Activate imgui shader only once.

src/engine/imgui_backend.cc

@@ -15,6 +15,10 @@ using namespace base;
 
 namespace eng {
 
+namespace {
+const char vertex_description[] = "p2f;t2f;c4b";
+}  // namespace
+
 ImguiBackend::ImguiBackend() : shader_{std::make_unique<Shader>(nullptr)} {}
 
 ImguiBackend::~ImguiBackend() = default;
@@ -54,7 +58,6 @@ void ImguiBackend::CreateRenderResources(Renderer* renderer) {
 
   auto source = std::make_unique<ShaderSource>();
   if (source->Load("engine/imgui.glsl")) {
-    static const char vertex_description[] = "p2f;t2f;c4b";
     VertexDescription vd;
     if (!ParseVertexDescription(vertex_description, vd)) {
       DLOG(0) << "Failed to parse vertex description.";
@@ -113,9 +116,12 @@ void ImguiBackend::Render() {
   base::Matrix4f ortho_projection;
   ortho_projection.CreateOrthoProjection(L, R, B, T);
 
+  shader_->Activate();
+  shader_->SetUniform("projection", ortho_projection);
+  shader_->UploadUniforms();
+
   for (int n = 0; n < draw_data->CmdListsCount; n++) {
     const ImDrawList* cmd_list = draw_data->CmdLists[n];
-    static const char vertex_description[] = "p2f;t2f;c4b";
     auto mesh = std::make_unique<Mesh>();
     mesh->Create(kPrimitive_Triangles, vertex_description,
                  cmd_list->VtxBuffer.Size, cmd_list->VtxBuffer.Data,
@@ -127,12 +133,6 @@ void ImguiBackend::Render() {
       const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
       reinterpret_cast<Texture*>(pcmd->GetTexID())->Activate();
 
-      // Vulkan renderer needs activating the shader again after a texture.
-      // TODO: Fix it in vulkan renderer and active the shader only once.
-      shader_->Activate();
-      shader_->SetUniform("projection", ortho_projection);
-      shader_->UploadUniforms();
-
       if (pcmd->ClipRect.z > pcmd->ClipRect.x &&
           pcmd->ClipRect.w > pcmd->ClipRect.y) {
         renderer_->SetScissor(int(pcmd->ClipRect.x), int(pcmd->ClipRect.y),

src/engine/renderer/vulkan/renderer_vulkan.cc

@@ -564,8 +564,19 @@ void RendererVulkan::ActivateTexture(uint64_t resource_id) {
   if (it == textures_.end())
     return;
 
-  // Keep as pending and bind later in ActivateShader.
-  pending_descriptor_sets_[/*TODO*/ 0] = std::get<0>(it->second.desc_set);
+  if (active_descriptor_sets_[/*TODO*/ 0] != std::get<0>(it->second.desc_set)) {
+    active_descriptor_sets_[/*TODO*/ 0] = std::get<0>(it->second.desc_set);
+    if (active_shader_id_ != 0) {
+      auto active_shader = shaders_.find(active_shader_id_);
+      if (active_shader != shaders_.end() &&
+          active_shader->second.desc_set_count > 0) {
+        vkCmdBindDescriptorSets(frames_[current_frame_].draw_command_buffer,
+                                VK_PIPELINE_BIND_POINT_GRAPHICS,
+                                active_shader->second.pipeline_layout, 0, 1,
+                                &active_descriptor_sets_[0], 0, nullptr);
+      }
+    }
+  }
 }
 
 uint64_t RendererVulkan::CreateShader(
@@ -773,19 +784,16 @@ void RendererVulkan::ActivateShader(uint64_t resource_id) {
   if (it == shaders_.end())
     return;
 
-  if (active_pipeline_ != it->second.pipeline) {
-    active_pipeline_ = it->second.pipeline;
+  if (active_shader_id_ != resource_id) {
+    active_shader_id_ = resource_id;
     vkCmdBindPipeline(frames_[current_frame_].draw_command_buffer,
                       VK_PIPELINE_BIND_POINT_GRAPHICS, it->second.pipeline);
-  }
-  for (size_t i = 0; i < it->second.desc_set_count; ++i) {
-    if (active_descriptor_sets_[i] != pending_descriptor_sets_[i]) {
-      active_descriptor_sets_[i] = pending_descriptor_sets_[i];
+    if (it->second.desc_set_count > 0 &&
+        active_descriptor_sets_[/*TODO*/ 0] != VK_NULL_HANDLE) {
       vkCmdBindDescriptorSets(frames_[current_frame_].draw_command_buffer,
                               VK_PIPELINE_BIND_POINT_GRAPHICS,
                               it->second.pipeline_layout, 0, 1,
-                              &active_descriptor_sets_[i], 0, nullptr);
-      break;
+                              &active_descriptor_sets_[0], 0, nullptr);
     }
   }
 }
@@ -1832,10 +1840,8 @@ bool RendererVulkan::CreatePipelineLayout(
       }
     }
 
-    if (active_descriptor_sets_.size() < shader.desc_set_count) {
+    if (active_descriptor_sets_.size() < shader.desc_set_count)
       active_descriptor_sets_.resize(shader.desc_set_count);
-      pending_descriptor_sets_.resize(shader.desc_set_count);
-    }
 
     // Parse push constants.
     auto enumerate_pc = [&](SpvReflectShaderModule& module, uint32_t& pc_count,
@@ -2047,11 +2053,9 @@ void RendererVulkan::SwapBuffers() {
   context_.SwapBuffers();
   current_frame_ = (current_frame_ + 1) % frames_.size();
 
-  active_pipeline_ = VK_NULL_HANDLE;
+  active_shader_id_ = 0;
   for (auto& ds : active_descriptor_sets_)
     ds = VK_NULL_HANDLE;
-  for (auto& ds : pending_descriptor_sets_)
-    ds = VK_NULL_HANDLE;
 
   BeginFrame();
 }

src/engine/renderer/vulkan/renderer_vulkan.h

@@ -179,12 +179,11 @@ class RendererVulkan final : public Renderer {
   uint64_t max_staging_buffer_size_ = 16 * 1024 * 1024;
   bool staging_buffer_used_ = false;
 
-  VkPipeline active_pipeline_ = VK_NULL_HANDLE;
+  uint64_t active_shader_id_ = 0;
 
   std::vector<std::unique_ptr<DescPool>> desc_pools_;
   VkDescriptorSetLayout descriptor_set_layout_ = VK_NULL_HANDLE;
   std::vector<VkDescriptorSet> active_descriptor_sets_;
-  std::vector<VkDescriptorSet> pending_descriptor_sets_;
 
   VkSampler sampler_ = VK_NULL_HANDLE;