From 4778560e668b8ad1dae177a7819ed66675630c63 Mon Sep 17 00:00:00 2001
From: Tristan Gouge <gouge.tristan@gmail.com>
Date: Tue, 2 Jan 2024 17:06:21 +0100
Subject: [PATCH] Backends: Vulkan: Added MinAllocationSize field in
 ImGui_ImplVulkan_InitInfo to workaround zealous validation layer. (#7189,
 #4238)

---
 backends/imgui_impl_vulkan.cpp | 13 +++++++++----
 backends/imgui_impl_vulkan.h   |  1 +
 docs/CHANGELOG.txt             |  2 ++
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/backends/imgui_impl_vulkan.cpp b/backends/imgui_impl_vulkan.cpp
index 94e9a0f7c..7a9205a74 100644
--- a/backends/imgui_impl_vulkan.cpp
+++ b/backends/imgui_impl_vulkan.cpp
@@ -33,6 +33,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-01-03: Vulkan: Added MinAllocationSize field in ImGui_ImplVulkan_InitInfo to workaround zealous "best practice" validation layer. (#7189, #4238)
 //  2023-11-29: Vulkan: Fixed mismatching allocator passed to vkCreateCommandPool() vs vkDestroyCommandPool(). (#7075)
 //  2023-11-10: *BREAKING CHANGE*: Removed parameter from ImGui_ImplVulkan_CreateFontsTexture(): backend now creates its own command-buffer to upload fonts.
 //              *BREAKING CHANGE*: Removed ImGui_ImplVulkan_DestroyFontUploadObjects() which is now unecessary as we create and destroy those objects in the backend.
@@ -79,6 +80,9 @@
 #ifndef IMGUI_DISABLE
 #include "imgui_impl_vulkan.h"
 #include <stdio.h>
+#ifndef IM_MAX
+#define IM_MAX(A, B)    (((A) >= (B)) ? (A) : (B))
+#endif
 
 // Visual Studio warnings
 #ifdef _MSC_VER
@@ -400,16 +404,17 @@ static void CreateOrResizeBuffer(VkBuffer& buffer, VkDeviceMemory& buffer_memory
     VkMemoryRequirements req;
     vkGetBufferMemoryRequirements(v->Device, buffer, &req);
     bd->BufferMemoryAlignment = (bd->BufferMemoryAlignment > req.alignment) ? bd->BufferMemoryAlignment : req.alignment;
+    VkDeviceSize size = IM_MAX(v->MinAllocationSize, req.size);
     VkMemoryAllocateInfo alloc_info = {};
     alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
-    alloc_info.allocationSize = req.size;
+    alloc_info.allocationSize = size;
     alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT, req.memoryTypeBits);
     err = vkAllocateMemory(v->Device, &alloc_info, v->Allocator, &buffer_memory);
     check_vk_result(err);
 
     err = vkBindBufferMemory(v->Device, buffer, buffer_memory, 0);
     check_vk_result(err);
-    p_buffer_size = req.size;
+    p_buffer_size = size;
 }
 
 static void ImGui_ImplVulkan_SetupRenderState(ImDrawData* draw_data, VkPipeline pipeline, VkCommandBuffer command_buffer, ImGui_ImplVulkanH_FrameRenderBuffers* rb, int fb_width, int fb_height)
@@ -669,7 +674,7 @@ bool ImGui_ImplVulkan_CreateFontsTexture()
         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.allocationSize = IM_MAX(v->MinAllocationSize, req.size);
         alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, req.memoryTypeBits);
         err = vkAllocateMemory(v->Device, &alloc_info, v->Allocator, &bd->FontMemory);
         check_vk_result(err);
@@ -710,7 +715,7 @@ bool ImGui_ImplVulkan_CreateFontsTexture()
         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.allocationSize = IM_MAX(v->MinAllocationSize, req.size);
         alloc_info.memoryTypeIndex = ImGui_ImplVulkan_MemoryType(VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT, req.memoryTypeBits);
         err = vkAllocateMemory(v->Device, &alloc_info, v->Allocator, &upload_buffer_memory);
         check_vk_result(err);
diff --git a/backends/imgui_impl_vulkan.h b/backends/imgui_impl_vulkan.h
index c53ba6881..490fbb040 100644
--- a/backends/imgui_impl_vulkan.h
+++ b/backends/imgui_impl_vulkan.h
@@ -71,6 +71,7 @@ struct ImGui_ImplVulkan_InitInfo
     // Allocation, Debugging
     const VkAllocationCallbacks*    Allocator;
     void                            (*CheckVkResultFn)(VkResult err);
+    VkDeviceSize                    MinAllocationSize;      // Minimum allocation size. Set to 1024*1024 to satisfy zealous best practices validation layer and waste a little memory.
 };
 
 // Called by user code
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index d699d6146..16afae940 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -96,6 +96,8 @@ Other changes:
   compiling in MBCS mode. (#7174) [@kimidaisuki22]
 - Backends: Vulkan: Fixed mismatching allocator passed to vkCreateCommandPool() vs
   vkDestroyCommandPool(). (#7075) [@FoonTheRaccoon]
+- Backends: Vulkan: Added MinAllocationSize field in ImGui_ImplVulkan_InitInfo to workaround zealous
+  "best practice" validation layer. (#7189, #4238) [@philae-ael]
 - Backends: WebGPU: Fixed wgpuRenderPassEncoderSetScissorRect() crash when rendering modal
   window's dimming layer, which has an unclipped value in ImDrawCmd::ClipRect. (#7191) [@aparis69]
 - Examples: GLFW+Emscripten: Fixed examples not consistently resizing according to host canvas.