Files
fn_registry/cpp/functions/gfx/dag_node_editor.cpp
T
egutierrez cd445c5833 feat(shaders_lab): pins straddle node edges (half outside, half inside)
draw_pin_circle takes a PinSide and centers the circle exactly on the
left or right edge of the node. The reserved Dummy is half-width
(PIN_RADIUS instead of PIN_DIAMETER) so the inside layout stays
compact, and ed::PinRect is set to the full circle so the protruding
half is still grabbable.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-25 01:59:01 +02:00

536 lines
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#include "gfx/dag_node_editor.h"
#include "gfx/dag_catalog.h"
#include "imgui.h"
#include "imgui_node_editor.h"
#include <algorithm>
#include <cstdio>
#include <functional>
#include <queue>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
namespace ed = ax::NodeEditor;
namespace fn::gfx {
static constexpr int MAX_NODES = 16;
static ed::EditorContext* s_ctx = nullptr;
static uint32_t s_next_uid = 1;
static std::unordered_set<uint32_t> s_positioned;
// ── ID encoding ──────────────────────────────────────────────────────────────
// node id = editor_uid
// output pin id = (editor_uid << 8) | 0
// input pin id = (editor_uid << 8) | (slot + 1) slot 0..3
// link id = (from_node_uid << 20) | (to_node_uid << 8) | slot
static uintptr_t node_id(uint32_t uid) {
return static_cast<uintptr_t>(uid);
}
static uintptr_t output_pin_id(uint32_t uid) {
return (static_cast<uintptr_t>(uid) << 8) | 0u;
}
static uintptr_t input_pin_id(uint32_t uid, int slot) {
return (static_cast<uintptr_t>(uid) << 8) | static_cast<uintptr_t>(slot + 1);
}
static uintptr_t link_id(uint32_t from_uid, uint32_t to_uid, int slot) {
return (static_cast<uintptr_t>(from_uid) << 20)
| (static_cast<uintptr_t>(to_uid) << 8)
| static_cast<uintptr_t>(slot);
}
// Decode pin id back
static bool is_output_pin(uintptr_t id) { return (id & 0xFF) == 0; }
static uint32_t uid_from_pin(uintptr_t id) { return static_cast<uint32_t>(id >> 8); }
static int slot_from_input_pin(uintptr_t id) { return static_cast<int>(id & 0xFF) - 1; }
static int find_by_uid(const std::vector<DagStep>& p, uint32_t uid) {
for (int i = 0; i < static_cast<int>(p.size()); ++i) {
if (p[static_cast<size_t>(i)].editor_uid == uid) return i;
}
return -1;
}
static int find_by_id(const std::vector<DagStep>& p, const std::string& id) {
for (int i = 0; i < static_cast<int>(p.size()); ++i) {
if (p[static_cast<size_t>(i)].id == id) return i;
}
return -1;
}
static ImVec4 kind_color(DagKind kind) {
switch (kind) {
case DagKind::Gen: return ImVec4(0.25f, 0.55f, 0.90f, 1.0f);
case DagKind::Op: return ImVec4(0.65f, 0.40f, 0.90f, 1.0f);
case DagKind::Blend: return ImVec4(0.90f, 0.65f, 0.15f, 1.0f);
case DagKind::Output: return ImVec4(0.85f, 0.25f, 0.25f, 1.0f);
}
return ImVec4(1, 1, 1, 1);
}
static constexpr float PIN_RADIUS = 9.0f;
static constexpr float PIN_DIAMETER = PIN_RADIUS * 2.0f;
static const ImVec4 PIN_COLOR = ImVec4(0.78f, 0.78f, 0.82f, 1.0f);
static const ImVec4 PIN_BORDER = ImVec4(0.20f, 0.20f, 0.22f, 1.0f);
enum class PinSide { Input, Output };
// Draws a filled circle straddling the node's edge (half outside, half inside)
// and reserves only the inside half (PIN_RADIUS × PIN_DIAMETER) so the layout
// stays compact. The full circle is set as the pin's hit rect via ed::PinRect
// so the user can grab the protruding half.
static void draw_pin_circle(PinSide side) {
ImVec2 cursor = ImGui::GetCursorScreenPos();
float center_x = (side == PinSide::Input) ? cursor.x : cursor.x + PIN_RADIUS;
ImVec2 center(center_x, cursor.y + PIN_RADIUS);
ed::PinRect(ImVec2(center.x - PIN_RADIUS, center.y - PIN_RADIUS),
ImVec2(center.x + PIN_RADIUS, center.y + PIN_RADIUS));
ImDrawList* dl = ImGui::GetWindowDrawList();
dl->AddCircleFilled(center, PIN_RADIUS, ImGui::ColorConvertFloat4ToU32(PIN_COLOR));
dl->AddCircle(center, PIN_RADIUS, ImGui::ColorConvertFloat4ToU32(PIN_BORDER), 0, 1.5f);
ImGui::Dummy(ImVec2(PIN_RADIUS, PIN_DIAMETER));
}
// Topological sort using Kahn's algorithm.
// Returns false if a cycle is detected (should not happen — BeginCreate rejects cycles).
static bool topo_sort(std::vector<DagStep>& pipeline) {
int n = static_cast<int>(pipeline.size());
if (n == 0) return true;
// Build adjacency: edge from src -> dst if dst.source_ids[k] == src.id
std::unordered_map<std::string, int> id_to_idx;
for (int i = 0; i < n; ++i) id_to_idx[pipeline[static_cast<size_t>(i)].id] = i;
std::vector<int> in_degree(static_cast<size_t>(n), 0);
std::vector<std::vector<int>> adj(static_cast<size_t>(n));
for (int i = 0; i < n; ++i) {
const DagStep& s = pipeline[static_cast<size_t>(i)];
const DagNodeDef* def = dag_find(s.name);
int ni = def ? def->num_inputs : 0;
for (int k = 0; k < ni; ++k) {
const std::string& sid = s.source_ids[static_cast<size_t>(k)];
if (sid.empty()) continue;
auto it = id_to_idx.find(sid);
if (it == id_to_idx.end()) continue;
int src = it->second;
adj[static_cast<size_t>(src)].push_back(i);
in_degree[static_cast<size_t>(i)]++;
}
}
std::queue<int> q;
for (int i = 0; i < n; ++i) {
if (in_degree[static_cast<size_t>(i)] == 0) q.push(i);
}
std::vector<int> order;
order.reserve(static_cast<size_t>(n));
while (!q.empty()) {
int u = q.front(); q.pop();
order.push_back(u);
for (int v : adj[static_cast<size_t>(u)]) {
if (--in_degree[static_cast<size_t>(v)] == 0) q.push(v);
}
}
if (static_cast<int>(order.size()) != n) return false; // cycle
std::vector<DagStep> sorted;
sorted.reserve(static_cast<size_t>(n));
for (int idx : order) sorted.push_back(pipeline[static_cast<size_t>(idx)]);
// Force Output nodes to the back so all their dependencies live at smaller
// indices (compiler and cycle validator search strictly before the target).
std::stable_partition(sorted.begin(), sorted.end(), [](const DagStep& s) {
const DagNodeDef* d = dag_find(s.name);
return !(d && d->kind == DagKind::Output);
});
pipeline = std::move(sorted);
return true;
}
bool dag_node_editor(std::vector<DagStep>& pipeline) {
bool changed = false;
// Ensure UIDs are assigned (e.g. for nodes created before this editor was active)
for (auto& step : pipeline) {
if (step.editor_uid == 0) {
step.editor_uid = s_next_uid++;
}
}
// Create context on first call
if (!s_ctx) {
ed::Config cfg;
cfg.SettingsFile = nullptr; // no disk persistence
s_ctx = ed::CreateEditor(&cfg);
}
// Palette drop: detect without a capturing target (an InvisibleButton would
// steal clicks from the node editor). Observe the active drag-drop payload
// and, if the mouse is over this window and the user releases LMB, queue an
// add at that canvas position.
static std::string s_pending_add_name;
static ImVec2 s_pending_add_pos(0, 0);
static bool s_pending_add = false;
const bool window_hovered = ImGui::IsWindowHovered(
ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem);
if (window_hovered) {
if (const ImGuiPayload* p = ImGui::GetDragDropPayload()) {
if (p->IsDataType("DAG_NODE_TYPE") && ImGui::IsMouseReleased(ImGuiMouseButton_Left)) {
s_pending_add_name.assign(static_cast<const char*>(p->Data),
static_cast<size_t>(p->DataSize));
s_pending_add_pos = ImGui::GetMousePos();
s_pending_add = true;
}
}
}
ed::SetCurrentEditor(s_ctx);
ed::Begin("dag_editor", ImVec2(0.0f, 0.0f));
if (s_pending_add) {
const DagNodeDef* def = dag_find(s_pending_add_name);
if (def && static_cast<int>(pipeline.size()) < MAX_NODES) {
uint32_t uid = s_next_uid++;
DagStep step;
step.id = "n" + std::to_string(uid);
step.name = def->name;
step.params = def->param_defaults;
step.editor_uid = uid;
ImVec2 canvas_pos = ed::ScreenToCanvas(s_pending_add_pos);
step.editor_pos_x = canvas_pos.x;
step.editor_pos_y = canvas_pos.y;
// Insert before the Output node so the Output stays at the back;
// otherwise new nodes can never be wired into it (compiler and
// cycle check only search indices strictly before the target).
auto insert_it = pipeline.end();
for (auto it = pipeline.begin(); it != pipeline.end(); ++it) {
const DagNodeDef* d = dag_find(it->name);
if (d && d->kind == DagKind::Output) { insert_it = it; break; }
}
pipeline.insert(insert_it, step);
changed = true;
}
s_pending_add = false;
}
// ── Draw nodes ───────────────────────────────────────────────────────────
for (int i = 0; i < static_cast<int>(pipeline.size()); ++i) {
DagStep& step = pipeline[static_cast<size_t>(i)];
const DagNodeDef* def = dag_find(step.name);
if (!def) continue;
ImVec4 col = kind_color(def->kind);
// Initial position only — after that, the editor owns the node's position
// and user drags must not be overwritten.
if (s_positioned.find(step.editor_uid) == s_positioned.end()) {
if (step.editor_pos_x == 0.0f && step.editor_pos_y == 0.0f) {
step.editor_pos_x = 50.0f + static_cast<float>(i) * 220.0f;
step.editor_pos_y = 100.0f;
}
ed::SetNodePosition(ed::NodeId(node_id(step.editor_uid)),
ImVec2(step.editor_pos_x, step.editor_pos_y));
s_positioned.insert(step.editor_uid);
}
// Zero lateral padding so the input/output pin circles sit flush
// with the node's left and right edges.
ed::PushStyleVar(ed::StyleVar_NodePadding, ImVec4(0, 8, 0, 8));
ed::BeginNode(ed::NodeId(node_id(step.editor_uid)));
// Header (with horizontal padding so the title doesn't touch the edge)
ImGui::Dummy(ImVec2(8, 0));
ImGui::SameLine(0, 0);
ImGui::PushStyleColor(ImGuiCol_Text, col);
ImGui::TextUnformatted(def->label.c_str());
ImGui::PopStyleColor();
ImGui::Dummy(ImVec2(0, 4));
int ni = def->num_inputs;
bool has_output_pin = (def->kind != DagKind::Output);
// ── Three-column layout: inputs · controls · output ──────────
ImGui::BeginGroup(); // inputs column (left edge)
if (ni == 0) {
ImGui::Dummy(ImVec2(PIN_RADIUS, PIN_DIAMETER));
}
for (int k = 0; k < ni; ++k) {
ed::BeginPin(ed::PinId(input_pin_id(step.editor_uid, k)), ed::PinKind::Input);
ed::PinPivotAlignment(ImVec2(0.0f, 0.5f));
ed::PinPivotSize(ImVec2(0, 0));
draw_pin_circle(PinSide::Input);
ed::EndPin();
}
ImGui::EndGroup();
ImGui::SameLine(0, 8); // gap between pin column and controls
ImGui::BeginGroup(); // controls column (centre, with internal padding)
ImGui::PushID(static_cast<int>(step.editor_uid));
if (def->controls.empty() && def->kind != DagKind::Output) {
ImGui::Dummy(ImVec2(60, PIN_DIAMETER));
}
for (size_t ci = 0; ci < def->controls.size(); ++ci) {
const DagControl& ctrl = def->controls[ci];
ImGui::SetNextItemWidth(150.0f);
char uid_lbl[64];
std::snprintf(uid_lbl, sizeof(uid_lbl), "%s##%u%zu", ctrl.label.c_str(), step.editor_uid, ci);
if (ctrl.kind == DagControl::Kind::Slider) {
int pidx = ctrl.param_idx[0];
if (pidx >= 0 && pidx < 4) {
ImGui::SliderFloat(uid_lbl, &step.params[static_cast<size_t>(pidx)], ctrl.min, ctrl.max);
}
} else if (ctrl.kind == DagControl::Kind::XY) {
int px = ctrl.param_idx[0], py = ctrl.param_idx[1];
if (px >= 0 && px < 4 && py >= 0 && py < 4 && py == px + 1) {
ImGui::SliderFloat2(uid_lbl, &step.params[static_cast<size_t>(px)], ctrl.min, ctrl.max);
}
} else if (ctrl.kind == DagControl::Kind::Color) {
int pr = ctrl.param_idx[0];
if (pr >= 0 && pr + 2 < 4) {
ed::Suspend();
ImGui::ColorEdit3(uid_lbl, &step.params[static_cast<size_t>(pr)],
ImGuiColorEditFlags_NoInputs |
ImGuiColorEditFlags_NoLabel |
ImGuiColorEditFlags_AlphaBar);
ed::Resume();
}
}
}
ImGui::PopID();
ImGui::EndGroup();
ImGui::SameLine(0, 8); // gap between controls and output pin
ImGui::BeginGroup(); // output column (right edge)
if (has_output_pin) {
ed::BeginPin(ed::PinId(output_pin_id(step.editor_uid)), ed::PinKind::Output);
ed::PinPivotAlignment(ImVec2(1.0f, 0.5f));
ed::PinPivotSize(ImVec2(0, 0));
draw_pin_circle(PinSide::Output);
ed::EndPin();
} else {
ImGui::Dummy(ImVec2(PIN_RADIUS, PIN_DIAMETER));
}
ImGui::EndGroup();
ed::EndNode();
ed::PopStyleVar();
}
// ── Draw existing links ──────────────────────────────────────────────────
for (int i = 0; i < static_cast<int>(pipeline.size()); ++i) {
const DagStep& step = pipeline[static_cast<size_t>(i)];
const DagNodeDef* def = dag_find(step.name);
if (!def) continue;
for (int k = 0; k < def->num_inputs; ++k) {
const std::string& sid = step.source_ids[static_cast<size_t>(k)];
if (sid.empty()) continue;
int src_idx = find_by_id(pipeline, sid);
if (src_idx < 0) continue;
const DagStep& src_step = pipeline[static_cast<size_t>(src_idx)];
ed::Link(ed::LinkId(link_id(src_step.editor_uid, step.editor_uid, k)),
ed::PinId(output_pin_id(src_step.editor_uid)),
ed::PinId(input_pin_id(step.editor_uid, k)),
PIN_COLOR, 2.5f);
}
}
// ── Right-click on a link deletes it directly ──────────────────────────
{
ed::Suspend();
ed::LinkId ctx_lid;
if (ed::ShowLinkContextMenu(&ctx_lid)) {
uintptr_t raw = ctx_lid.Get();
uint32_t to_uid = static_cast<uint32_t>((raw >> 8) & 0xFFFu);
int slot = static_cast<int>(raw & 0xFFu);
int to_idx = find_by_uid(pipeline, to_uid);
if (to_idx >= 0 && slot >= 0 && slot < 4) {
pipeline[static_cast<size_t>(to_idx)].source_ids[static_cast<size_t>(slot)].clear();
changed = true;
}
}
ed::Resume();
}
// ── Right-click on a pin clears all connections of that pin ────────────
{
ed::Suspend();
ed::PinId ctx_pid;
if (ed::ShowPinContextMenu(&ctx_pid)) {
uintptr_t raw = ctx_pid.Get();
uint32_t uid = uid_from_pin(raw);
if (is_output_pin(raw)) {
// Output pin: clear every source_ids entry pointing to this node
int idx = find_by_uid(pipeline, uid);
if (idx >= 0) {
const std::string source_id = pipeline[static_cast<size_t>(idx)].id;
for (auto& s : pipeline) {
for (auto& sid : s.source_ids) {
if (sid == source_id) { sid.clear(); changed = true; }
}
}
}
} else {
// Input pin: clear that single slot
int slot = slot_from_input_pin(raw);
int idx = find_by_uid(pipeline, uid);
if (idx >= 0 && slot >= 0 && slot < 4) {
auto& sid = pipeline[static_cast<size_t>(idx)].source_ids[static_cast<size_t>(slot)];
if (!sid.empty()) { sid.clear(); changed = true; }
}
}
}
ed::Resume();
}
// ── Handle link creation ─────────────────────────────────────────────────
if (ed::BeginCreate()) {
ed::PinId start_pin, end_pin;
if (ed::QueryNewLink(&start_pin, &end_pin)) {
uintptr_t sp = start_pin.Get();
uintptr_t ep = end_pin.Get();
// Normalise: start must be output, end must be input
if (!is_output_pin(sp) && is_output_pin(ep)) {
std::swap(sp, ep);
}
bool valid = is_output_pin(sp) && !is_output_pin(ep);
if (valid) {
uint32_t from_uid = uid_from_pin(sp);
uint32_t to_uid = uid_from_pin(ep);
int slot = slot_from_input_pin(ep);
int from_idx = find_by_uid(pipeline, from_uid);
int to_idx = find_by_uid(pipeline, to_uid);
// Real cycle check: would the new edge from->to introduce a path
// from `from` back to itself? It does iff `from` already (transitively)
// depends on `to`. We walk source_ids of `from` and reject if we
// ever hit `to`. Vector index order is irrelevant — topo_sort runs
// at end-of-frame and reorders the pipeline.
bool cycle = false;
if (from_uid == to_uid) {
cycle = true;
} else if (from_idx >= 0 && to_idx >= 0) {
const std::string to_id = pipeline[static_cast<size_t>(to_idx)].id;
std::function<bool(const std::string&)> depends_on_to;
depends_on_to = [&](const std::string& node_id) -> bool {
if (node_id == to_id) return true;
int idx = -1;
for (int i = 0; i < static_cast<int>(pipeline.size()); ++i) {
if (pipeline[static_cast<size_t>(i)].id == node_id) { idx = i; break; }
}
if (idx < 0) return false;
const DagStep& s = pipeline[static_cast<size_t>(idx)];
const DagNodeDef* d = dag_find(s.name);
int n = d ? d->num_inputs : 0;
for (int k = 0; k < n; ++k) {
const std::string& sid = s.source_ids[static_cast<size_t>(k)];
if (!sid.empty() && depends_on_to(sid)) return true;
}
return false;
};
cycle = depends_on_to(pipeline[static_cast<size_t>(from_idx)].id);
}
if (cycle) {
ed::RejectNewItem(ImVec4(1, 0.3f, 0.3f, 1));
valid = false;
}
if (valid && from_idx >= 0 && to_idx >= 0 && slot >= 0) {
if (ed::AcceptNewItem()) {
pipeline[static_cast<size_t>(to_idx)].source_ids[static_cast<size_t>(slot)] =
pipeline[static_cast<size_t>(from_idx)].id;
changed = true;
}
}
} else {
ed::RejectNewItem(ImVec4(0.5f, 0.5f, 0.5f, 1));
}
}
}
ed::EndCreate();
// ── Handle deletion ──────────────────────────────────────────────────────
if (ed::BeginDelete()) {
ed::LinkId del_lid;
while (ed::QueryDeletedLink(&del_lid)) {
if (ed::AcceptDeletedItem()) {
uintptr_t raw = del_lid.Get();
uint32_t to_uid = static_cast<uint32_t>((raw >> 8) & 0xFFF);
int slot = static_cast<int>(raw & 0xFF);
int to_idx = find_by_uid(pipeline, to_uid);
if (to_idx >= 0 && slot < 4) {
pipeline[static_cast<size_t>(to_idx)].source_ids[static_cast<size_t>(slot)].clear();
changed = true;
}
}
}
ed::NodeId del_nid;
while (ed::QueryDeletedNode(&del_nid)) {
uint32_t uid = static_cast<uint32_t>(del_nid.Get());
int idx = find_by_uid(pipeline, uid);
// Refuse to delete the Output node (it's the sink)
const DagNodeDef* ddef = (idx >= 0) ? dag_find(pipeline[static_cast<size_t>(idx)].name) : nullptr;
if (ddef && ddef->kind == DagKind::Output) {
ed::RejectDeletedItem();
continue;
}
if (ed::AcceptDeletedItem()) {
if (idx >= 0) {
const std::string& del_step_id = pipeline[static_cast<size_t>(idx)].id;
for (auto& step : pipeline) {
for (auto& sid : step.source_ids) {
if (sid == del_step_id) sid.clear();
}
}
pipeline.erase(pipeline.begin() + idx);
changed = true;
}
}
}
}
ed::EndDelete();
// ── Save node positions back to steps ────────────────────────────────────
for (auto& step : pipeline) {
auto pos = ed::GetNodePosition(ed::NodeId(node_id(step.editor_uid)));
step.editor_pos_x = pos.x;
step.editor_pos_y = pos.y;
}
ed::End();
ed::SetCurrentEditor(nullptr);
// ── Topological sort after topology change ───────────────────────────────
if (changed) {
if (!topo_sort(pipeline)) {
// Cycle detected — should not happen given BeginCreate validation
// but log a warning and leave order as-is
std::fprintf(stderr, "dag_node_editor: cycle detected, skipping topo sort\n");
}
}
return changed;
}
void dag_node_editor_destroy() {
if (s_ctx) {
ed::DestroyEditor(s_ctx);
s_ctx = nullptr;
}
}
} // namespace fn::gfx