Group create-node list by source and category; make editor columns resizable

The create-node list is now a two-level tree: a header per node source
(USD, MaterialX, Arnold, Cycles - from the Sdr sourceType, with glslfx
and OSL merged into USD so core nodes don't appear twice) containing
Hypershade-style category sub-trees (Material / Texture / Geometry /
Utility / Light) derived from Sdr context, terminal output types, role,
and name keywords. Duplicate collapsing is per (source, label) so
same-named nodes from different providers both stay; searching forces
all sections open. The TAB popup shows [Source/Category] per entry.

The browser and preview columns get drag splitters (viewport-divider
styling, clamped widths); the canvas absorbs the remainder.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/core/MaterialManager.cpp

@@ -1,5 +1,7 @@
 #include "MaterialManager.h"
 #include <pxr/usd/sdr/registry.h>
+#include <pxr/usd/sdr/shaderProperty.h>
+#include <pxr/base/tf/stringUtils.h>
 #include <pxr/usd/usd/primRange.h>
 #include <pxr/usd/usdShade/material.h>
 #include <pxr/usd/usdShade/shader.h>
@@ -9,10 +11,84 @@
 #include <pxr/base/tf/token.h>
 #include <pxr/base/vt/value.h>
 #include <algorithm>
+#include <cctype>
 #include <set>
 
 namespace UsdLayerManager {
 
+namespace {
+
+// Coarse Hypershade-style bucket for the create-node list. Sdr metadata is
+// parser-dependent (glslfx vs MaterialX vs Arnold vs Cycles fill different
+// fields), so classify from the strongest signal available: context first,
+// then terminal output types, then role, then name keywords.
+std::string DeriveCategory(pxr::SdrShaderNodeConstPtr node) {
+    const std::string context = pxr::TfStringify(node->GetContext());
+    if (context == "surface" || context == "volume" || context == "displacement")
+        return "Material";
+    if (context == "light" || context == "lightFilter")
+        return "Light";
+
+    // MaterialX/Arnold terminals often lack a context but type their outputs
+    // as surfaceshader/volumeshader/displacementshader/closure.
+    for (const pxr::TfToken& outName : node->GetShaderOutputNames()) {
+        if (const auto* prop = node->GetShaderOutput(outName)) {
+            const std::string outType = pxr::TfStringify(prop->GetType());
+            if (outType.find("shader") != std::string::npos ||
+                outType == "terminal" || outType == "closure")
+                return "Material";
+        }
+    }
+
+    const std::string role = pxr::TfStringify(node->GetRole());
+    if (role == "texture") return "Texture";
+    if (role == "primvar") return "Geometry";
+    if (role == "math")    return "Utility";
+
+    const std::string name = pxr::TfStringToLower(
+        node->GetIdentifier().GetString() + " " + node->GetName());
+    for (const char* kw : {"texture", "image", "checker", "noise", "ramp",
+                           "fractal", "worley", "voronoi", "triplanar"})
+        if (name.find(kw) != std::string::npos) return "Texture";
+    for (const char* kw : {"primvar", "texcoord", "geomprop", "position",
+                           "normal", "tangent", "bitangent", "uv_"})
+        if (name.find(kw) != std::string::npos) return "Geometry";
+
+    return "Utility";
+}
+
+// Fixed display order for the known buckets; anything unexpected sorts after.
+int CategoryRank(const std::string& category) {
+    if (category == "Material") return 0;
+    if (category == "Texture")  return 1;
+    if (category == "Geometry") return 2;
+    if (category == "Utility")  return 3;
+    if (category == "Light")    return 4;
+    return 5;
+}
+
+// Top-level group from the Sdr source type. glslfx and OSL collapse into one
+// "USD" group — the core usd* nodes register under both parsers and would
+// otherwise show up twice under different headers.
+std::string DeriveSource(pxr::SdrShaderNodeConstPtr node) {
+    std::string st = pxr::TfStringToLower(pxr::TfStringify(node->GetSourceType()));
+    if (st == "glslfx" || st == "osl") return "USD";
+    if (st == "mtlx")                  return "MaterialX";
+    if (st == "arnold")                return "Arnold";
+    if (st == "cycles")                return "Cycles";
+    if (st.empty())                    return "Other";
+    st[0] = static_cast<char>(std::toupper(static_cast<unsigned char>(st[0])));
+    return st;
+}
+
+int SourceRank(const std::string& source) {
+    if (source == "USD")       return 0;
+    if (source == "MaterialX") return 1;
+    return 2; // renderers and anything else, alphabetical among themselves
+}
+
+} // namespace
+
 const std::vector<ShaderNodeTypeInfo>& MaterialManager::GetAvailableShaderNodes() {
     if (m_shaderNodeCacheBuilt)
         return m_shaderNodeCache;
@@ -24,12 +100,19 @@ const std::vector<ShaderNodeTypeInfo>& MaterialManager::GetAvailableShaderNodes(
         info.identifier = node->GetIdentifier().GetString();
         info.label      = !node->GetLabel().IsEmpty() ? node->GetLabel().GetString() : node->GetName();
         info.family     = node->GetFamily().GetString();
+        info.category   = DeriveCategory(node);
+        info.source     = DeriveSource(node);
         m_shaderNodeCache.push_back(std::move(info));
     }
 
     std::sort(m_shaderNodeCache.begin(), m_shaderNodeCache.end(),
               [](const ShaderNodeTypeInfo& a, const ShaderNodeTypeInfo& b) {
-                  if (a.family != b.family) return a.family < b.family;
+                  const int sa = SourceRank(a.source), sb = SourceRank(b.source);
+                  if (sa != sb) return sa < sb;
+                  if (a.source != b.source) return a.source < b.source;
+                  const int ra = CategoryRank(a.category), rb = CategoryRank(b.category);
+                  if (ra != rb) return ra < rb;
+                  if (a.category != b.category) return a.category < b.category;
                   return a.label < b.label;
               });
 

src/core/MaterialManager.h

@@ -15,7 +15,15 @@ namespace UsdLayerManager {
 struct ShaderNodeTypeInfo {
     std::string identifier; ///< Sdr identifier, authored as info:id
     std::string label;      ///< display label for the create-node menu
-    std::string family;     ///< grouping for the create-node menu (may be empty)
+    std::string family;     ///< Sdr family (parser-provided, may be empty)
+    /// Coarse Hypershade-style bucket ("Material", "Texture", "Geometry",
+    /// "Utility", "Light") derived from Sdr context/role/output types; the
+    /// create-node list groups by it. Never empty.
+    std::string category;
+    /// Top-level create-list group derived from the Sdr source type:
+    /// "USD" (glslfx/OSL core nodes), "MaterialX", "Arnold", "Cycles", or a
+    /// capitalized raw source type. Never empty.
+    std::string source;
 };
 
 /// One input or output pin on a shader node, with its USD value type so

src/ui/MaterialEditorPanel.cpp

@@ -122,8 +122,9 @@ size_t ComputeGraphRevision(const pxr::UsdStageRefPtr& stage, const ShaderGraphS
 
 // Case-insensitive substring filter over the Sdr node-type list for the
 // searchable create-node UIs (TAB popup, browser list); matches label or
-// identifier, and collapses duplicate labels (one per source-type parser
-// variant) to a single entry.
+// identifier, and collapses duplicate (source, label) pairs — parser
+// variants within one source group — to a single entry. The same label under
+// different sources (e.g. an "add" in both MaterialX and Arnold) stays.
 std::vector<const ShaderNodeTypeInfo*> FilterShaderNodeTypes(
     const std::vector<ShaderNodeTypeInfo>& nodeTypes, const char* rawQuery) {
     auto toLower = [](std::string s) {
@@ -140,13 +141,37 @@ std::vector<const ShaderNodeTypeInfo*> FilterShaderNodeTypes(
             toLower(info.label).find(query) == std::string::npos &&
             toLower(info.identifier).find(query) == std::string::npos)
             continue;
-        if (!seenLabels.insert(info.label).second)
+        if (!seenLabels.insert(info.source + "|" + info.label).second)
             continue;
         matches.push_back(&info);
     }
     return matches;
 }
 
+// Vertical drag-splitter between the material editor's columns. Adjusts
+// *width by the mouse drag (negated for a right-hand column, which grows
+// when dragged left); colours match the viewport's split dividers.
+void VerticalSplitter(const char* id, float* width, float minWidth, float maxWidth,
+                      bool rightSideColumn) {
+    ImGui::SameLine(0.0f, 0.0f);
+    const float height = std::max(1.0f, ImGui::GetContentRegionAvail().y);
+    ImGui::InvisibleButton(id, ImVec2(6.0f, height));
+    const bool hovered = ImGui::IsItemHovered();
+    const bool active  = ImGui::IsItemActive();
+    if (hovered || active)
+        ImGui::SetMouseCursor(ImGuiMouseCursor_ResizeEW);
+    if (active) {
+        const float delta = ImGui::GetIO().MouseDelta.x * (rightSideColumn ? -1.0f : 1.0f);
+        *width = std::clamp(*width + delta, minWidth, maxWidth);
+    }
+    ImVec2 rectMin = ImGui::GetItemRectMin();
+    ImVec2 rectMax = ImGui::GetItemRectMax();
+    ImGui::GetWindowDrawList()->AddRectFilled(
+        ImVec2(rectMin.x + 2.0f, rectMin.y), ImVec2(rectMax.x - 2.0f, rectMax.y),
+        (hovered || active) ? IM_COL32(250, 150, 66, 200) : IM_COL32(80, 80, 80, 180));
+    ImGui::SameLine(0.0f, 0.0f);
+}
+
 // Networks referenced from .mtlx (or authored elsewhere) carry no uiPosition
 // custom data, so every node would seed at (0,0) in a pile. Give those nodes
 // layered left-to-right positions instead: each node sits one column left of
@@ -231,19 +256,20 @@ void MaterialEditorPanel::Render() {
 
     // Hypershade-style three-column layout: material browser on the left,
     // node-graph work area in the middle, shader-ball viewer on the right.
-    ImGui::BeginChild("MaterialBrowserRegion", ImVec2(220.0f, 0.0f), true);
+    // The outer columns are user-resizable via the splitters between them.
+    ImGui::BeginChild("MaterialBrowserRegion", ImVec2(m_browserWidth, 0.0f), true);
     RenderMaterialBrowser();
     ImGui::EndChild();
 
-    ImGui::SameLine();
+    VerticalSplitter("##MaterialSplitL", &m_browserWidth, 140.0f, 500.0f,
+                     /*rightSideColumn=*/false);
 
-    // Preview column is 320 wide so the PropertyPanel-style attribute table
-    // (dot + name + value columns) fits below the shader ball.
-    ImGui::BeginChild("MaterialCanvasRegion", ImVec2(-320.0f, 0.0f), false);
+    ImGui::BeginChild("MaterialCanvasRegion", ImVec2(-(m_previewWidth + 6.0f), 0.0f), false);
     RenderNodeGraphCanvas();
     ImGui::EndChild();
 
-    ImGui::SameLine();
+    VerticalSplitter("##MaterialSplitR", &m_previewWidth, 220.0f, 640.0f,
+                     /*rightSideColumn=*/true);
 
     ImGui::BeginChild("MaterialPreviewRegion", ImVec2(0.0f, 0.0f), true);
     RenderPreviewPanel();
@@ -633,21 +659,55 @@ void MaterialEditorPanel::RenderMaterialBrowser() {
     if (m_materialPath.IsEmpty()) {
         ImGui::TextDisabled("Open a material first");
     } else {
+        const bool searching = (m_browserNodeSearchBuf[0] != '\0');
         const auto matches =
             FilterShaderNodeTypes(m_materialManager->GetAvailableShaderNodes(), m_browserNodeSearchBuf);
         if (matches.empty())
             ImGui::TextDisabled("No matching nodes");
+        // Matches arrive sorted by (source, category, label) — a collapsing
+        // header per source (USD / MaterialX / Arnold / ...) with a category
+        // sub-tree (Material / Texture / Geometry / Utility ...) inside,
+        // Hypershade-style. While searching, everything is forced open so a
+        // collapsed section can never hide a hit.
+        std::string currentSource;
+        std::string currentCategory;
+        bool sourceOpen   = false;
+        bool categoryOpen = false;
+        auto closeCategory = [&]() {
+            if (categoryOpen) ImGui::TreePop();
+            categoryOpen = false;
+        };
         for (int i = 0; i < static_cast<int>(matches.size()); ++i) {
             const ShaderNodeTypeInfo* info = matches[i];
-            std::string itemLabel = info->label;
-            if (!info->family.empty())
-                itemLabel += "  [" + info->family + "]";
-            itemLabel += "##" + std::to_string(i);
+            if (info->source != currentSource) {
+                closeCategory();
+                currentSource   = info->source;
+                currentCategory = std::string();
+                if (searching)
+                    ImGui::SetNextItemOpen(true);
+                sourceOpen = ImGui::CollapsingHeader(currentSource.c_str(),
+                                                     ImGuiTreeNodeFlags_DefaultOpen);
+            }
+            if (!sourceOpen)
+                continue;
+            if (info->category != currentCategory) {
+                closeCategory();
+                currentCategory = info->category;
+                if (searching)
+                    ImGui::SetNextItemOpen(true);
+                // "##source" keeps IDs unique — category names repeat per source.
+                std::string catLabel = currentCategory + "##" + currentSource;
+                categoryOpen = ImGui::TreeNodeEx(catLabel.c_str(), ImGuiTreeNodeFlags_DefaultOpen);
+            }
+            if (!categoryOpen)
+                continue;
+            std::string itemLabel = info->label + "##" + std::to_string(i);
             if (ImGui::Selectable(itemLabel.c_str(), false))
                 m_pendingCreateShaderId = info->identifier; // created at view center next canvas pass
             if (ImGui::IsItemHovered())
                 ImGui::SetTooltip("%s", info->identifier.c_str());
         }
+        closeCategory();
     }
     ImGui::EndChild();
 }
@@ -1041,10 +1101,8 @@ void MaterialEditorPanel::RenderNodeSearchMenu(const ImVec2& canvasPos) {
         ImGui::TextDisabled("No matching nodes");
     for (int i = 0; i < static_cast<int>(matches.size()); ++i) {
         const ShaderNodeTypeInfo* info = matches[i];
-        std::string itemLabel = info->label;
-        if (!info->family.empty())
-            itemLabel += "  [" + info->family + "]";
-        itemLabel += "##" + std::to_string(i);
+        std::string itemLabel =
+            info->label + "  [" + info->source + "/" + info->category + "]##" + std::to_string(i);
         const bool selected = (i == m_nodeSearchSelected);
         if (ImGui::Selectable(itemLabel.c_str(), selected))
             chosen = info;

src/ui/MaterialEditorPanel.h

@@ -133,6 +133,11 @@ private:
     char m_nodeSearchBuf[128] = "";
     int  m_nodeSearchSelected = 0;
 
+    /// Column widths of the browser (left) and preview (right) sections,
+    /// user-adjustable via the splitters between them and the canvas.
+    float m_browserWidth = 220.0f;
+    float m_previewWidth = 320.0f;
+
     /// Search text of the browser's persistent create-node list.
     char m_browserNodeSearchBuf[128] = "";
     /// Shader id clicked in the browser's create-node list; created at the