node_graph_example
// NB: You can use math functions/operators on ImVec2 if you #define IMGUI_DEFINE_MATH_OPERATORS and #include "imgui_internal.h"
// Here we only declare simple +/- operators so others don't leak into the demo code.
static inline ImVec2 operator+(const ImVec2& lhs, const ImVec2& rhs) { return ImVec2(lhs.x+rhs.x, lhs.y+rhs.y); }
static inline ImVec2 operator-(const ImVec2& lhs, const ImVec2& rhs) { return ImVec2(lhs.x-rhs.x, lhs.y-rhs.y); }
// Really dumb data structure provided for the example.
// Note that we storing links are INDICES (not ID) to make example code shorter, obviously a bad idea for any general purpose code.
static void ShowExampleAppCustomNodeGraph(bool* opened)
{
ImGui::SetNextWindowSize(ImVec2(700,600), ImGuiSetCond_FirstUseEver);
if (!ImGui::Begin("Example: Custom Node Graph", opened))
{
ImGui::End();
return;
}
struct Node
{
int ID;
char Name[32];
ImVec2 Pos, Size;
float Value;
int InputsCount, OutputsCount;
Node(int id, const char* name, const ImVec2& pos, float value, int inputs_count, int outputs_count) { ID = id; strncpy(Name, name, 31); Name[31] = 0; Pos = pos; Value = value; InputsCount = inputs_count; OutputsCount = outputs_count; }
ImVec2 GetInputSlotPos(int slot_no) const { return ImVec2(Pos.x, Pos.y + Size.y * ((float)slot_no+1) / ((float)InputsCount+1)); }
ImVec2 GetOutputSlotPos(int slot_no) const { return ImVec2(Pos.x + Size.x, Pos.y + Size.y * ((float)slot_no+1) / ((float)OutputsCount+1)); }
};
struct NodeLink
{
int InputIdx, InputSlot, OutputIdx, OutputSlot;
NodeLink(int input_idx, int input_slot, int output_idx, int output_slot) { InputIdx = input_idx; InputSlot = input_slot; OutputIdx = output_idx; OutputSlot = output_slot; }
};
static ImVector<Node> nodes;
static ImVector<NodeLink> links;
static bool inited = false;
static ImVec2 scrolling = ImVec2(0.0f, 0.0f);
static int node_selected = -1;
if (!inited)
{
nodes.push_back(Node(0, "MainTex", ImVec2(40,50), 0.5f, 1, 1));
nodes.push_back(Node(1, "BumpMap", ImVec2(40,150), 0.42f, 1, 1));
nodes.push_back(Node(2, "Combine", ImVec2(270,80), 1.0f, 2, 2));
links.push_back(NodeLink(0, 0, 2, 0));
links.push_back(NodeLink(1, 0, 2, 1));
inited = true;
}
// Draw a list
bool open_context_menu = false;
int node_hovered_in_list = -1;
int node_hovered_in_scene = -1;
ImGui::BeginChild("node_list", ImVec2(100,0));
ImGui::Text("Nodes");
ImGui::Separator();
for (int node_idx = 0; node_idx < nodes.Size; node_idx++)
{
Node* node = &nodes[node_idx];
ImGui::PushID(node->ID);
if (ImGui::Selectable(node->Name, node->ID == node_selected))
node_selected = node->ID;
if (ImGui::IsItemHovered())
{
node_hovered_in_list = node->ID;
open_context_menu |= ImGui::IsMouseClicked(1);
}
ImGui::PopID();
}
ImGui::EndChild();
ImGui::SameLine();
ImGui::BeginGroup();
const float NODE_SLOT_RADIUS = 4.0f;
const ImVec2 NODE_WINDOW_PADDING(8.0f, 8.0f);
ImGui::Text("Hold middle mouse button to scroll (%.2f,%.2f)", scrolling.x, scrolling.y);
ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(1,1));
ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0,0));
ImGui::PushStyleColor(ImGuiCol_ChildWindowBg, ImColor(40,40,40,200));
ImGui::BeginChild("scrolling_region", ImVec2(0,0), true, ImGuiWindowFlags_NoScrollbar|ImGuiWindowFlags_NoMove);
ImGui::PushItemWidth(120.0f);
ImDrawList* draw_list = ImGui::GetWindowDrawList();
draw_list->ChannelsSplit(2);
ImVec2 offset = ImGui::GetCursorScreenPos() - scrolling;
// Display links
draw_list->ChannelsSetCurrent(0); // Background
for (int link_idx = 0; link_idx < links.Size; link_idx++)
{
NodeLink* link = &links[link_idx];
Node* node_inp = &nodes[link->InputIdx];
Node* node_out = &nodes[link->OutputIdx];
#if 1
// Hermite spline
// TODO: move to Path API
ImVec2 p1 = offset+node_inp->GetOutputSlotPos(link->InputSlot);
ImVec2 t1 = ImVec2(+80.0f, 0.0f);
ImVec2 p2 = offset+node_out->GetInputSlotPos(link->OutputSlot);
ImVec2 t2 = ImVec2(+80.0f, 0.0f);
const int STEPS = 12;
for (int step = 0; step <= STEPS; step++)
{
float t = (float)step / (float)STEPS;
float h1 = +2*t*t*t - 3*t*t + 1.0f;
float h2 = -2*t*t*t + 3*t*t;
float h3 = t*t*t - 2*t*t + t;
float h4 = t*t*t - t*t;
draw_list->PathLineTo(ImVec2(h1*p1.x + h2*p2.x + h3*t1.x + h4*t2.x, h1*p1.y + h2*p2.y + h3*t1.y + h4*t2.y));
}
draw_list->PathStroke(ImColor(200,200,100), false, 3.0f);
#else
draw_list->AddLine(offset+node_inp->GetOutputSlotPos(link->InputSlot), offset+node_out->GetInputSlotPos(link->OutputSlot), ImColor(200,200,100), 3.0f);
#endif
}
// Display nodes
for (int node_idx = 0; node_idx < nodes.Size; node_idx++)
{
Node* node = &nodes[node_idx];
ImGui::PushID(node->ID);
ImVec2 node_rect_min = offset + node->Pos;
// Display node contents first
draw_list->ChannelsSetCurrent(1); // Foreground
bool 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, 0.0f, 1.0f, "Alpha %.2f");
float dummy_color[3] = { node->Pos.x / ImGui::GetWindowWidth(), node->Pos.y / ImGui::GetWindowHeight(), fmodf((float)node->ID * 0.5f, 1.0f) };
ImGui::ColorEdit3("##color", &dummy_color[0]);
ImGui::EndGroup();
node->Size = ImGui::GetItemRectSize() + NODE_WINDOW_PADDING + NODE_WINDOW_PADDING;
ImVec2 node_rect_max = node_rect_min + node->Size;
bool node_widgets_active = (!old_any_active && ImGui::IsAnyItemActive());
// Display node box
draw_list->ChannelsSetCurrent(0); // Background
ImGui::SetCursorScreenPos(node_rect_min);
ImGui::InvisibleButton("node", node->Size);
if (ImGui::IsItemHovered())
{
node_hovered_in_scene = node->ID;
open_context_menu |= ImGui::IsMouseClicked(1);
}
bool node_moving_active = ImGui::IsItemActive();
if (node_widgets_active || node_moving_active)
node_selected = node->ID;
if (node_moving_active && ImGui::IsMouseDragging(0))
{
node->Pos.x += ImGui::GetIO().MouseDelta.x;
node->Pos.y += ImGui::GetIO().MouseDelta.y;
}
draw_list->AddRectFilled(node_rect_min, node_rect_max, (node_hovered_in_list == node->ID || node_hovered_in_scene == node->ID || (node_hovered_in_list == -1 && node_selected == node->ID)) ? ImColor(75,75,75) : ImColor(60,60,60), 4.0f);
draw_list->AddRect(node_rect_min, node_rect_max, ImColor(100,100,100), 4.0f);
for (int slot_idx = 0; slot_idx < node->InputsCount; slot_idx++)
{
ImVec2 pos = node->GetInputSlotPos(slot_idx);
draw_list->AddCircleFilled(offset + pos, NODE_SLOT_RADIUS, ImColor(150,150,150,150));
}
for (int slot_idx = 0; slot_idx < node->OutputsCount; slot_idx++)
{
ImVec2 pos = node->GetOutputSlotPos(slot_idx);
draw_list->AddCircleFilled(offset+pos, NODE_SLOT_RADIUS, ImColor(150,150,150,150));
}
ImGui::PopID();
}
draw_list->ChannelsMerge();
// Open context menu
if (!ImGui::IsAnyItemHovered() && ImGui::IsMouseHoveringWindow() && ImGui::IsMouseClicked(1))
{
node_selected = node_hovered_in_list = node_hovered_in_scene = -1;
open_context_menu = true;
}
if (open_context_menu)
{
ImGui::OpenPopup("context_menu");
if (node_hovered_in_list != -1)
node_selected = node_hovered_in_list;
if (node_hovered_in_scene != -1)
node_selected = node_hovered_in_scene;
}
// Draw context menu
ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(8,8));
if (ImGui::BeginPopup("context_menu"))
{
Node* node = node_selected != -1 ? &nodes[node_selected] : NULL;
ImVec2 scene_pos = ImGui::GetMousePosOnOpeningCurrentPopup() - offset;
if (node)
{
ImGui::Text("Node '%s'", node->Name);
ImGui::Separator();
if (ImGui::MenuItem("Rename..", NULL, false, false)) {}
if (ImGui::MenuItem("Delete", NULL, false, false)) {}
if (ImGui::MenuItem("Copy", NULL, false, false)) {}
}
else
{
if (ImGui::MenuItem("Add")) { nodes.push_back(Node(nodes.Size, "New node", scene_pos, 0.5f, 2, 2)); }
if (ImGui::MenuItem("Paste", NULL, false, false)) {}
}
ImGui::EndPopup();
}
ImGui::PopStyleVar();
// Scrolling
if (ImGui::IsWindowHovered() && !ImGui::IsAnyItemActive() && ImGui::IsMouseDragging(2, 0.0f))
{
scrolling.x -= ImGui::GetIO().MouseDelta.x;
scrolling.y -= ImGui::GetIO().MouseDelta.y;
}
ImGui::PopItemWidth();
ImGui::EndChild();
ImGui::PopStyleColor();
ImGui::PopStyleVar(2);
ImGui::EndGroup();
ImGui::End();
}