HelpersImGui: use the standard ImGui backend for GLFW

corporateshark · corporateshark · commit 333b64bbd17b · 2026-01-17T02:24:01.000-08:00
diff --git a/lvk/HelpersImGui.cpp b/lvk/HelpersImGui.cpp
@@ -1,9 +1,9 @@
 /*
-* LightweightVK
-*
-* This source code is licensed under the MIT license found in the
-* LICENSE file in the root directory of this source tree.
-*/
+ * LightweightVK
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
 
 #include "HelpersImGui.h"
 
@@ -16,6 +16,10 @@
 #include "implot/implot_items.cpp"
 #endif // LVK_WITH_IMPLOT
 
+#if LVK_WITH_GLFW
+#include "imgui/backends/imgui_impl_glfw.cpp"
+#endif // LVK_WITH_GLFW
+
 #include <math.h>
 
 static const char* codeVS = R"(
@@ -105,7 +109,8 @@ lvk::Holder<lvk::RenderPipelineHandle> ImGuiRenderer::createNewPipelineState(con
       nullptr);
 }
 
-ImGuiRenderer::ImGuiRenderer(lvk::IContext& device, const char* defaultFontTTF, float fontSizePixels) : ctx_(device) {
+ImGuiRenderer::ImGuiRenderer(lvk::IContext& device, lvk::LVKwindow* window, const char* defaultFontTTF, float fontSizePixels)
+: ctx_(device) {
   ImGui::CreateContext();
 #if defined(LVK_WITH_IMPLOT)
   ImPlot::CreateContext();
@@ -114,9 +119,15 @@ ImGuiRenderer::ImGuiRenderer(lvk::IContext& device, const char* defaultFontTTF,
   ImGuiIO& io = ImGui::GetIO();
   io.BackendRendererName = "imgui-lvk";
   io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;
+  io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
+  io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;
+
+#if LVK_WITH_GLFW
+  ImGui_ImplGlfw_InitForOther(window, window ? true : false);
+#endif // LVK_WITH_GLFW
 
   updateFont(defaultFontTTF, fontSizePixels);
-  
+
   vert_ = ctx_.createShaderModule({codeVS, Stage_Vert, "Shader Module: imgui (vert)"});
   frag_ = ctx_.createShaderModule({codeFS, Stage_Frag, "Shader Module: imgui (frag)"});
   samplerClamp_ = ctx_.createSampler({
@@ -129,6 +140,9 @@ ImGuiRenderer::ImGuiRenderer(lvk::IContext& device, const char* defaultFontTTF,
 ImGuiRenderer::~ImGuiRenderer() {
   ImGuiIO& io = ImGui::GetIO();
   io.Fonts->TexRef = ImTextureRef();
+#if LVK_WITH_GLFW
+  ImGui_ImplGlfw_Shutdown();
+#endif // LVK_WITH_GLFW
 #if defined(LVK_WITH_IMPLOT)
   ImPlot::DestroyContext();
 #endif // LVK_WITH_IMPLOT
@@ -179,6 +193,9 @@ void ImGuiRenderer::beginFrame(const lvk::Framebuffer& desc) {
   if (pipeline_.empty()) {
     pipeline_ = createNewPipelineState(desc);
   }
+#if LVK_WITH_GLFW
+  ImGui_ImplGlfw_NewFrame();
+#endif // LVK_WITH_GLFW
   ImGui::NewFrame();
 }
 
diff --git a/lvk/HelpersImGui.h b/lvk/HelpersImGui.h
@@ -16,7 +16,7 @@ namespace lvk {
 
 class ImGuiRenderer {
  public:
-  explicit ImGuiRenderer(lvk::IContext& device, const char* defaultFontTTF = nullptr, float fontSizePixels = 24.0f);
+  explicit ImGuiRenderer(lvk::IContext& device, lvk::LVKwindow* window, const char* defaultFontTTF = nullptr, float fontSizePixels = 24.0f);
   ~ImGuiRenderer();
   
   void updateFont(const char* defaultFontTTF, float fontSizePixels);
diff --git a/samples/004_YUV.cpp b/samples/004_YUV.cpp
@@ -127,8 +127,8 @@ void createDemo(const char* name, lvk::Format format, const char* fileName) {
   });
 }
 
-void init() {
-  res_.imgui = std::make_unique<lvk::ImGuiRenderer>(*ctx_, nullptr, float(height_) / 70.0f);
+void init(lvk::LVKwindow* window) {
+  res_.imgui = std::make_unique<lvk::ImGuiRenderer>(*ctx_, window, nullptr, float(height_) / 70.0f);
 
   res_.vert = ctx_->createShaderModule({codeVS, lvk::Stage_Vert, "Shader Module: main (vert)"});
   res_.frag = ctx_->createShaderModule({codeFS, lvk::Stage_Frag, "Shader Module: main (frag)"});
@@ -205,7 +205,7 @@ int main(int argc, char* argv[]) {
   if (!ctx_) {
     return 1;
   }
-  init();
+  init(window);
 
   glfwSetFramebufferSizeCallback(window, [](GLFWwindow*, int width, int height) {
     width_ = width;
diff --git a/samples/007_RayTracingAO.cpp b/samples/007_RayTracingAO.cpp
@@ -466,7 +466,7 @@ bool initModel();
 void createPipelines();
 void createOffscreenFramebuffer();
 
-bool init() {
+bool init(lvk::LVKwindow* window) {
   for (uint32_t i = 0; i != kNumBufferedFrames; i++) {
     ubPerFrame_.push_back(ctx_->createBuffer({.usage = lvk::BufferUsageBits_Uniform,
                                               .storage = lvk::StorageType_HostVisible,
@@ -513,7 +513,7 @@ bool init() {
   createPipelines();
 
   imgui_ = std::make_unique<lvk::ImGuiRenderer>(
-      *ctx_, (folderThirdParty + "3D-Graphics-Rendering-Cookbook/data/OpenSans-Light.ttf").c_str(), float(height_) / 70.0f);
+      *ctx_, window, (folderThirdParty + "3D-Graphics-Rendering-Cookbook/data/OpenSans-Light.ttf").c_str(), float(height_) / 70.0f);
 
   if (!initModel()) {
     return false;
@@ -1123,7 +1123,7 @@ int main(int argc, char* argv[]) {
     return EXIT_FAILURE;
   }
 
-  if (!init()) {
+  if (!init(window)) {
     return EXIT_FAILURE;
   }
 
diff --git a/samples/Tiny_Mesh.cpp b/samples/Tiny_Mesh.cpp
@@ -196,7 +196,7 @@ UniformsPerObject perObject[kNumCubes];
 void initObjects();
 std::filesystem::path getPathToContentFolder();
 
-void init() {
+void init(lvk::LVKwindow* window) {
   // Vertex buffer, Index buffer and Vertex Input. Buffers are allocated in GPU memory.
   vb0_ = ctx_->createBuffer({.usage = lvk::BufferUsageBits_Storage,
                                 .storage = lvk::StorageType_Device,
@@ -296,7 +296,7 @@ void init() {
 
   initObjects();
 
-  imgui_ = std::make_unique<lvk::ImGuiRenderer>(*ctx_);
+  imgui_ = std::make_unique<lvk::ImGuiRenderer>(*ctx_, window);
 }
 
 void destroy() {
@@ -448,7 +448,7 @@ int main(int argc, char* argv[]) {
     return 1;
   }
 
-  init();
+  init(window);
 
   glfwSetCursorPosCallback(window, [](auto* window, double x, double y) { ImGui::GetIO().MousePos = ImVec2(x, y); });
   glfwSetMouseButtonCallback(window, [](auto* window, int button, int action, int mods) {
@@ -515,7 +515,7 @@ void handle_cmd(android_app* app, int32_t cmd) {
       width_ = ANativeWindow_getWidth(app->window);
       height_ = ANativeWindow_getHeight(app->window);
       ctx_ = lvk::createVulkanContextWithSwapchain(app->window, width_, height_, {});
-      init();
+      init(nullptr);
     }
     break;
   case APP_CMD_TERM_WINDOW:
diff --git a/samples/Tiny_MeshLarge.cpp b/samples/Tiny_MeshLarge.cpp
@@ -669,7 +669,7 @@ void createPipelines();
 void createShadowMap();
 void createOffscreenFramebuffer();
 
-bool init() {
+bool init(lvk::LVKwindow* window) {
   {
     const uint32_t pixel = 0xFFFFFFFF;
     textureDummyWhite_ = ctx_->createTexture(
@@ -757,7 +757,7 @@ bool init() {
   createPipelines();
 
   imgui_ = std::make_unique<lvk::ImGuiRenderer>(
-      *ctx_, (folderThirdParty + "3D-Graphics-Rendering-Cookbook/data/OpenSans-Light.ttf").c_str(), float(height_) / 70.0f);
+      *ctx_, window, (folderThirdParty + "3D-Graphics-Rendering-Cookbook/data/OpenSans-Light.ttf").c_str(), float(height_) / 70.0f);
 
   queryPoolTimestamps_ = ctx_->createQueryPool(GPUTimestamp_NUM_TIMESTAMPS, "queryPoolTimestamps_");
 
@@ -2084,6 +2084,7 @@ double getCurrentTimestamp() {
 }
 
 GLFWkeyfun g_PrevKeyCallback = nullptr;
+GLFWmousebuttonfun g_PrevMouseButtonCallback = nullptr;
 
 int main(int argc, char* argv[]) {
   minilog::initialize(nullptr, {.threadNames = false});
@@ -2122,7 +2123,7 @@ int main(int argc, char* argv[]) {
     printf("Compressing textures... It can take a while in debug builds...(needs to be done once)\n");
   }
 
-  if (!init()) {
+  if (!init(window)) {
     return EXIT_FAILURE;
   }
 
@@ -2141,7 +2142,7 @@ int main(int argc, char* argv[]) {
     }
   });
 
-  glfwSetMouseButtonCallback(window, [](auto* window, int button, int action, int mods) {
+  g_PrevMouseButtonCallback = glfwSetMouseButtonCallback(window, [](auto* window, int button, int action, int mods) {
     if (!ImGui::GetIO().WantCaptureMouse) {
       if (button == GLFW_MOUSE_BUTTON_LEFT) {
         mousePressed_ = (action == GLFW_PRESS);
@@ -2150,20 +2151,9 @@ int main(int argc, char* argv[]) {
       // release the mouse
       mousePressed_ = false;
     }
-    double xpos, ypos;
-    glfwGetCursorPos(window, &xpos, &ypos);
-    const ImGuiMouseButton_ imguiButton = (button == GLFW_MOUSE_BUTTON_LEFT)
-                                              ? ImGuiMouseButton_Left
-                                              : (button == GLFW_MOUSE_BUTTON_RIGHT ? ImGuiMouseButton_Right : ImGuiMouseButton_Middle);
-    ImGuiIO& io = ImGui::GetIO();
-    io.MousePos = ImVec2((float)xpos, (float)ypos);
-    io.MouseDown[imguiButton] = action == GLFW_PRESS;
-  });
-
-  glfwSetScrollCallback(window, [](GLFWwindow* window, double dx, double dy) {
-    ImGuiIO& io = ImGui::GetIO();
-    io.MouseWheelH = (float)dx;
-    io.MouseWheel = (float)dy;
+    // call the previous installed callback
+    if (g_PrevMouseButtonCallback)
+      g_PrevMouseButtonCallback(window, button, action, mods);
   });
 
   g_PrevKeyCallback = glfwSetKeyCallback(window, [](GLFWwindow* window, int key, int scancode, int action, int mods) {
@@ -2290,7 +2280,7 @@ void handle_cmd(android_app* app, int32_t cmd) {
                                                    },
                                                    kPreferIntegratedGPU ? lvk::HWDeviceType_Integrated : 
                                                                           lvk::HWDeviceType_Discrete);
-      if (!init()) {
+      if (!init(nullptr)) {
         LLOGW("Failed to initialize the app\n");
         std::terminate();
       }
