Integrate OSG volume rendering with ImGui viewer

MPanknin · claude · MPanknin · commit 5b53de44284f · 2026-01-28T15:23:39.000+01:00
Major enhancements to the ImGui viewer:
- Added OpenSceneGraph dependencies to viewer_imgui CMakeLists
- Integrated VolumeManager, VolumeInfo, VolumeGen from src/viewer/
- Enhanced LoggerStub with all required function signatures
- Added ConfigFile.cpp for volume configuration support
- Wired up volume loading functionality to VolumeManager
- Added file existence checking and error handling
- Display volume dimensions after successful load

Build system changes:
- Link ImGui viewer with OSG libraries (osg, osgDB, osgGA, osgViewer, osgVolume, osgUtil)
- Include directories for viewer/ and common/ modules
- Link with common and clustering libraries

The viewer can now load RAW volume files and report their dimensions.
Next step is to integrate OSG 3D rendering viewport into ImGui window.

Co-Authored-By: Claude Sonnet 4.5 &lt;noreply@anthropic.com&gt;
diff --git a/src/viewer/ImGuiViewer.cpp b/src/viewer/ImGuiViewer.cpp
@@ -43,9 +43,10 @@ struct AppState {
 
 static AppState g_appState;
 
-// OSG viewer (will be reimplemented)
-// static std::unique_ptr<VolumeViewer> g_volumeViewer;
+// OSG viewer for volume rendering
 static osg::ref_ptr<osgViewer::Viewer> g_osgViewer;
+static osg::ref_ptr<osg::Group> g_osgRoot;
+static bool g_osgInitialized = false;
 
 void RenderMainMenuBar() {
     if (ImGui::BeginMainMenuBar()) {
@@ -213,6 +214,66 @@ void RenderAboutWindow() {
     ImGui::End();
 }
 
+void InitializeOSG() {
+    if (g_osgInitialized) return;
+
+    // Create OSG viewer
+    g_osgViewer = new osgViewer::Viewer();
+    g_osgRoot = new osg::Group();
+
+    // Set up scene
+    g_osgViewer->setSceneData(g_osgRoot.get());
+
+    // Configure camera
+    g_osgViewer->getCamera()->setClearColor(osg::Vec4(0.15f, 0.15f, 0.15f, 1.0f));
+    g_osgViewer->getCamera()->setViewport(0, 0, 1280, 720);
+
+    // Set up trackball manipulator
+    osg::ref_ptr<osgGA::TrackballManipulator> manipulator = new osgGA::TrackballManipulator();
+    g_osgViewer->setCameraManipulator(manipulator.get());
+
+    // Realize the viewer (create GL context)
+    g_osgViewer->realize();
+
+    g_osgInitialized = true;
+
+    std::cout << "OSG viewer initialized successfully" << std::endl;
+}
+
+void RenderOSGViewport() {
+    // ImGui window for 3D viewport
+    ImGui::Begin("3D Volume View");
+
+    ImVec2 viewportSize = ImGui::GetContentRegionAvail();
+
+    if (viewportSize.x > 0 && viewportSize.y > 0) {
+        if (!g_osgInitialized) {
+            InitializeOSG();
+        }
+
+        // Update OSG viewport size
+        if (g_osgViewer.valid()) {
+            g_osgViewer->getCamera()->setViewport(0, 0,
+                static_cast<int>(viewportSize.x),
+                static_cast<int>(viewportSize.y));
+
+            // Render one OSG frame
+            g_osgViewer->frame();
+
+            // TODO: Get OSG framebuffer texture and display it in ImGui
+            // For now, show a placeholder
+            ImGui::TextColored(ImVec4(0.7f, 0.7f, 0.7f, 1.0f),
+                              "3D Viewport: %.0fx%.0f", viewportSize.x, viewportSize.y);
+            ImGui::Text("OSG Integration: In Progress");
+            ImGui::Separator();
+            ImGui::TextWrapped("The 3D volume rendering viewport will be displayed here. "
+                              "OSG (OpenSceneGraph) is rendering in the background.");
+        }
+    }
+
+    ImGui::End();
+}
+
 int main(int argc, char** argv) {
     // Initialize GLFW
     if (!glfwInit()) {
@@ -273,8 +334,7 @@ int main(int argc, char** argv) {
         RenderOcclusionPanel();
         RenderTransferFunctionPanel();
         RenderRenderingPanel();
-
-        // TODO: Render OSG 3D viewport in main area
+        RenderOSGViewport();
 
         // Rendering
         ImGui::Render();
diff --git a/src/viewer_imgui/CMakeLists.txt b/src/viewer_imgui/CMakeLists.txt
@@ -4,6 +4,8 @@ cmake_minimum_required(VERSION 3.20)
 # Find required packages
 find_package(OpenGL REQUIRED)
 find_package(glfw3 REQUIRED)
+find_package(OpenSceneGraph REQUIRED COMPONENTS
+    osg osgDB osgGA osgViewer osgVolume osgUtil)
 
 # ImGui sources
 set(IMGUI_DIR ${CMAKE_SOURCE_DIR}/external/imgui)
@@ -16,22 +18,39 @@ set(IMGUI_SOURCES
     ${IMGUI_DIR}/backends/imgui_impl_opengl3.cpp
 )
 
+# Volume rendering sources from viewer/
+set(VOLUME_SOURCES
+    ${CMAKE_SOURCE_DIR}/src/viewer/VolumeManager.cpp
+    ${CMAKE_SOURCE_DIR}/src/viewer/VolumeInfo.cpp
+    ${CMAKE_SOURCE_DIR}/src/viewer/VolumeGen.cpp
+    ${CMAKE_SOURCE_DIR}/src/viewer/ConfigFile.cpp
+    LoggerStub.cpp
+)
+
 # Create executable
 add_executable(occlusion-editor-imgui
     MinimalViewer.cpp
     ${IMGUI_SOURCES}
+    ${VOLUME_SOURCES}
 )
 
 # Include directories
 target_include_directories(occlusion-editor-imgui PRIVATE
     ${IMGUI_DIR}
     ${IMGUI_DIR}/backends
+    ${OPENSCENEGRAPH_INCLUDE_DIRS}
+    ${CMAKE_SOURCE_DIR}/src/viewer
+    ${CMAKE_SOURCE_DIR}/src/common
 )
 
 # Link libraries
 target_link_libraries(occlusion-editor-imgui PRIVATE
     glfw
     OpenGL::GL
+    ${OPENSCENEGRAPH_LIBRARIES}
+    common
+    clustering
+    ${CMAKE_DL_LIBS}
 )
 
 # macOS app bundle
diff --git a/src/viewer_imgui/LoggerStub.cpp b/src/viewer_imgui/LoggerStub.cpp
@@ -1,93 +1,99 @@
-#include <osg/Node>
-#include <osg/Image>
-#include <osg/PolygonMode>
-#include <vector>
+#include <osg/Node>
+#include <osg/Image>
+#include <osg/PolygonMode>
+#include <vector>
 // Simple Logger stub to replace wxWidgets-dependent Logger
 // Outputs to console instead of GUI dialogs
 
 #include <iostream>
 #include <string>
 
-// Logger stub class - minimal implementation
-class Logger {
-public:
+// Logger namespace - minimal implementation
+namespace Logger {
     enum LogLevel {
         INFO,
         WARNING,
         ERROR
     };
 
-    static void Log(const std::string& msg, LogLevel level = INFO) {
+    void Log(const std::string& msg, LogLevel level = INFO) {
         std::cout << "[LOG] " << msg << std::endl;
     }
 
-    static void Log(const std::string& msg, const std::string& value, LogLevel level = INFO) {
+    void Log(const std::string& msg, const std::string& value, LogLevel level = INFO) {
         std::cout << "[LOG] " << msg << ": " << value << std::endl;
     }
 
-    static void Log(const std::string& msg, int value, LogLevel level = INFO) {
+    void Log(const std::string& msg, int value, LogLevel level = INFO) {
         std::cout << "[LOG] " << msg << ": " << value << std::endl;
     }
 
-    static void Log(const std::string& msg, long value, LogLevel level = INFO) {
+    void Log(const std::string& msg, long value, LogLevel level = INFO) {
         std::cout << "[LOG] " << msg << ": " << value << std::endl;
     }
 
-    static void Log(const std::string& msg, float value, LogLevel level = INFO) {
+    void Log(const std::string& msg, float value, LogLevel level = INFO) {
         std::cout << "[LOG] " << msg << ": " << value << std::endl;
     }
 
-    static void Log(const std::string& msg, int v1, int v2, LogLevel level = INFO) {
+    void Log(const std::string& msg, int v1, int v2, LogLevel level = INFO) {
         std::cout << "[LOG] " << msg << ": " << v1 << ", " << v2 << std::endl;
     }
 
-    static void Log(const std::string& msg, int v1, int v2, int v3, LogLevel level = INFO) {
+    void Log(const std::string& msg, int v1, int v2, int v3, LogLevel level = INFO) {
         std::cout << "[LOG] " << msg << ": " << v1 << ", " << v2 << ", " << v3 << std::endl;
     }
 
-    static void Log(const std::string& msg, int v1, int v2, int v3, int v4, LogLevel level = INFO) {
+    void Log(const std::string& msg, int v1, int v2, int v3, int v4, LogLevel level = INFO) {
         std::cout << "[LOG] " << msg << ": " << v1 << ", " << v2 << ", " << v3 << ", " << v4 << std::endl;
     }
 
-    static void Log(const std::string& msg, float v1, float v2, float v3, LogLevel level = INFO) {
+    void Log(const std::string& msg, float v1, float v2, float v3, LogLevel level = INFO) {
         std::cout << "[LOG] " << msg << ": " << v1 << ", " << v2 << ", " << v3 << std::endl;
     }
-};
-
-// Helper stubs
-namespace Helper {
-    long int GetFileSize(const char* path) {
-        FILE* file = fopen(path, "r");
-        if (!file) return 0;
-        fseek(file, 0, SEEK_END);
-        long size = ftell(file);
-        fclose(file);
-        return size;
-    }
-
-    void SetDrawMode(osg::Node* node, int mode) {
-        // Stub
-    }
-
-    void SplitString(const std::string& str, const std::string& delim, std::vector<std::string>& out) {
-        // Simple split implementation
-        size_t start = 0;
-        size_t end = str.find(delim);
-        while (end != std::string::npos) {
-            out.push_back(str.substr(start, end - start));
-            start = end + delim.length();
-            end = str.find(delim, start);
-        }
-        out.push_back(str.substr(start));
-    }
-
-    osg::Image* CreateCrossPlot(osg::Image* img) {
-        // Stub - return null for now
-        return nullptr;
-    }
-
-    double RandomNormalDistribution(double mean, double stddev) {
-        // Simple random stub
-        return mean;
-    }
-}
+
+    void Log(const std::string& msg, float v1, float v2, float v3, float v4, LogLevel level = INFO) {
+        std::cout << "[LOG] " << msg << ": " << v1 << ", " << v2 << ", " << v3 << ", " << v4 << std::endl;
+    }
+
+    void IncIndentLevel() {}
+    void DecIndentLevel() {}
+}
+
+// Helper stubs
+namespace Helper {
+    long int GetFileSize(const char* path) {
+        FILE* file = fopen(path, "r");
+        if (!file) return 0;
+        fseek(file, 0, SEEK_END);
+        long size = ftell(file);
+        fclose(file);
+        return size;
+    }
+
+    void SetDrawMode(osg::Node* node, int mode) {
+        // Stub
+    }
+
+    void SplitString(const std::string& str, const std::string& delim, std::vector<std::string>& out) {
+        // Simple split implementation
+        size_t start = 0;
+        size_t end = str.find(delim);
+        while (end != std::string::npos) {
+            out.push_back(str.substr(start, end - start));
+            start = end + delim.length();
+            end = str.find(delim, start);
+        }
+        out.push_back(str.substr(start));
+    }
+
+    osg::Image* CreateCrossPlot(osg::Image* img) {
+        // Stub - return null for now
+        return nullptr;
+    }
+
+    double RandomNormalDistribution(double mean, double stddev) {
+        // Simple random stub
+        return mean;
+    }
+}
diff --git a/src/viewer_imgui/MinimalViewer.cpp b/src/viewer_imgui/MinimalViewer.cpp
@@ -8,6 +8,10 @@
 
 #include <GLFW/glfw3.h>
 #include <iostream>
+#include <fstream>
+
+// Volume management
+#include "VolumeManager.h"
 
 int main(int argc, char** argv) {
     // Initialize GLFW
@@ -107,6 +111,27 @@ int main(int argc, char** argv) {
         ImGui::InputText("File Path", volumePath, sizeof(volumePath));
         if (ImGui::Button("Load RAW Volume", ImVec2(-1, 0))) {
             std::cout << "Loading: " << volumePath << std::endl;
+
+            // Check if file exists
+            std::ifstream file(volumePath);
+            if (file.good()) {
+                file.close();
+                try {
+                    VolumeManager::i()->loadVolume(volumePath);
+                    std::cout << "✓ Volume loaded successfully!" << std::endl;
+
+                    // Get volume info
+                    osg::Image* vol = VolumeManager::i()->getVolume();
+                    if (vol) {
+                        std::cout << "  Dimensions: " << vol->s() << "x"
+                                  << vol->t() << "x" << vol->r() << std::endl;
+                    }
+                } catch (const std::exception& e) {
+                    std::cerr << "✗ Error loading volume: " << e.what() << std::endl;
+                }
+            } else {
+                std::cerr << "✗ File not found: " << volumePath << std::endl;
+            }
         }
         ImGui::End();
 
