Add ImPlot (#352)

nmwsharp · web-flow · commit aba50436d7d1 · 2025-07-23T00:50:24.000-07:00
* basic implot setup

* clean up implot context management, add some tests

* more context cleanup

* add unfortunate note about screenshot not fully working

* add implot to demo
diff --git a/.gitmodules b/.gitmodules
@@ -12,3 +12,6 @@
 [submodule "deps/glm"]
 	path = deps/glm
 	url = https://github.com/g-truc/glm.git
+[submodule "deps/imgui/implot"]
+	path = deps/imgui/implot
+	url = https://github.com/epezent/implot
diff --git a/deps/imgui/CMakeLists.txt b/deps/imgui/CMakeLists.txt
@@ -19,14 +19,22 @@ endif()
 
 if("${POLYSCOPE_BACKEND_OPENGL3_GLFW}")
 
-  set(SRCS imgui/imgui.cpp imgui/imgui_draw.cpp imgui/imgui_tables.cpp imgui/imgui_widgets.cpp imgui/imgui_demo.cpp imgui/backends/imgui_impl_glfw.cpp imgui/backends/imgui_impl_opengl3.cpp)
+  # imgui sources
+  list(APPEND SRCS imgui/imgui.cpp imgui/imgui_draw.cpp imgui/imgui_tables.cpp imgui/imgui_widgets.cpp imgui/imgui_demo.cpp imgui/backends/imgui_impl_glfw.cpp imgui/backends/imgui_impl_opengl3.cpp)
+
+  # implot sources
+  list(APPEND SRCS 
+          implot/implot.cpp
+          implot/implot_items.cpp
+      )
 
   add_library(
           imgui
           ${SRCS}
           )
 
   target_include_directories(imgui PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/imgui/")
+  target_include_directories(imgui PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/implot/")
   target_include_directories(imgui PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/../glfw/include/")
   target_include_directories(imgui PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/../glad/include/")
 
diff --git a/deps/imgui/implot b/deps/imgui/implot
@@ -0,0 +1 @@
+Subproject commit 3da8bd34299965d3b0ab124df743fe3e076fa222
diff --git a/examples/demo-app/demo_app.cpp b/examples/demo-app/demo_app.cpp
@@ -92,7 +92,8 @@ void constructDemoCurveNetwork(std::string curveName, std::vector<glm::vec3> nod
       valYabs[iE] = std::fabs(midpointPos.y);
     }
     polyscope::getCurveNetwork(curveName)->addEdgeScalarQuantity("edge len", edgeLen, polyscope::DataType::MAGNITUDE);
-    polyscope::getCurveNetwork(curveName)->addEdgeScalarQuantity("edge valYabs", valYabs, polyscope::DataType::MAGNITUDE);
+    polyscope::getCurveNetwork(curveName)->addEdgeScalarQuantity("edge valYabs", valYabs,
+                                                                 polyscope::DataType::MAGNITUDE);
     polyscope::getCurveNetwork(curveName)->addEdgeScalarQuantity("edge categorical", valEdgeCat,
                                                                  polyscope::DataType::CATEGORICAL);
     polyscope::getCurveNetwork(curveName)->addEdgeColorQuantity("eColor", randColor);
@@ -845,6 +846,9 @@ void callback() {
     }
   }
 
+  if (ImGui::Button("nested show")) {
+    polyscope::show();
+  }
 
   if (ImGui::Button("drop camera view here")) {
     dropCameraView();
@@ -858,9 +862,28 @@ void callback() {
     addVolumeGrid();
   }
 
+  // ImPlot
+  // dummy data
+  if (ImGui::TreeNode("ImPlot")) {
+
+    std::vector<float> plotVals;
+    for (float t = 0; t < 10.; t += 0.01) {
+      plotVals.push_back(std::cosf(t + ImGui::GetTime()));
+    }
+
+    // sample plot
+    if (ImPlot::BeginPlot("test plot")) {
+      ImPlot::PlotLine("sample_val", &plotVals.front(), plotVals.size());
+      ImPlot::EndPlot();
+    }
+
+    ImGui::TreePop();
+  }
+
   ImGui::PopItemWidth();
 }
 
+
 int main(int argc, char** argv) {
   // Configure the argument parser
   args::ArgumentParser parser("A simple demo of Polyscope.\nBy "
diff --git a/include/polyscope/polyscope.h b/include/polyscope/polyscope.h
@@ -9,6 +9,7 @@
 #include <unordered_set>
 
 #include "imgui.h"
+#include "implot.h"
 
 #include "polyscope/context.h"
 #include "polyscope/group.h"
diff --git a/src/polyscope.cpp b/src/polyscope.cpp
@@ -8,6 +8,7 @@
 #include <thread>
 
 #include "imgui.h"
+#include "implot.h"
 
 #include "polyscope/options.h"
 #include "polyscope/pick.h"
@@ -33,6 +34,7 @@ namespace {
 // initialization.
 struct ContextEntry {
   ImGuiContext* context;
+  ImPlotContext* plotContext;
   std ::function<void()> callback;
   bool drawDefaultUI;
 };
@@ -183,7 +185,7 @@ void init(std::string backend) {
 
   // Create an initial context based context. Note that calling show() never actually uses this context, because it
   // pushes a new one each time. But using frameTick() may use this context.
-  contextStack.push_back(ContextEntry{ImGui::GetCurrentContext(), nullptr, true});
+  contextStack.push_back(ContextEntry{ImGui::GetCurrentContext(), ImPlot::GetCurrentContext(), nullptr, true});
 
   view::invalidateView();
 
@@ -205,11 +207,13 @@ void pushContext(std::function<void()> callbackFunction, bool drawDefaultUI) {
 
   // Create a new context and push it on to the stack
   ImGuiContext* newContext = ImGui::CreateContext();
+  ImPlotContext* newPlotContext = ImPlot::CreateContext();
   ImGuiIO& oldIO = ImGui::GetIO(); // used to GLFW + OpenGL data to the new IO object
 #ifdef IMGUI_HAS_DOCK
   ImGuiPlatformIO& oldPlatformIO = ImGui::GetPlatformIO();
 #endif
   ImGui::SetCurrentContext(newContext);
+  ImPlot::SetCurrentContext(newPlotContext);
 #ifdef IMGUI_HAS_DOCK
   // Propagate GLFW window handle to new context
   ImGui::GetMainViewport()->PlatformHandle = oldPlatformIO.Viewports[0]->PlatformHandle;
@@ -219,7 +223,8 @@ void pushContext(std::function<void()> callbackFunction, bool drawDefaultUI) {
 
   render::engine->configureImGui();
 
-  contextStack.push_back(ContextEntry{newContext, callbackFunction, drawDefaultUI});
+
+  contextStack.push_back(ContextEntry{newContext, newPlotContext, callbackFunction, drawDefaultUI});
 
   if (contextStack.size() > 50) {
     // Catch bugs with nested show()
@@ -259,14 +264,17 @@ void pushContext(std::function<void()> callbackFunction, bool drawDefaultUI) {
   // Workaround overzealous ImGui assertion before destroying any inner context
   // https://github.com/ocornut/imgui/pull/7175
   ImGui::SetCurrentContext(newContext);
+  ImPlot::SetCurrentContext(newPlotContext);
   ImGui::GetIO().BackendPlatformUserData = nullptr;
   ImGui::GetIO().BackendRendererUserData = nullptr;
 
+  ImPlot::DestroyContext(newPlotContext);
   ImGui::DestroyContext(newContext);
 
   // Restore the previous context, if there was one
   if (!contextStack.empty()) {
     ImGui::SetCurrentContext(contextStack.back().context);
+    ImPlot::SetCurrentContext(contextStack.back().plotContext);
   }
 }
 
diff --git a/src/render/mock_opengl/mock_gl_engine.cpp b/src/render/mock_opengl/mock_gl_engine.cpp
@@ -1576,6 +1576,7 @@ void MockGLEngine::initialize() {
 
 void MockGLEngine::initializeImGui() {
   ImGui::CreateContext(); // must call once at start
+  ImPlot::CreateContext(); 
   configureImGui();
 }
 
@@ -1597,7 +1598,10 @@ void MockGLEngine::shutdown() {
   shutdownImGui();
 }
 
-void MockGLEngine::shutdownImGui() { ImGui::DestroyContext(); }
+void MockGLEngine::shutdownImGui() { 
+  ImPlot::DestroyContext(); 
+  ImGui::DestroyContext(); 
+}
 
 void MockGLEngine::swapDisplayBuffers() {}
 
diff --git a/src/render/opengl/gl_engine_egl.cpp b/src/render/opengl/gl_engine_egl.cpp
@@ -437,6 +437,7 @@ void GLEngineEGL::initializeImGui() {
   // functions
 
   ImGui::CreateContext();
+  ImPlot::CreateContext(); 
   configureImGui();
 }
 
diff --git a/src/render/opengl/gl_engine_glfw.cpp b/src/render/opengl/gl_engine_glfw.cpp
@@ -148,6 +148,7 @@ void GLEngineGLFW::initializeImGui() {
   bindDisplay();
 
   ImGui::CreateContext(); // must call once at start
+  ImPlot::CreateContext(); 
 
   // Set up ImGUI glfw bindings
   ImGui_ImplGlfw_InitForOpenGL(mainWindow, true);
@@ -197,6 +198,7 @@ void GLEngineGLFW::shutdownImGui() {
   // ImGui shutdown things
   ImGui_ImplOpenGL3_Shutdown();
   ImGui_ImplGlfw_Shutdown();
+  ImPlot::DestroyContext();
   ImGui::DestroyContext();
 }
 
diff --git a/src/screenshot.cpp b/src/screenshot.cpp
@@ -47,18 +47,29 @@ std::vector<unsigned char> getRenderInBuffer(const ScreenshotOptions& options =
   bool requestedAlready = redrawRequested();
   requestRedraw();
 
+  // There's a ton of junk needed here to handle the includeUI case...
   // Create a new context and push it on to the stack
+  // FIXME this solution doesn't really work, it forgets UI state like which nodes were open, scrolled setting, etc.
+  // I'm not sure if it's possible to do this like we want in ImGui. The alternate solution would be to save the render
+  // from the previous render pass, but I think that comes with other problems on the Polyscope side. I'm not sure what
+  // the answer is.
   ImGuiContext* oldContext;
   ImGuiContext* newContext;
+  ImPlotContext* oldPlotContext;
+  ImPlotContext* newPlotContext;
   if (options.includeUI) {
     // WARNING: code duplicated here and in pushContext()
     oldContext = ImGui::GetCurrentContext();
     newContext = ImGui::CreateContext();
+    oldPlotContext = ImPlot::GetCurrentContext();
+    newPlotContext = ImPlot::CreateContext();
     ImGuiIO& oldIO = ImGui::GetIO(); // used to GLFW + OpenGL data to the new IO object
 #ifdef IMGUI_HAS_DOCK
     ImGuiPlatformIO& oldPlatformIO = ImGui::GetPlatformIO();
 #endif
     ImGui::SetCurrentContext(newContext);
+    ImPlot::SetCurrentContext(newPlotContext);
+
 #ifdef IMGUI_HAS_DOCK
     // Propagate GLFW window handle to new context
     ImGui::GetMainViewport()->PlatformHandle = oldPlatformIO.Viewports[0]->PlatformHandle;
@@ -81,11 +92,15 @@ std::vector<unsigned char> getRenderInBuffer(const ScreenshotOptions& options =
     // Workaround overzealous ImGui assertion before destroying any inner context
     // https://github.com/ocornut/imgui/pull/7175
     ImGui::SetCurrentContext(newContext);
+    ImPlot::SetCurrentContext(newPlotContext);
     ImGui::GetIO().BackendPlatformUserData = nullptr;
     ImGui::GetIO().BackendRendererUserData = nullptr;
 
+    ImPlot::DestroyContext(newPlotContext);
     ImGui::DestroyContext(newContext);
+
     ImGui::SetCurrentContext(oldContext);
+    ImPlot::SetCurrentContext(oldPlotContext);
   }
 
 
diff --git a/test/src/basics_test.cpp b/test/src/basics_test.cpp
@@ -45,6 +45,7 @@ TEST_F(PolyscopeTest, FrameTickWithImgui) {
   polyscope::state::userCallback = nullptr;
 }
 
+
 // We should be able to nest calls to show() via the callback. ImGUI causes headaches here
 TEST_F(PolyscopeTest, NestedShow) {
 
@@ -148,6 +149,55 @@ TEST_F(PolyscopeTest, ScreenshotBuffer) {
   EXPECT_EQ(buff2.size(), polyscope::view::bufferWidth * polyscope::view::bufferHeight * 4);
 }
 
+TEST_F(PolyscopeTest, ImPlotBasic) {
+
+  std::vector<float> xvals = {0., 2., 4., 8.};
+
+  auto showCallback = [&]() { 
+    ImGui::Button("do something"); 
+    if(ImPlot::BeginPlot("test plot")) {
+      ImPlot::PlotLine("test line", &xvals.front(), xvals.size());
+      ImPlot::EndPlot();
+    }
+  };
+  polyscope::state::userCallback = showCallback;
+
+  polyscope::show(3);
+  
+  for (int i = 0; i < 3; i++) {
+    polyscope::frameTick();
+  }
+
+  polyscope::state::userCallback = nullptr;
+}
+
+
+TEST_F(PolyscopeTest, ImPlotScreenshot) {
+  // test this because there is some context logic duplicated there
+
+  std::vector<float> xvals = {0., 2., 4., 8.};
+
+  auto showCallback = [&]() { 
+    ImGui::Button("do something"); 
+    if(ImPlot::BeginPlot("test plot")) {
+      ImPlot::PlotLine("test line", &xvals.front(), xvals.size());
+      ImPlot::EndPlot();
+    }
+  };
+  polyscope::state::userCallback = showCallback;
+
+  polyscope::show(3);
+  
+  polyscope::ScreenshotOptions opts;
+  opts.includeUI = true;
+  opts.transparentBackground = false;
+  polyscope::screenshot(opts);
+  
+  polyscope::show(3);
+  
+  polyscope::state::userCallback = nullptr;
+}
+
 // ============================================================
 // =============== View and navigation
 // ============================================================

Original file line number	Diff line number	Diff line change
`@@ -1576,6 +1576,7 @@ void MockGLEngine::initialize() {`
`1576`	`1576`
`1577`	`1577`	`void MockGLEngine::initializeImGui() {`
`1578`	`1578`	`ImGui::CreateContext(); // must call once at start`
	`1579`	`+ ImPlot::CreateContext();`
`1579`	`1580`	`configureImGui();`
`1580`	`1581`	`}`
`1581`	`1582`
`@@ -1597,7 +1598,10 @@ void MockGLEngine::shutdown() {`
`1597`	`1598`	`shutdownImGui();`
`1598`	`1599`	`}`
`1599`	`1600`
`1600`		`-void MockGLEngine::shutdownImGui() { ImGui::DestroyContext(); }`
	`1601`	`+void MockGLEngine::shutdownImGui() {`
	`1602`	`+ ImPlot::DestroyContext();`
	`1603`	`+ ImGui::DestroyContext();`
	`1604`	`+}`
`1601`	`1605`
`1602`	`1606`	`void MockGLEngine::swapDisplayBuffers() {}`
`1603`	`1607`
Original file line number	Diff line number	Diff line change
`@@ -437,6 +437,7 @@ void GLEngineEGL::initializeImGui() {`
`437`	`437`	`// functions`
`438`	`438`
`439`	`439`	`ImGui::CreateContext();`
	`440`	`+ ImPlot::CreateContext();`
`440`	`441`	`configureImGui();`
`441`	`442`	`}`
`442`	`443`