Fix build errors and update all dependencies to latest version

- Fixed doctest executable not compiling
- Fixed class accessibility error in Workflow_Main.cpp
- Fixed selection of OpenGL loader in imgui OpenGL 2 & 3 backends
  - All loading is handled in our code now, the imgui_*_backend.cpp files are instructed to do nothing

1 files changed, 251 insertions, 161 deletions

diff --git a/3rdparty/imgui/backend/imgui_impl_vulkan.cpp b/3rdparty/imgui/backend/imgui_impl_vulkan.cpp
index 167687e..dbd8b18 100644
--- a/3rdparty/imgui/backend/imgui_impl_vulkan.cpp
+++ b/3rdparty/imgui/backend/imgui_impl_vulkan.cpp
@@ -3,10 +3,18 @@
 
 // Implemented features:
 //  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
-// Missing features:
-//  [ ] Renderer: User texture binding. Changes of ImTextureID aren't supported by this backend! See https://github.com/ocornut/imgui/pull/914
+//  [!] Renderer: User texture binding. Use 'VkDescriptorSet' as ImTextureID. Read the FAQ about ImTextureID! See https://github.com/ocornut/imgui/pull/914 for discussions.
 
-// You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
+// Important: on 32-bit systems, user texture binding is only supported if your imconfig file has '#define ImTextureID ImU64'.
+// This is because we need ImTextureID to carry a 64-bit value and by default ImTextureID is defined as void*.
+// To build this on 32-bit systems and support texture changes:
+// - [Solution 1] IDE/msbuild: in "Properties/C++/Preprocessor Definitions" add 'ImTextureID=ImU64' (this is what we do in our .vcxproj files)
+// - [Solution 2] IDE/msbuild: in "Properties/C++/Preprocessor Definitions" add 'IMGUI_USER_CONFIG="my_imgui_config.h"' and inside 'my_imgui_config.h' add '#define ImTextureID ImU64' and as many other options as you like.
+// - [Solution 3] IDE/msbuild: edit imconfig.h and add '#define ImTextureID ImU64' (prefer solution 2 to create your own config file!)
+// - [Solution 4] command-line: add '/D ImTextureID=ImU64' to your cl.exe command-line (this is what we do in our batch files)
+
+// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
+// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
 // Read online: https://github.com/ocornut/imgui/tree/master/docs
 
@@ -22,6 +30,8 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2021-10-15: Vulkan: Call vkCmdSetScissor() at the end of render a full-viewport to reduce likehood of issues with people using VK_DYNAMIC_STATE_SCISSOR in their app without calling vkCmdSetScissor() explicitly every frame.
+//  2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX).
 //  2021-03-22: Vulkan: Fix mapped memory validation error when buffer sizes are not multiple of VkPhysicalDeviceLimits::nonCoherentAtomSize.
 //  2021-02-18: Vulkan: Change blending equation to preserve alpha in output buffer.
 //  2021-01-27: Vulkan: Added support for custom function load and IMGUI_IMPL_VULKAN_NO_PROTOTYPES by using ImGui_ImplVulkan_LoadFunctions().
@@ -54,6 +64,11 @@
 #include "imgui_impl_vulkan.h"
 #include <stdio.h>
 
+// Visual Studio warnings
+#ifdef _MSC_VER
+#pragma warning (disable: 4127) // condition expression is constant
+#endif
+
 // Reusable buffers used for rendering 1 current in-flight frame, for ImGui_ImplVulkan_RenderDrawData()
 // [Please zero-clear before use!]
 struct ImGui_ImplVulkanH_FrameRenderBuffers
@@ -76,33 +91,37 @@ struct ImGui_ImplVulkanH_WindowRenderBuffers
 };
 
 // Vulkan data
-static ImGui_ImplVulkan_InitInfo g_VulkanInitInfo = {};
-static VkRenderPass             g_RenderPass = VK_NULL_HANDLE;
-static VkDeviceSize             g_BufferMemoryAlignment = 256;
-static VkPipelineCreateFlags    g_PipelineCreateFlags = 0x00;
-static VkDescriptorSetLayout    g_DescriptorSetLayout = VK_NULL_HANDLE;
-static VkPipelineLayout         g_PipelineLayout = VK_NULL_HANDLE;
-static VkDescriptorSet          g_DescriptorSet = VK_NULL_HANDLE;
-static VkPipeline               g_Pipeline = VK_NULL_HANDLE;
-static uint32_t                 g_Subpass = 0;
-static VkShaderModule           g_ShaderModuleVert;
-static VkShaderModule           g_ShaderModuleFrag;
-#ifdef VK_NO_PROTOTYPES
-static bool                     g_FunctionsLoaded = false;
-#else
-static bool                     g_FunctionsLoaded = true;
-#endif
+struct ImGui_ImplVulkan_Data
+{
+    ImGui_ImplVulkan_InitInfo   VulkanInitInfo;
+    VkRenderPass                RenderPass;
+    VkDeviceSize                BufferMemoryAlignment;
+    VkPipelineCreateFlags       PipelineCreateFlags;
+    VkDescriptorSetLayout       DescriptorSetLayout;
+    VkPipelineLayout            PipelineLayout;
+    VkPipeline                  Pipeline;
+    uint32_t                    Subpass;
+    VkShaderModule              ShaderModuleVert;
+    VkShaderModule              ShaderModuleFrag;
 
-// Font data
-static VkSampler                g_FontSampler = VK_NULL_HANDLE;
-static VkDeviceMemory           g_FontMemory = VK_NULL_HANDLE;
-static VkImage                  g_FontImage = VK_NULL_HANDLE;
-static VkImageView              g_FontView = VK_NULL_HANDLE;
-static VkDeviceMemory           g_UploadBufferMemory = VK_NULL_HANDLE;
-static VkBuffer                 g_UploadBuffer = VK_NULL_HANDLE;
+    // Font data
+    VkSampler                   FontSampler;
+    VkDeviceMemory              FontMemory;
+    VkImage                     FontImage;
+    VkImageView                 FontView;
+    VkDescriptorSet             FontDescriptorSet;
+    VkDeviceMemory              UploadBufferMemory;
+    VkBuffer                    UploadBuffer;
 
-// Render buffers
-static ImGui_ImplVulkanH_WindowRenderBuffers    g_MainWindowRenderBuffers;
+    // Render buffers
+    ImGui_ImplVulkanH_WindowRenderBuffers MainWindowRenderBuffers;
+
+    ImGui_ImplVulkan_Data()
+    {
+        memset(this, 0, sizeof(*this));
+        BufferMemoryAlignment = 256;
+    }
+};
 
 // Forward Declarations
 bool ImGui_ImplVulkan_CreateDeviceObjects();
@@ -117,6 +136,11 @@ void ImGui_ImplVulkanH_CreateWindowCommandBuffers(VkPhysicalDevice physical_devi
 // Vulkan prototypes for use with custom loaders
 // (see description of IMGUI_IMPL_VULKAN_NO_PROTOTYPES in imgui_impl_vulkan.h
 #ifdef VK_NO_PROTOTYPES
+static bool g_FunctionsLoaded = false;
+#else
+static bool g_FunctionsLoaded = true;
+#endif
+#ifdef VK_NO_PROTOTYPES
 #define IMGUI_VULKAN_FUNC_MAP(IMGUI_VULKAN_FUNC_MAP_MACRO) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkAllocateCommandBuffers) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkAllocateDescriptorSets) \
@@ -296,9 +320,18 @@ static uint32_t __glsl_shader_frag_spv[] =
 // FUNCTIONS
 //-----------------------------------------------------------------------------
 
+// Backend data stored in io.BackendRendererUserData to allow support for multiple Dear ImGui contexts
+// It is STRONGLY preferred that you use docking branch with multi-viewports (== single Dear ImGui context + multiple windows) instead of multiple Dear ImGui contexts.
+// FIXME: multi-context support is not tested and probably dysfunctional in this backend.
+static ImGui_ImplVulkan_Data* ImGui_ImplVulkan_GetBackendData()
+{
+    return ImGui::GetCurrentContext() ? (ImGui_ImplVulkan_Data*)ImGui::GetIO().BackendRendererUserData : NULL;
+}
+
 static uint32_t ImGui_ImplVulkan_MemoryType(VkMemoryPropertyFlags properties, uint32_t type_bits)
 {
-    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
     VkPhysicalDeviceMemoryProperties prop;
     vkGetPhysicalDeviceMemoryProperties(v->PhysicalDevice, &prop);
     for (uint32_t i = 0; i < prop.memoryTypeCount; i++)
@@ -309,21 +342,25 @@ static uint32_t ImGui_ImplVulkan_MemoryType(VkMemoryPropertyFlags properties, ui
 
 static void check_vk_result(VkResult err)
 {
-    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    if (!bd)
+        return;
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
     if (v->CheckVkResultFn)
         v->CheckVkResultFn(err);
 }
 
 static void CreateOrResizeBuffer(VkBuffer& buffer, VkDeviceMemory& buffer_memory, VkDeviceSize& p_buffer_size, size_t new_size, VkBufferUsageFlagBits usage)
 {
-    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
     VkResult err;
     if (buffer != VK_NULL_HANDLE)
         vkDestroyBuffer(v->Device, buffer, v->Allocator);
     if (buffer_memory != VK_NULL_HANDLE)
         vkFreeMemory(v->Device, buffer_memory, v->Allocator);
 
-    VkDeviceSize vertex_buffer_size_aligned = ((new_size - 1) / g_BufferMemoryAlignment + 1) * g_BufferMemoryAlignment;
+    VkDeviceSize vertex_buffer_size_aligned = ((new_size - 1) / bd->BufferMemoryAlignment + 1) * bd->BufferMemoryAlignment;
     VkBufferCreateInfo buffer_info = {};
     buffer_info.sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;
     buffer_info.size = vertex_buffer_size_aligned;
@@ -334,7 +371,7 @@ static void CreateOrResizeBuffer(VkBuffer& buffer, VkDeviceMemory& buffer_memory
 
     VkMemoryRequirements req;
     vkGetBufferMemoryRequirements(v->Device, buffer, &req);
-    g_BufferMemoryAlignment = (g_BufferMemoryAlignment > req.alignment) ? g_BufferMemoryAlignment : req.alignment;
+    bd->BufferMemoryAlignment = (bd->BufferMemoryAlignment > req.alignment) ? bd->BufferMemoryAlignment : req.alignment;
     VkMemoryAllocateInfo alloc_info = {};
     alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
     alloc_info.allocationSize = req.size;
@@ -349,11 +386,11 @@ static void CreateOrResizeBuffer(VkBuffer& buffer, VkDeviceMemory& buffer_memory
 
 static void ImGui_ImplVulkan_SetupRenderState(ImDrawData* draw_data, VkPipeline pipeline, VkCommandBuffer command_buffer, ImGui_ImplVulkanH_FrameRenderBuffers* rb, int fb_width, int fb_height)
 {
-    // Bind pipeline and descriptor sets:
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+
+    // Bind pipeline:
     {
         vkCmdBindPipeline(command_buffer, VK_PIPELINE_BIND_POINT_GRAPHICS, pipeline);
-        VkDescriptorSet desc_set[1] = { g_DescriptorSet };
-        vkCmdBindDescriptorSets(command_buffer, VK_PIPELINE_BIND_POINT_GRAPHICS, g_PipelineLayout, 0, 1, desc_set, 0, NULL);
     }
 
     // Bind Vertex And Index Buffer:
@@ -386,8 +423,8 @@ static void ImGui_ImplVulkan_SetupRenderState(ImDrawData* draw_data, VkPipeline
         float translate[2];
         translate[0] = -1.0f - draw_data->DisplayPos.x * scale[0];
         translate[1] = -1.0f - draw_data->DisplayPos.y * scale[1];
-        vkCmdPushConstants(command_buffer, g_PipelineLayout, VK_SHADER_STAGE_VERTEX_BIT, sizeof(float) * 0, sizeof(float) * 2, scale);
-        vkCmdPushConstants(command_buffer, g_PipelineLayout, VK_SHADER_STAGE_VERTEX_BIT, sizeof(float) * 2, sizeof(float) * 2, translate);
+        vkCmdPushConstants(command_buffer, bd->PipelineLayout, VK_SHADER_STAGE_VERTEX_BIT, sizeof(float) * 0, sizeof(float) * 2, scale);
+        vkCmdPushConstants(command_buffer, bd->PipelineLayout, VK_SHADER_STAGE_VERTEX_BIT, sizeof(float) * 2, sizeof(float) * 2, translate);
     }
 }
 
@@ -400,12 +437,13 @@ void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer comm
     if (fb_width <= 0 || fb_height <= 0)
         return;
 
-    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
     if (pipeline == VK_NULL_HANDLE)
-        pipeline = g_Pipeline;
+        pipeline = bd->Pipeline;
 
     // Allocate array to store enough vertex/index buffers
-    ImGui_ImplVulkanH_WindowRenderBuffers* wrb = &g_MainWindowRenderBuffers;
+    ImGui_ImplVulkanH_WindowRenderBuffers* wrb = &bd->MainWindowRenderBuffers;
     if (wrb->FrameRenderBuffers == NULL)
     {
         wrb->Index = 0;
@@ -484,42 +522,59 @@ void ImGui_ImplVulkan_RenderDrawData(ImDrawData* draw_data, VkCommandBuffer comm
             else
             {
                 // Project scissor/clipping rectangles into framebuffer space
-                ImVec4 clip_rect;
-                clip_rect.x = (pcmd->ClipRect.x - clip_off.x) * clip_scale.x;
-                clip_rect.y = (pcmd->ClipRect.y - clip_off.y) * clip_scale.y;
-                clip_rect.z = (pcmd->ClipRect.z - clip_off.x) * clip_scale.x;
-                clip_rect.w = (pcmd->ClipRect.w - clip_off.y) * clip_scale.y;
+                ImVec2 clip_min((pcmd->ClipRect.x - clip_off.x) * clip_scale.x, (pcmd->ClipRect.y - clip_off.y) * clip_scale.y);
+                ImVec2 clip_max((pcmd->ClipRect.z - clip_off.x) * clip_scale.x, (pcmd->ClipRect.w - clip_off.y) * clip_scale.y);
 
-                if (clip_rect.x < fb_width && clip_rect.y < fb_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f)
-                {
-                    // Negative offsets are illegal for vkCmdSetScissor
-                    if (clip_rect.x < 0.0f)
-                        clip_rect.x = 0.0f;
-                    if (clip_rect.y < 0.0f)
-                        clip_rect.y = 0.0f;
+                // Clamp to viewport as vkCmdSetScissor() won't accept values that are off bounds
+                if (clip_min.x < 0.0f) { clip_min.x = 0.0f; }
+                if (clip_min.y < 0.0f) { clip_min.y = 0.0f; }
+                if (clip_max.x > fb_width) { clip_max.x = (float)fb_width; }
+                if (clip_max.y > fb_height) { clip_max.y = (float)fb_height; }
+                if (clip_max.x <= clip_min.x || clip_max.y <= clip_min.y)
+                    continue;
 
-                    // Apply scissor/clipping rectangle
-                    VkRect2D scissor;
-                    scissor.offset.x = (int32_t)(clip_rect.x);
-                    scissor.offset.y = (int32_t)(clip_rect.y);
-                    scissor.extent.width = (uint32_t)(clip_rect.z - clip_rect.x);
-                    scissor.extent.height = (uint32_t)(clip_rect.w - clip_rect.y);
-                    vkCmdSetScissor(command_buffer, 0, 1, &scissor);
+                // Apply scissor/clipping rectangle
+                VkRect2D scissor;
+                scissor.offset.x = (int32_t)(clip_min.x);
+                scissor.offset.y = (int32_t)(clip_min.y);
+                scissor.extent.width = (uint32_t)(clip_max.x - clip_min.x);
+                scissor.extent.height = (uint32_t)(clip_max.y - clip_min.y);
+                vkCmdSetScissor(command_buffer, 0, 1, &scissor);
 
-                    // Draw
-                    vkCmdDrawIndexed(command_buffer, pcmd->ElemCount, 1, pcmd->IdxOffset + global_idx_offset, pcmd->VtxOffset + global_vtx_offset, 0);
+                // Bind DescriptorSet with font or user texture
+                VkDescriptorSet desc_set[1] = { (VkDescriptorSet)pcmd->TextureId };
+                if (sizeof(ImTextureID) < sizeof(ImU64))
+                {
+                    // We don't support texture switches if ImTextureID hasn't been redefined to be 64-bit. Do a flaky check that other textures haven't been used.
+                    IM_ASSERT(pcmd->TextureId == (ImTextureID)bd->FontDescriptorSet);
+                    desc_set[0] = bd->FontDescriptorSet;
                 }
+                vkCmdBindDescriptorSets(command_buffer, VK_PIPELINE_BIND_POINT_GRAPHICS, bd->PipelineLayout, 0, 1, desc_set, 0, NULL);
+
+                // Draw
+                vkCmdDrawIndexed(command_buffer, pcmd->ElemCount, 1, pcmd->IdxOffset + global_idx_offset, pcmd->VtxOffset + global_vtx_offset, 0);
             }
         }
         global_idx_offset += cmd_list->IdxBuffer.Size;
         global_vtx_offset += cmd_list->VtxBuffer.Size;
     }
+
+    // Note: at this point both vkCmdSetViewport() and vkCmdSetScissor() have been called.
+    // Our last values will leak into user/application rendering IF:
+    // - Your app uses a pipeline with VK_DYNAMIC_STATE_VIEWPORT or VK_DYNAMIC_STATE_SCISSOR dynamic state
+    // - And you forgot to call vkCmdSetViewport() and vkCmdSetScissor() yourself to explicitely set that state.
+    // If you use VK_DYNAMIC_STATE_VIEWPORT or VK_DYNAMIC_STATE_SCISSOR you are responsible for setting the values before rendering.
+    // In theory we should aim to backup/restore those values but I am not sure this is possible.
+    // We perform a call to vkCmdSetScissor() to set back a full viewport which is likely to fix things for 99% users but technically this is not perfect. (See github #4644)
+    VkRect2D scissor = { { 0, 0 }, { (uint32_t)fb_width, (uint32_t)fb_height } };
+    vkCmdSetScissor(command_buffer, 0, 1, &scissor);
 }
 
 bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
 {
-    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
     ImGuiIO& io = ImGui::GetIO();
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
 
     unsigned char* pixels;
     int width, height;
@@ -544,17 +599,17 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
         info.usage = VK_IMAGE_USAGE_SAMPLED_BIT | VK_IMAGE_USAGE_TRANSFER_DST_BIT;
         info.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
         info.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
-        err = vkCreateImage(v->Device, &info, v->Allocator, &g_FontImage);
+        err = vkCreateImage(v->Device, &info, v->Allocator, &bd->FontImage);
         check_vk_result(err);
         VkMemoryRequirements req;
-        vkGetImageMemoryRequirements(v->Device, g_FontImage, &req);
+        vkGetImageMemoryRequirements(v->Device, bd->FontImage, &req);
         VkMemoryAllocateInfo alloc_info = {};
         alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
         alloc_info.allocationSize = req.size;
         alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, req.memoryTypeBits);
-        err = vkAllocateMemory(v->Device, &alloc_info, v->Allocator, &g_FontMemory);
+        err = vkAllocateMemory(v->Device, &alloc_info, v->Allocator, &bd->FontMemory);
         check_vk_result(err);
-        err = vkBindImageMemory(v->Device, g_FontImage, g_FontMemory, 0);
+        err = vkBindImageMemory(v->Device, bd->FontImage, bd->FontMemory, 0);
         check_vk_result(err);
     }
 
@@ -562,30 +617,18 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
     {
         VkImageViewCreateInfo info = {};
         info.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
-        info.image = g_FontImage;
+        info.image = bd->FontImage;
         info.viewType = VK_IMAGE_VIEW_TYPE_2D;
         info.format = VK_FORMAT_R8G8B8A8_UNORM;
         info.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
         info.subresourceRange.levelCount = 1;
         info.subresourceRange.layerCount = 1;
-        err = vkCreateImageView(v->Device, &info, v->Allocator, &g_FontView);
+        err = vkCreateImageView(v->Device, &info, v->Allocator, &bd->FontView);
         check_vk_result(err);
     }
 
-    // Update the Descriptor Set:
-    {
-        VkDescriptorImageInfo desc_image[1] = {};
-        desc_image[0].sampler = g_FontSampler;
-        desc_image[0].imageView = g_FontView;
-        desc_image[0].imageLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
-        VkWriteDescriptorSet write_desc[1] = {};
-        write_desc[0].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
-        write_desc[0].dstSet = g_DescriptorSet;
-        write_desc[0].descriptorCount = 1;
-        write_desc[0].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
-        write_desc[0].pImageInfo = desc_image;
-        vkUpdateDescriptorSets(v->Device, 1, write_desc, 0, NULL);
-    }
+    // Create the Descriptor Set:
+    bd->FontDescriptorSet = (VkDescriptorSet)ImGui_ImplVulkan_AddTexture(bd->FontSampler, bd->FontView, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL);
 
     // Create the Upload Buffer:
     {
@@ -594,34 +637,34 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
         buffer_info.size = upload_size;
         buffer_info.usage = VK_BUFFER_USAGE_TRANSFER_SRC_BIT;
         buffer_info.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
-        err = vkCreateBuffer(v->Device, &buffer_info, v->Allocator, &g_UploadBuffer);
+        err = vkCreateBuffer(v->Device, &buffer_info, v->Allocator, &bd->UploadBuffer);
         check_vk_result(err);
         VkMemoryRequirements req;
-        vkGetBufferMemoryRequirements(v->Device, g_UploadBuffer, &req);
-        g_BufferMemoryAlignment = (g_BufferMemoryAlignment > req.alignment) ? g_BufferMemoryAlignment : req.alignment;
+        vkGetBufferMemoryRequirements(v->Device, bd->UploadBuffer, &req);
+        bd->BufferMemoryAlignment = (bd->BufferMemoryAlignment > req.alignment) ? bd->BufferMemoryAlignment : req.alignment;
         VkMemoryAllocateInfo alloc_info = {};
         alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
         alloc_info.allocationSize = req.size;
         alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT, req.memoryTypeBits);
-        err = vkAllocateMemory(v->Device, &alloc_info, v->Allocator, &g_UploadBufferMemory);
+        err = vkAllocateMemory(v->Device, &alloc_info, v->Allocator, &bd->UploadBufferMemory);
         check_vk_result(err);
-        err = vkBindBufferMemory(v->Device, g_UploadBuffer, g_UploadBufferMemory, 0);
+        err = vkBindBufferMemory(v->Device, bd->UploadBuffer, bd->UploadBufferMemory, 0);
         check_vk_result(err);
     }
 
     // Upload to Buffer:
     {
         char* map = NULL;
-        err = vkMapMemory(v->Device, g_UploadBufferMemory, 0, upload_size, 0, (void**)(&map));
+        err = vkMapMemory(v->Device, bd->UploadBufferMemory, 0, upload_size, 0, (void**)(&map));
         check_vk_result(err);
         memcpy(map, pixels, upload_size);
         VkMappedMemoryRange range[1] = {};
         range[0].sType = VK_STRUCTURE_TYPE_MAPPED_MEMORY_RANGE;
-        range[0].memory = g_UploadBufferMemory;
+        range[0].memory = bd->UploadBufferMemory;
         range[0].size = upload_size;
         err = vkFlushMappedMemoryRanges(v->Device, 1, range);
         check_vk_result(err);
-        vkUnmapMemory(v->Device, g_UploadBufferMemory);
+        vkUnmapMemory(v->Device, bd->UploadBufferMemory);
     }
 
     // Copy to Image:
@@ -633,7 +676,7 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
         copy_barrier[0].newLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
         copy_barrier[0].srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
         copy_barrier[0].dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
-        copy_barrier[0].image = g_FontImage;
+        copy_barrier[0].image = bd->FontImage;
         copy_barrier[0].subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
         copy_barrier[0].subresourceRange.levelCount = 1;
         copy_barrier[0].subresourceRange.layerCount = 1;
@@ -645,7 +688,7 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
         region.imageExtent.width = width;
         region.imageExtent.height = height;
         region.imageExtent.depth = 1;
-        vkCmdCopyBufferToImage(command_buffer, g_UploadBuffer, g_FontImage, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 1, &region);
+        vkCmdCopyBufferToImage(command_buffer, bd->UploadBuffer, bd->FontImage, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 1, &region);
 
         VkImageMemoryBarrier use_barrier[1] = {};
         use_barrier[0].sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
@@ -655,7 +698,7 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
         use_barrier[0].newLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
         use_barrier[0].srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
         use_barrier[0].dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
-        use_barrier[0].image = g_FontImage;
+        use_barrier[0].image = bd->FontImage;
         use_barrier[0].subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
         use_barrier[0].subresourceRange.levelCount = 1;
         use_barrier[0].subresourceRange.layerCount = 1;
@@ -663,7 +706,7 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
     }
 
     // Store our identifier
-    io.Fonts->SetTexID((ImTextureID)(intptr_t)g_FontImage);
+    io.Fonts->SetTexID((ImTextureID)bd->FontDescriptorSet);
 
     return true;
 }
@@ -671,29 +714,31 @@ bool ImGui_ImplVulkan_CreateFontsTexture(VkCommandBuffer command_buffer)
 static void ImGui_ImplVulkan_CreateShaderModules(VkDevice device, const VkAllocationCallbacks* allocator)
 {
     // Create the shader modules
-    if (g_ShaderModuleVert == NULL)
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    if (bd->ShaderModuleVert == VK_NULL_HANDLE)
     {
         VkShaderModuleCreateInfo vert_info = {};
         vert_info.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
         vert_info.codeSize = sizeof(__glsl_shader_vert_spv);
         vert_info.pCode = (uint32_t*)__glsl_shader_vert_spv;
-        VkResult err = vkCreateShaderModule(device, &vert_info, allocator, &g_ShaderModuleVert);
+        VkResult err = vkCreateShaderModule(device, &vert_info, allocator, &bd->ShaderModuleVert);
         check_vk_result(err);
     }
-    if (g_ShaderModuleFrag == NULL)
+    if (bd->ShaderModuleFrag == VK_NULL_HANDLE)
     {
         VkShaderModuleCreateInfo frag_info = {};
         frag_info.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
         frag_info.codeSize = sizeof(__glsl_shader_frag_spv);
         frag_info.pCode = (uint32_t*)__glsl_shader_frag_spv;
-        VkResult err = vkCreateShaderModule(device, &frag_info, allocator, &g_ShaderModuleFrag);
+        VkResult err = vkCreateShaderModule(device, &frag_info, allocator, &bd->ShaderModuleFrag);
         check_vk_result(err);
     }
 }
 
 static void ImGui_ImplVulkan_CreateFontSampler(VkDevice device, const VkAllocationCallbacks* allocator)
 {
-    if (g_FontSampler)
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    if (bd->FontSampler)
         return;
 
     VkSamplerCreateInfo info = {};
@@ -707,17 +752,18 @@ static void ImGui_ImplVulkan_CreateFontSampler(VkDevice device, const VkAllocati
     info.minLod = -1000;
     info.maxLod = 1000;
     info.maxAnisotropy = 1.0f;
-    VkResult err = vkCreateSampler(device, &info, allocator, &g_FontSampler);
+    VkResult err = vkCreateSampler(device, &info, allocator, &bd->FontSampler);
     check_vk_result(err);
 }
 
 static void ImGui_ImplVulkan_CreateDescriptorSetLayout(VkDevice device, const VkAllocationCallbacks* allocator)
 {
-    if (g_DescriptorSetLayout)
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    if (bd->DescriptorSetLayout)
         return;
 
     ImGui_ImplVulkan_CreateFontSampler(device, allocator);
-    VkSampler sampler[1] = { g_FontSampler };
+    VkSampler sampler[1] = { bd->FontSampler };
     VkDescriptorSetLayoutBinding binding[1] = {};
     binding[0].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
     binding[0].descriptorCount = 1;
@@ -727,13 +773,14 @@ static void ImGui_ImplVulkan_CreateDescriptorSetLayout(VkDevice device, const Vk
     info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO;
     info.bindingCount = 1;
     info.pBindings = binding;
-    VkResult err = vkCreateDescriptorSetLayout(device, &info, allocator, &g_DescriptorSetLayout);
+    VkResult err = vkCreateDescriptorSetLayout(device, &info, allocator, &bd->DescriptorSetLayout);
     check_vk_result(err);
 }
 
 static void ImGui_ImplVulkan_CreatePipelineLayout(VkDevice device, const VkAllocationCallbacks* allocator)
 {
-    if (g_PipelineLayout)
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    if (bd->PipelineLayout)
         return;
 
     // Constants: we are using 'vec2 offset' and 'vec2 scale' instead of a full 3d projection matrix
@@ -742,29 +789,30 @@ static void ImGui_ImplVulkan_CreatePipelineLayout(VkDevice device, const VkAlloc
     push_constants[0].stageFlags = VK_SHADER_STAGE_VERTEX_BIT;
     push_constants[0].offset = sizeof(float) * 0;
     push_constants[0].size = sizeof(float) * 4;
-    VkDescriptorSetLayout set_layout[1] = { g_DescriptorSetLayout };
+    VkDescriptorSetLayout set_layout[1] = { bd->DescriptorSetLayout };
     VkPipelineLayoutCreateInfo layout_info = {};
     layout_info.sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO;
     layout_info.setLayoutCount = 1;
     layout_info.pSetLayouts = set_layout;
     layout_info.pushConstantRangeCount = 1;
     layout_info.pPushConstantRanges = push_constants;
-    VkResult  err = vkCreatePipelineLayout(device, &layout_info, allocator, &g_PipelineLayout);
+    VkResult  err = vkCreatePipelineLayout(device, &layout_info, allocator, &bd->PipelineLayout);
     check_vk_result(err);
 }
 
 static void ImGui_ImplVulkan_CreatePipeline(VkDevice device, const VkAllocationCallbacks* allocator, VkPipelineCache pipelineCache, VkRenderPass renderPass, VkSampleCountFlagBits MSAASamples, VkPipeline* pipeline, uint32_t subpass)
 {
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
     ImGui_ImplVulkan_CreateShaderModules(device, allocator);
 
     VkPipelineShaderStageCreateInfo stage[2] = {};
     stage[0].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
     stage[0].stage = VK_SHADER_STAGE_VERTEX_BIT;
-    stage[0].module = g_ShaderModuleVert;
+    stage[0].module = bd->ShaderModuleVert;
     stage[0].pName = "main";
     stage[1].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
     stage[1].stage = VK_SHADER_STAGE_FRAGMENT_BIT;
-    stage[1].module = g_ShaderModuleFrag;
+    stage[1].module = bd->ShaderModuleFrag;
     stage[1].pName = "main";
 
     VkVertexInputBindingDescription binding_desc[1] = {};
@@ -840,7 +888,7 @@ static void ImGui_ImplVulkan_CreatePipeline(VkDevice device, const VkAllocationC
 
     VkGraphicsPipelineCreateInfo info = {};
     info.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO;
-    info.flags = g_PipelineCreateFlags;
+    info.flags = bd->PipelineCreateFlags;
     info.stageCount = 2;
     info.pStages = stage;
     info.pVertexInputState = &vertex_info;
@@ -851,7 +899,7 @@ static void ImGui_ImplVulkan_CreatePipeline(VkDevice device, const VkAllocationC
     info.pDepthStencilState = &depth_info;
     info.pColorBlendState = &blend_info;
     info.pDynamicState = &dynamic_state;
-    info.layout = g_PipelineLayout;
+    info.layout = bd->PipelineLayout;
     info.renderPass = renderPass;
     info.subpass = subpass;
     VkResult err = vkCreateGraphicsPipelines(device, pipelineCache, 1, &info, allocator, pipeline);
@@ -860,10 +908,11 @@ static void ImGui_ImplVulkan_CreatePipeline(VkDevice device, const VkAllocationC
 
 bool ImGui_ImplVulkan_CreateDeviceObjects()
 {
-    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
     VkResult err;
 
-    if (!g_FontSampler)
+    if (!bd->FontSampler)
     {
         VkSamplerCreateInfo info = {};
         info.sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO;
@@ -876,13 +925,13 @@ bool ImGui_ImplVulkan_CreateDeviceObjects()
         info.minLod = -1000;
         info.maxLod = 1000;
         info.maxAnisotropy = 1.0f;
-        err = vkCreateSampler(v->Device, &info, v->Allocator, &g_FontSampler);
+        err = vkCreateSampler(v->Device, &info, v->Allocator, &bd->FontSampler);
         check_vk_result(err);
     }
 
-    if (!g_DescriptorSetLayout)
+    if (!bd->DescriptorSetLayout)
     {
-        VkSampler sampler[1] = {g_FontSampler};
+        VkSampler sampler[1] = {bd->FontSampler};
         VkDescriptorSetLayoutBinding binding[1] = {};
         binding[0].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
         binding[0].descriptorCount = 1;
@@ -892,74 +941,65 @@ bool ImGui_ImplVulkan_CreateDeviceObjects()
         info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO;
         info.bindingCount = 1;
         info.pBindings = binding;
-        err = vkCreateDescriptorSetLayout(v->Device, &info, v->Allocator, &g_DescriptorSetLayout);
+        err = vkCreateDescriptorSetLayout(v->Device, &info, v->Allocator, &bd->DescriptorSetLayout);
         check_vk_result(err);
     }
 
-    // Create Descriptor Set:
-    {
-        VkDescriptorSetAllocateInfo alloc_info = {};
-        alloc_info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO;
-        alloc_info.descriptorPool = v->DescriptorPool;
-        alloc_info.descriptorSetCount = 1;
-        alloc_info.pSetLayouts = &g_DescriptorSetLayout;
-        err = vkAllocateDescriptorSets(v->Device, &alloc_info, &g_DescriptorSet);
-        check_vk_result(err);
-    }
-
-    if (!g_PipelineLayout)
+    if (!bd->PipelineLayout)
     {
         // Constants: we are using 'vec2 offset' and 'vec2 scale' instead of a full 3d projection matrix
         VkPushConstantRange push_constants[1] = {};
         push_constants[0].stageFlags = VK_SHADER_STAGE_VERTEX_BIT;
         push_constants[0].offset = sizeof(float) * 0;
         push_constants[0].size = sizeof(float) * 4;
-        VkDescriptorSetLayout set_layout[1] = { g_DescriptorSetLayout };
+        VkDescriptorSetLayout set_layout[1] = { bd->DescriptorSetLayout };
         VkPipelineLayoutCreateInfo layout_info = {};
         layout_info.sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO;
         layout_info.setLayoutCount = 1;
         layout_info.pSetLayouts = set_layout;
         layout_info.pushConstantRangeCount = 1;
         layout_info.pPushConstantRanges = push_constants;
-        err = vkCreatePipelineLayout(v->Device, &layout_info, v->Allocator, &g_PipelineLayout);
+        err = vkCreatePipelineLayout(v->Device, &layout_info, v->Allocator, &bd->PipelineLayout);
         check_vk_result(err);
     }
 
-    ImGui_ImplVulkan_CreatePipeline(v->Device, v->Allocator, v->PipelineCache, g_RenderPass, v->MSAASamples, &g_Pipeline, g_Subpass);
+    ImGui_ImplVulkan_CreatePipeline(v->Device, v->Allocator, v->PipelineCache, bd->RenderPass, v->MSAASamples, &bd->Pipeline, bd->Subpass);
 
     return true;
 }
 
 void    ImGui_ImplVulkan_DestroyFontUploadObjects()
 {
-    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
-    if (g_UploadBuffer)
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+    if (bd->UploadBuffer)
     {
-        vkDestroyBuffer(v->Device, g_UploadBuffer, v->Allocator);
-        g_UploadBuffer = VK_NULL_HANDLE;
+        vkDestroyBuffer(v->Device, bd->UploadBuffer, v->Allocator);
+        bd->UploadBuffer = VK_NULL_HANDLE;
     }
-    if (g_UploadBufferMemory)
+    if (bd->UploadBufferMemory)
     {
-        vkFreeMemory(v->Device, g_UploadBufferMemory, v->Allocator);
-        g_UploadBufferMemory = VK_NULL_HANDLE;
+        vkFreeMemory(v->Device, bd->UploadBufferMemory, v->Allocator);
+        bd->UploadBufferMemory = VK_NULL_HANDLE;
     }
 }
 
 void    ImGui_ImplVulkan_DestroyDeviceObjects()
 {
-    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
-    ImGui_ImplVulkanH_DestroyWindowRenderBuffers(v->Device, &g_MainWindowRenderBuffers, v->Allocator);
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+    ImGui_ImplVulkanH_DestroyWindowRenderBuffers(v->Device, &bd->MainWindowRenderBuffers, v->Allocator);
     ImGui_ImplVulkan_DestroyFontUploadObjects();
 
-    if (g_ShaderModuleVert)     { vkDestroyShaderModule(v->Device, g_ShaderModuleVert, v->Allocator); g_ShaderModuleVert = VK_NULL_HANDLE; }
-    if (g_ShaderModuleFrag)     { vkDestroyShaderModule(v->Device, g_ShaderModuleFrag, v->Allocator); g_ShaderModuleFrag = VK_NULL_HANDLE; }
-    if (g_FontView)             { vkDestroyImageView(v->Device, g_FontView, v->Allocator); g_FontView = VK_NULL_HANDLE; }
-    if (g_FontImage)            { vkDestroyImage(v->Device, g_FontImage, v->Allocator); g_FontImage = VK_NULL_HANDLE; }
-    if (g_FontMemory)           { vkFreeMemory(v->Device, g_FontMemory, v->Allocator); g_FontMemory = VK_NULL_HANDLE; }
-    if (g_FontSampler)          { vkDestroySampler(v->Device, g_FontSampler, v->Allocator); g_FontSampler = VK_NULL_HANDLE; }
-    if (g_DescriptorSetLayout)  { vkDestroyDescriptorSetLayout(v->Device, g_DescriptorSetLayout, v->Allocator); g_DescriptorSetLayout = VK_NULL_HANDLE; }
-    if (g_PipelineLayout)       { vkDestroyPipelineLayout(v->Device, g_PipelineLayout, v->Allocator); g_PipelineLayout = VK_NULL_HANDLE; }
-    if (g_Pipeline)             { vkDestroyPipeline(v->Device, g_Pipeline, v->Allocator); g_Pipeline = VK_NULL_HANDLE; }
+    if (bd->ShaderModuleVert)     { vkDestroyShaderModule(v->Device, bd->ShaderModuleVert, v->Allocator); bd->ShaderModuleVert = VK_NULL_HANDLE; }
+    if (bd->ShaderModuleFrag)     { vkDestroyShaderModule(v->Device, bd->ShaderModuleFrag, v->Allocator); bd->ShaderModuleFrag = VK_NULL_HANDLE; }
+    if (bd->FontView)             { vkDestroyImageView(v->Device, bd->FontView, v->Allocator); bd->FontView = VK_NULL_HANDLE; }
+    if (bd->FontImage)            { vkDestroyImage(v->Device, bd->FontImage, v->Allocator); bd->FontImage = VK_NULL_HANDLE; }
+    if (bd->FontMemory)           { vkFreeMemory(v->Device, bd->FontMemory, v->Allocator); bd->FontMemory = VK_NULL_HANDLE; }
+    if (bd->FontSampler)          { vkDestroySampler(v->Device, bd->FontSampler, v->Allocator); bd->FontSampler = VK_NULL_HANDLE; }
+    if (bd->DescriptorSetLayout)  { vkDestroyDescriptorSetLayout(v->Device, bd->DescriptorSetLayout, v->Allocator); bd->DescriptorSetLayout = VK_NULL_HANDLE; }
+    if (bd->PipelineLayout)       { vkDestroyPipelineLayout(v->Device, bd->PipelineLayout, v->Allocator); bd->PipelineLayout = VK_NULL_HANDLE; }
+    if (bd->Pipeline)             { vkDestroyPipeline(v->Device, bd->Pipeline, v->Allocator); bd->Pipeline = VK_NULL_HANDLE; }
 }
 
 bool    ImGui_ImplVulkan_LoadFunctions(PFN_vkVoidFunction(*loader_func)(const char* function_name, void* user_data), void* user_data)
@@ -987,8 +1027,12 @@ bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass rend
 {
     IM_ASSERT(g_FunctionsLoaded && "Need to call ImGui_ImplVulkan_LoadFunctions() if IMGUI_IMPL_VULKAN_NO_PROTOTYPES or VK_NO_PROTOTYPES are set!");
 
-    // Setup backend capabilities flags
     ImGuiIO& io = ImGui::GetIO();
+    IM_ASSERT(io.BackendRendererUserData == NULL && "Already initialized a renderer backend!");
+
+    // Setup backend capabilities flags
+    ImGui_ImplVulkan_Data* bd = IM_NEW(ImGui_ImplVulkan_Data)();
+    io.BackendRendererUserData = (void*)bd;
     io.BackendRendererName = "imgui_impl_vulkan";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
 
@@ -1001,9 +1045,9 @@ bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass rend
     IM_ASSERT(info->ImageCount >= info->MinImageCount);
     IM_ASSERT(render_pass != VK_NULL_HANDLE);
 
-    g_VulkanInitInfo = *info;
-    g_RenderPass = render_pass;
-    g_Subpass = info->Subpass;
+    bd->VulkanInitInfo = *info;
+    bd->RenderPass = render_pass;
+    bd->Subpass = info->Subpass;
 
     ImGui_ImplVulkan_CreateDeviceObjects();
 
@@ -1012,26 +1056,72 @@ bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info, VkRenderPass rend
 
 void ImGui_ImplVulkan_Shutdown()
 {
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    IM_ASSERT(bd != NULL && "No renderer backend to shutdown, or already shutdown?");
+    ImGuiIO& io = ImGui::GetIO();
+
     ImGui_ImplVulkan_DestroyDeviceObjects();
+    io.BackendRendererName = NULL;
+    io.BackendRendererUserData = NULL;
+    IM_DELETE(bd);
 }
 
 void ImGui_ImplVulkan_NewFrame()
 {
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    IM_ASSERT(bd != NULL && "Did you call ImGui_ImplVulkan_Init()?");
+    IM_UNUSED(bd);
 }
 
 void ImGui_ImplVulkan_SetMinImageCount(uint32_t min_image_count)
 {
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
     IM_ASSERT(min_image_count >= 2);
-    if (g_VulkanInitInfo.MinImageCount == min_image_count)
+    if (bd->VulkanInitInfo.MinImageCount == min_image_count)
         return;
 
-    ImGui_ImplVulkan_InitInfo* v = &g_VulkanInitInfo;
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
     VkResult err = vkDeviceWaitIdle(v->Device);
     check_vk_result(err);
-    ImGui_ImplVulkanH_DestroyWindowRenderBuffers(v->Device, &g_MainWindowRenderBuffers, v->Allocator);
-    g_VulkanInitInfo.MinImageCount = min_image_count;
+    ImGui_ImplVulkanH_DestroyWindowRenderBuffers(v->Device, &bd->MainWindowRenderBuffers, v->Allocator);
+    bd->VulkanInitInfo.MinImageCount = min_image_count;
 }
 
+// Register a texture
+// FIXME: This is experimental in the sense that we are unsure how to best design/tackle this problem, please post to https://github.com/ocornut/imgui/pull/914 if you have suggestions.
+VkDescriptorSet ImGui_ImplVulkan_AddTexture(VkSampler sampler, VkImageView image_view, VkImageLayout image_layout)
+{
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+
+    // Create Descriptor Set:
+    VkDescriptorSet descriptor_set;
+    {
+        VkDescriptorSetAllocateInfo alloc_info = {};
+        alloc_info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO;
+        alloc_info.descriptorPool = v->DescriptorPool;
+        alloc_info.descriptorSetCount = 1;
+        alloc_info.pSetLayouts = &bd->DescriptorSetLayout;
+        VkResult err = vkAllocateDescriptorSets(v->Device, &alloc_info, &descriptor_set);
+        check_vk_result(err);
+    }
+
+    // Update the Descriptor Set:
+    {
+        VkDescriptorImageInfo desc_image[1] = {};
+        desc_image[0].sampler = sampler;
+        desc_image[0].imageView = image_view;
+        desc_image[0].imageLayout = image_layout;
+        VkWriteDescriptorSet write_desc[1] = {};
+        write_desc[0].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
+        write_desc[0].dstSet = descriptor_set;
+        write_desc[0].descriptorCount = 1;
+        write_desc[0].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
+        write_desc[0].pImageInfo = desc_image;
+        vkUpdateDescriptorSets(v->Device, 1, write_desc, 0, NULL);
+    }
+    return descriptor_set;
+}
 
 //-------------------------------------------------------------------------
 // Internal / Miscellaneous Vulkan Helpers
@@ -1181,7 +1271,7 @@ void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, V
 {
     VkResult err;
     VkSwapchainKHR old_swapchain = wd->Swapchain;
-    wd->Swapchain = NULL;
+    wd->Swapchain = VK_NULL_HANDLE;
     err = vkDeviceWaitIdle(device);
     check_vk_result(err);
 
@@ -1299,7 +1389,7 @@ void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, V
 
         // We do not create a pipeline by default as this is also used by examples' main.cpp,
         // but secondary viewport in multi-viewport mode may want to create one with:
-        //ImGui_ImplVulkan_CreatePipeline(device, allocator, VK_NULL_HANDLE, wd->RenderPass, VK_SAMPLE_COUNT_1_BIT, &wd->Pipeline, g_Subpass);
+        //ImGui_ImplVulkan_CreatePipeline(device, allocator, VK_NULL_HANDLE, wd->RenderPass, VK_SAMPLE_COUNT_1_BIT, &wd->Pipeline, bd->Subpass);
     }
 
     // Create The Image Views
@@ -1356,7 +1446,7 @@ void ImGui_ImplVulkanH_CreateOrResizeWindow(VkInstance instance, VkPhysicalDevic
 void ImGui_ImplVulkanH_DestroyWindow(VkInstance instance, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator)
 {
     vkDeviceWaitIdle(device); // FIXME: We could wait on the Queue if we had the queue in wd-> (otherwise VulkanH functions can't use globals)
-    //vkQueueWaitIdle(g_Queue);
+    //vkQueueWaitIdle(bd->Queue);
 
     for (uint32_t i = 0; i < wd->ImageCount; i++)
     {