui::IsMouseDragging(0))
 136                         node.bbox.pos += ImGui::GetIO().MouseDelta;
 137
 138                     ImVec2 upper_left = offset + node.bbox.pos;
 139                     ImVec2 lower_right = upper_left + node.bbox.size;
 140
 141                     draw_list->AddRectFilled(upper_left, lower_right, ImColor(60, 60, 60), 4.0f);
 142                     draw_list->AddRect(upper_left, lower_right, ImColor(100, 100, 100), 4.0f);
 143
 144                     // -- Draw the connection dots
 145                     for (int i=0; i<node.n_slots_in; i++) {
 146                         auto position = node.slot_location(GuiNode::IN, i);
 147                         draw_list->AddCircleFilled(offset + position, 4.0f, ImColor(150, 150, 150, 150));
 148                     }
 149
 150                     for (int i=0; i<node.n_slots_out; i++) {
 151                         auto position = node.slot_location(GuiNode::OUT, i);
 152                         draw_list->AddCircleFilled(offset + position, 4.0f, ImColor(150, 150, 150, 150));
 153                     }
 154
 155                     ImGui::PopID();
 156                 }
 157             }
 158
 159             // -- merge channels back together
 160             draw_list->ChannelsMerge();
 161
 162             // -- scrolling!
 163             //  [ pointer over neditor ]    [ not interacting ctrls ]    [    middle mouse dragging    ]
 164             if (ImGui::IsWindowHovered() && !ImGui::IsAnyItemActive() && ImGui::IsMouseDragging(2, 0.0f))
 165                 scrolling = scrolling - ImGui::GetIO().MouseDelta;
 166
 167             // -- clean up
 168             ImGui::EndChild();       // end :nodes_region
 169             ImGui::PopStyleColor();  // pop ChildWindowBg
 170             ImGui::PopStyleVar(2);   // pop FramePadding, WindowPadding
 171         }
 172         ImGui::End();
 173     }
 174
 175 private:
 176     std::vector<GuiNode> nodeList;
 177     std::vector<GuiEdge> edgeList;
 178
 179     ImVec2 scrolling = ImVec2(0.0f, 0.0f);
 180     bool show_grid = true;
 181 };