Implement ImguiBackend::Render()

Create geometry in Render() before calling Draw()

src/engine/engine.cc

@@ -70,12 +70,9 @@ void Engine::Run() {
   Initialize();
 
   DeltaTimer timer;
-  float accumulator = 0.0;
-  float frame_frac = 0.0f;
+  float accumulator = 0.0f;
 
   for (;;) {
-    TaskRunner::GetThreadLocalTaskRunner()->RunTasks();
-
     platform_->Update();
     if (platform_->should_exit())
       return;
@@ -83,8 +80,6 @@ void Engine::Run() {
     if (!renderer_->IsInitialzed())
       continue;
 
-    Draw(frame_frac);
-
     // Accumulate time.
     accumulator += timer.Delta();
 
@@ -94,8 +89,11 @@ void Engine::Run() {
       accumulator -= time_step_;
     };
 
+    TaskRunner::GetThreadLocalTaskRunner()->RunTasks();
+
     // Calculate frame fraction from remainder of the frame time.
-    frame_frac = accumulator / time_step_;
+    float frame_frac = accumulator / time_step_;
+    Draw(frame_frac);
   }
 }
 
@@ -145,6 +143,8 @@ void Engine::Update(float delta_time) {
 
   if (stats_visible_)
     ShowStats();
+
+  imgui_backend_.Render();
 }
 
 void Engine::Draw(float frame_frac) {

src/engine/imgui_backend.cc

@@ -65,8 +65,6 @@ void ImguiBackend::Initialize() {
   Engine::Get().RefreshImage("imgui_atlas");
   ImGui::GetIO().Fonts->SetTexID(
       (ImTextureID)(intptr_t)Engine::Get().AcquireTexture("imgui_atlas"));
-
-  NewFrame(0);
 }
 
 void ImguiBackend::Shutdown() {
@@ -117,9 +115,9 @@ std::unique_ptr<InputEvent> ImguiBackend::OnInputEvent(
 }
 
 void ImguiBackend::NewFrame(float delta_time) {
-  if (is_new_frame_)
-    ImGui::EndFrame();
-  is_new_frame_ = true;
+  for (auto& id : geometries_)
+    renderer_->DestroyGeometry(id);
+  geometries_.clear();
 
   ImGuiIO& io = ImGui::GetIO();
   io.DisplaySize = ImVec2((float)renderer_->GetScreenWidth(),
@@ -128,13 +126,28 @@ void ImguiBackend::NewFrame(float delta_time) {
   ImGui::NewFrame();
 }
 
-void ImguiBackend::Draw() {
-  is_new_frame_ = false;
+void ImguiBackend::Render() {
   ImGui::Render();
   ImDrawData* draw_data = ImGui::GetDrawData();
-  if (draw_data->CmdListsCount <= 0)
+  geometries_.resize(draw_data->CmdListsCount);
+  for (int n = 0; n < draw_data->CmdListsCount; n++) {
+    const ImDrawList* cmd_list = draw_data->CmdLists[n];
+    auto mesh = std::make_unique<Mesh>();
+    mesh->Create(kPrimitive_Triangles, vertex_description,
+                 cmd_list->VtxBuffer.Size, cmd_list->VtxBuffer.Data,
+                 kDataType_UShort, cmd_list->IdxBuffer.Size,
+                 cmd_list->IdxBuffer.Data);
+    geometries_[n] = renderer_->CreateGeometry(std::move(mesh));
+  }
+}
+
+void ImguiBackend::Draw() {
+  ImDrawData* draw_data = ImGui::GetDrawData();
+  if (!draw_data || draw_data->CmdListsCount <= 0)
     return;
 
+  renderer_->SetViewport(0, 0, draw_data->DisplaySize.x, draw_data->DisplaySize.y);
+
   base::Matrix4f ortho_projection;
   ortho_projection.CreateOrthoProjection(
       draw_data->DisplayPos.x,
@@ -147,28 +160,20 @@ void ImguiBackend::Draw() {
 
   for (int n = 0; n < draw_data->CmdListsCount; n++) {
     const ImDrawList* cmd_list = draw_data->CmdLists[n];
-    auto mesh = std::make_unique<Mesh>();
-    mesh->Create(kPrimitive_Triangles, vertex_description,
-                 cmd_list->VtxBuffer.Size, cmd_list->VtxBuffer.Data,
-                 kDataType_UShort, cmd_list->IdxBuffer.Size,
-                 cmd_list->IdxBuffer.Data);
-    auto geometry_id = renderer_->CreateGeometry(std::move(mesh));
-
     for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++) {
       const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
       if (pcmd->ClipRect.z <= pcmd->ClipRect.x ||
           pcmd->ClipRect.w <= pcmd->ClipRect.y)
         continue;
-
       reinterpret_cast<Texture*>(pcmd->GetTexID())->Activate(0);
       renderer_->SetScissor(int(pcmd->ClipRect.x), int(pcmd->ClipRect.y),
                             int(pcmd->ClipRect.z - pcmd->ClipRect.x),
                             int(pcmd->ClipRect.w - pcmd->ClipRect.y));
-      renderer_->Draw(geometry_id, pcmd->ElemCount, pcmd->IdxOffset);
+      renderer_->Draw(geometries_[n], pcmd->ElemCount, pcmd->IdxOffset);
     }
-    renderer_->DestroyGeometry(geometry_id);
   }
   renderer_->ResetScissor();
+  renderer_->ResetViewport();
 }
 
 }  // namespace eng

src/engine/imgui_backend.h

@@ -2,6 +2,7 @@
 #define ENGINE_IMGUI_BACKEND_H
 
 #include <memory>
+#include <vector>
 
 namespace eng {
 
@@ -22,12 +23,13 @@ class ImguiBackend {
   std::unique_ptr<InputEvent> OnInputEvent(std::unique_ptr<InputEvent> event);
 
   void NewFrame(float delta_time);
+  void Render();
   void Draw();
 
  private:
+  std::vector<uint64_t> geometries_;
   std::unique_ptr<Shader> shader_;
   Renderer* renderer_ = nullptr;
-  bool is_new_frame_ = false;
 };
 
 }  // namespace eng

src/engine/renderer/opengl/renderer_opengl.cc

@@ -47,7 +47,6 @@ RendererOpenGL::~RendererOpenGL() {
 void RendererOpenGL::OnWindowResized(int width, int height) {
   screen_width_ = width;
   screen_height_ = height;
-  glViewport(0, 0, screen_width_, screen_height_);
 }
 
 int RendererOpenGL::GetScreenWidth() const {
@@ -58,6 +57,14 @@ int RendererOpenGL::GetScreenHeight() const {
   return screen_height_;
 }
 
+void RendererOpenGL::SetViewport(int x, int y, int width, int height) {
+  glViewport(0, 0, width, height);
+}
+
+void RendererOpenGL::ResetViewport() {
+  glViewport(0, 0, screen_width_, screen_height_);
+}
+
 void RendererOpenGL::SetScissor(int x, int y, int width, int height) {
   glScissor(x, screen_height_ - y - height, width, height);
   glEnable(GL_SCISSOR_TEST);
@@ -436,6 +443,7 @@ void RendererOpenGL::SetUniform(uint64_t resource_id,
 }
 
 void RendererOpenGL::PrepareForDrawing() {
+  glViewport(0, 0, screen_width_, screen_height_);
   glDisable(GL_SCISSOR_TEST);
 }
 

src/engine/renderer/opengl/renderer_opengl.h

@@ -32,6 +32,9 @@ class RendererOpenGL final : public Renderer {
   int GetScreenWidth() const final;
   int GetScreenHeight() const final;
 
+  void SetViewport(int x, int y, int width, int height) final;
+  void ResetViewport() final;
+
   void SetScissor(int x, int y, int width, int height) final;
   void ResetScissor() final;
 

src/engine/renderer/renderer.h

@@ -39,6 +39,9 @@ class Renderer {
   virtual int GetScreenWidth() const = 0;
   virtual int GetScreenHeight() const = 0;
 
+  virtual void SetViewport(int x, int y, int width, int height) = 0;
+  virtual void ResetViewport() = 0;
+
   virtual void SetScissor(int x, int y, int width, int height) = 0;
   virtual void ResetScissor() = 0;
 

src/engine/renderer/vulkan/renderer_vulkan.cc

@@ -390,6 +390,30 @@ int RendererVulkan::GetScreenHeight() const {
   return context_.GetWindowHeight();
 }
 
+void RendererVulkan::SetViewport(int x, int y, int width, int height) {
+  VkViewport viewport;
+  viewport.x = 0;
+  viewport.y = (float)height;
+  viewport.width = (float)width;
+  viewport.height = -(float)height;
+  viewport.minDepth = 0;
+  viewport.maxDepth = 1.0;
+  vkCmdSetViewport(frames_[current_frame_].draw_command_buffer, 0, 1,
+                   &viewport);
+}
+
+void RendererVulkan::ResetViewport() {
+  VkViewport viewport;
+  viewport.x = 0;
+  viewport.y = (float)context_.GetWindowHeight();
+  viewport.width = (float)context_.GetWindowWidth();
+  viewport.height = -(float)context_.GetWindowHeight();
+  viewport.minDepth = 0;
+  viewport.maxDepth = 1.0;
+  vkCmdSetViewport(frames_[current_frame_].draw_command_buffer, 0, 1,
+                   &viewport);
+}
+
 void RendererVulkan::SetScissor(int x, int y, int width, int height) {
   if (x < 0)
     x = 0;
@@ -1990,8 +2014,6 @@ bool RendererVulkan::CreatePipelineLayout(
 }
 
 void RendererVulkan::DrawListBegin() {
-  VkCommandBuffer command_buffer = frames_[current_frame_].draw_command_buffer;
-
   VkRenderPassBeginInfo render_pass_begin;
   render_pass_begin.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
   render_pass_begin.pNext = nullptr;
@@ -2010,26 +2032,11 @@ void RendererVulkan::DrawListBegin() {
   render_pass_begin.clearValueCount = clear_values.size();
   render_pass_begin.pClearValues = clear_values.data();
 
-  vkCmdBeginRenderPass(command_buffer, &render_pass_begin,
-                       VK_SUBPASS_CONTENTS_INLINE);
+  vkCmdBeginRenderPass(frames_[current_frame_].draw_command_buffer,
+                       &render_pass_begin, VK_SUBPASS_CONTENTS_INLINE);
 
-  VkViewport viewport;
-  viewport.x = 0;
-  viewport.y = (float)context_.GetWindowHeight();
-  viewport.width = (float)context_.GetWindowWidth();
-  viewport.height = -(float)context_.GetWindowHeight();
-  viewport.minDepth = 0;
-  viewport.maxDepth = 1.0;
-
-  vkCmdSetViewport(command_buffer, 0, 1, &viewport);
-
-  VkRect2D scissor;
-  scissor.offset.x = 0;
-  scissor.offset.y = 0;
-  scissor.extent.width = context_.GetWindowWidth();
-  scissor.extent.height = context_.GetWindowHeight();
-
-  vkCmdSetScissor(command_buffer, 0, 1, &scissor);
+  ResetViewport();
+  ResetScissor();
 }
 
 void RendererVulkan::DrawListEnd() {

src/engine/renderer/vulkan/renderer_vulkan.h

@@ -33,6 +33,9 @@ class RendererVulkan final : public Renderer {
   int GetScreenWidth() const final;
   int GetScreenHeight() const final;
 
+  void SetViewport(int x, int y, int width, int height) final;
+  void ResetViewport() final;
+
   void SetScissor(int x, int y, int width, int height) final;
   void ResetScissor() final;