First pass at VulkanViewer

tools/vulkan/VulkanTestContext.cpp

+
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrContext.h"
+#include "SkSurface.h"
+#include "VulkanTestContext.h"
+
+#include "../../src/gpu/vk/GrVkMemory.h"
+#include "vk/GrVkInterface.h"
+#include "../../src/gpu/vk/GrVkUtil.h"
+#include "vk/GrVkTypes.h"
+
+#ifdef VK_USE_PLATFORM_WIN32_KHR
+// windows wants to define this as CreateSemaphoreA or CreateSemaphoreW
+#undef CreateSemaphore
+#endif
+
+VulkanTestContext::VulkanTestContext(void* platformData, int msaaSampleCount) 
+                                 : fSurface(VK_NULL_HANDLE)
+                                 , fSwapchain(VK_NULL_HANDLE)
+                                 , fCommandPool(VK_NULL_HANDLE)
+                                 , fBackbuffers(nullptr)
+{
+
+    // any config code here (particularly for msaa)?
+
+    this->initializeContext(platformData);
+}
+
+void VulkanTestContext::initializeContext(void* platformData) {
+
+    fBackendContext.reset(GrVkBackendContext::Create());
+    fBackendContext->ref();
+
+    fContext = GrContext::Create(kVulkan_GrBackend, (GrBackendContext)fBackendContext.get());
+
+    fSurface = createVkSurface(platformData);
+    if (VK_NULL_HANDLE == fSurface) {
+        fBackendContext.reset(nullptr);
+        return;
+    }
+
+    // query to get the initial queue props size
+    uint32_t queueCount;
+    GR_VK_CALL(fBackendContext->fInterface, 
+               GetPhysicalDeviceQueueFamilyProperties(fBackendContext->fPhysicalDevice, &queueCount,
+                                                      nullptr));
+    SkASSERT(queueCount >= 1);
+
+    SkAutoMalloc queuePropsAlloc(queueCount * sizeof(VkQueueFamilyProperties));
+    // now get the actual queue props
+    VkQueueFamilyProperties* queueProps = (VkQueueFamilyProperties*)queuePropsAlloc.get();
+
+    GR_VK_CALL(fBackendContext->fInterface,
+               GetPhysicalDeviceQueueFamilyProperties(fBackendContext->fPhysicalDevice, &queueCount,
+                                                      queueProps));
+
+    // iterate to find the present queue
+    fPresentQueueIndex = -1;
+    for (uint32_t i = 0; i < queueCount; i++) {
+        if ((queueProps[i].queueFlags & VK_QUEUE_GRAPHICS_BIT) && canPresent(i)) {
+            fPresentQueueIndex = i;
+            break;
+        }
+    }
+    SkASSERT(fPresentQueueIndex < queueCount);
+
+    VkBool32 supported;
+    VkResult res = GR_VK_CALL(fBackendContext->fInterface,
+                              GetPhysicalDeviceSurfaceSupportKHR(
+                              fBackendContext->fPhysicalDevice,
+                              fPresentQueueIndex,
+                              fSurface,
+                              &supported));
+    if (VK_SUCCESS != res) {
+        this->destroyContext();
+        return;
+    }
+
+    // get this info from somewhere?
+    if (!this->createSwapchain(1024, 768)) {
+        this->destroyContext();
+        return;
+    }
+
+    // create presentQueue
+    vkGetDeviceQueue(fBackendContext->fDevice, fPresentQueueIndex, 0, &fPresentQueue);
+
+
+}
+
+bool VulkanTestContext::createSwapchain(uint32_t width, uint32_t height)
+{
+    // check for capabilities
+    VkSurfaceCapabilitiesKHR caps;
+    VkResult res = GR_VK_CALL(fBackendContext->fInterface,
+                              GetPhysicalDeviceSurfaceCapabilitiesKHR(fBackendContext->fPhysicalDevice,
+                              fSurface,
+                              &caps));
+    if (VK_SUCCESS != res) {
+        return false;
+    }
+
+    uint32_t surfaceFormatCount;
+    res = GR_VK_CALL(fBackendContext->fInterface,
+                     GetPhysicalDeviceSurfaceFormatsKHR(fBackendContext->fPhysicalDevice,
+                                                        fSurface,
+                                                        &surfaceFormatCount,
+                                                        nullptr));
+    if (VK_SUCCESS != res) {
+        return false;
+    }
+
+    SkAutoMalloc surfaceFormatAlloc(surfaceFormatCount * sizeof(VkSurfaceFormatKHR));
+    VkSurfaceFormatKHR* surfaceFormats = (VkSurfaceFormatKHR*)surfaceFormatAlloc.get();
+    res = GR_VK_CALL(fBackendContext->fInterface,
+                     GetPhysicalDeviceSurfaceFormatsKHR(fBackendContext->fPhysicalDevice,
+                     fSurface,
+                     &surfaceFormatCount,
+                     surfaceFormats));
+    if (VK_SUCCESS != res) {
+        return false;
+    }
+
+    uint32_t presentModeCount;
+    res = GR_VK_CALL(fBackendContext->fInterface,
+                     GetPhysicalDeviceSurfacePresentModesKHR(fBackendContext->fPhysicalDevice,
+                     fSurface,
+                     &presentModeCount,
+                     nullptr));
+    if (VK_SUCCESS != res) {
+        return false;
+    }
+
+    SkAutoMalloc presentModeAlloc(presentModeCount * sizeof(VkPresentModeKHR));
+    VkPresentModeKHR* presentModes = (VkPresentModeKHR*)presentModeAlloc.get();
+    res = GR_VK_CALL(fBackendContext->fInterface,
+                     GetPhysicalDeviceSurfacePresentModesKHR(fBackendContext->fPhysicalDevice,
+                     fSurface,
+                     &presentModeCount,
+                     presentModes));
+    if (VK_SUCCESS != res) {
+        return false;
+    }
+
+    VkExtent2D extent = caps.currentExtent;
+    // use the hints
+    if (extent.width == (uint32_t)-1) {
+        extent.width = width;
+        extent.height = height;
+    }
+
+    // clamp width; to protect us from broken hints?
+    if (extent.width < caps.minImageExtent.width) {
+        extent.width = caps.minImageExtent.width;
+    } else if (extent.width > caps.maxImageExtent.width) {
+        extent.width = caps.maxImageExtent.width;
+    }
+    // clamp height
+    if (extent.height < caps.minImageExtent.height) {
+        extent.height = caps.minImageExtent.height;
+    } else if (extent.height > caps.maxImageExtent.height) {
+        extent.height = caps.maxImageExtent.height;
+    }
+    fWidth = (int)extent.width;
+    fHeight = (int)extent.height;
+
+    // not sure what the point of this is
+    //if (ctx_.extent.width == extent.width && ctx_.extent.height == extent.height)
+    //    return;
+
+    uint32_t imageCount = caps.minImageCount + 2;
+    if (caps.maxImageCount > 0 && imageCount > caps.maxImageCount) {
+        // Application must settle for fewer images than desired:
+        imageCount = caps.maxImageCount;
+    }
+
+    VkImageUsageFlags usageFlags = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;// |
+                                   //VK_IMAGE_USAGE_TRANSFER_SRC_BIT |
+                                   //VK_IMAGE_USAGE_TRANSFER_DST_BIT;
+    SkASSERT((caps.supportedUsageFlags & usageFlags) == usageFlags);
+    SkASSERT(caps.supportedTransforms & caps.currentTransform);
+    SkASSERT(caps.supportedCompositeAlpha & (VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR |
+        VK_COMPOSITE_ALPHA_INHERIT_BIT_KHR));
+    VkCompositeAlphaFlagBitsKHR composite_alpha =
+        (caps.supportedCompositeAlpha & VK_COMPOSITE_ALPHA_INHERIT_BIT_KHR) ?
+                                       VK_COMPOSITE_ALPHA_INHERIT_BIT_KHR :
+                                       VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
+
+    // FIFO is the only mode universally supported
+    VkPresentModeKHR mode = VK_PRESENT_MODE_FIFO_KHR;
+    bool vsync = false;
+    for (uint32_t i = 0; i < presentModeCount; ++i) {
+        if ((vsync && VK_PRESENT_MODE_MAILBOX_KHR == presentModes[i]) ||
+            (!vsync && VK_PRESENT_MODE_IMMEDIATE_KHR == presentModes[i])) {
+            mode = presentModes[i];
+        }
+    }
+
+    VkSwapchainCreateInfoKHR swapchainCreateInfo;
+    memset(&swapchainCreateInfo, 0, sizeof(VkSwapchainCreateInfoKHR));
+    swapchainCreateInfo.sType = VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR;
+    swapchainCreateInfo.surface = fSurface;
+    swapchainCreateInfo.minImageCount = imageCount;
+    swapchainCreateInfo.imageFormat = surfaceFormats[0].format;       // for now, use the first one
+    swapchainCreateInfo.imageColorSpace = surfaceFormats[0].colorSpace;
+    swapchainCreateInfo.imageExtent = extent;
+    swapchainCreateInfo.imageArrayLayers = 1;
+    swapchainCreateInfo.imageUsage = usageFlags;
+
+    uint32_t queueFamilies[] = { fBackendContext->fQueueFamilyIndex, fPresentQueueIndex };
+    if (fBackendContext->fQueueFamilyIndex != fPresentQueueIndex) {
+        swapchainCreateInfo.imageSharingMode = VK_SHARING_MODE_CONCURRENT;
+        swapchainCreateInfo.queueFamilyIndexCount = 2;
+        swapchainCreateInfo.pQueueFamilyIndices = queueFamilies;
+    } else {
+        swapchainCreateInfo.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;
+        swapchainCreateInfo.queueFamilyIndexCount = 0;
+        swapchainCreateInfo.pQueueFamilyIndices = nullptr;
+    }
+
+    swapchainCreateInfo.preTransform = caps.currentTransform;;
+    swapchainCreateInfo.compositeAlpha = composite_alpha;
+    swapchainCreateInfo.presentMode = mode;
+    swapchainCreateInfo.clipped = true;
+    swapchainCreateInfo.oldSwapchain = fSwapchain;
+
+    res = GR_VK_CALL(fBackendContext->fInterface,
+                     CreateSwapchainKHR(fBackendContext->fDevice,
+                                        &swapchainCreateInfo, nullptr, &fSwapchain));
+    if (VK_SUCCESS != res) {
+        return false;
+    }
+
+    // destroy the old swapchain
+    if (swapchainCreateInfo.oldSwapchain != VK_NULL_HANDLE) {
+        GR_VK_CALL(fBackendContext->fInterface, DeviceWaitIdle(fBackendContext->fDevice));
+
+        this->destroyBuffers();
+
+        GR_VK_CALL(fBackendContext->fInterface, DestroySwapchainKHR(fBackendContext->fDevice,
+                                                                   swapchainCreateInfo.oldSwapchain,
+                                                                   nullptr));
+    }
+
+    GrVkFormatToPixelConfig(swapchainCreateInfo.imageFormat, &fPixelConfig);
+
+    this->createBuffers();
+
+    return true;
+}
+
+void VulkanTestContext::createBuffers() {
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface, GetSwapchainImagesKHR(fBackendContext->fDevice,
+                                                                           fSwapchain,
+                                                                           &fImageCount,
+                                                                           nullptr));
+    SkASSERT(fImageCount);
+    fImages = new VkImage[fImageCount];
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface, GetSwapchainImagesKHR(fBackendContext->fDevice,
+                                                                           fSwapchain,
+                                                                           &fImageCount,
+                                                                           fImages));
+
+    // set up initial image layouts and create surfaces
+    fImageLayouts = new VkImageLayout[fImageCount];
+    fSurfaces = new sk_sp<SkSurface>[fImageCount];
+    for (uint32_t i = 0; i < fImageCount; ++i) {
+        fImageLayouts[i] = VK_IMAGE_LAYOUT_UNDEFINED;
+
+        GrBackendRenderTargetDesc desc;
+        GrVkTextureInfo info;
+        info.fImage = fImages[i];
+        info.fAlloc = nullptr;
+        info.fImageLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+        info.fImageTiling = VK_IMAGE_TILING_OPTIMAL;
+        desc.fWidth = fWidth;
+        desc.fHeight = fHeight;
+        desc.fConfig = fPixelConfig;
+        desc.fOrigin = kTopLeft_GrSurfaceOrigin;
+        desc.fSampleCnt = 0;
+        desc.fStencilBits = 0;
+        desc.fRenderTargetHandle = (GrBackendObject) &info;
+        SkSurfaceProps props(0, kUnknown_SkPixelGeometry);
+        fSurfaces[i] = SkSurface::MakeFromBackendRenderTarget(fContext, desc, &props);
+    }
+
+    // create the command pool for the command buffers
+    if (VK_NULL_HANDLE == fCommandPool) {
+        VkCommandPoolCreateInfo commandPoolInfo;
+        memset(&commandPoolInfo, 0, sizeof(VkCommandPoolCreateInfo));
+        commandPoolInfo.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
+        // this needs to be on the render queue
+        commandPoolInfo.queueFamilyIndex = fBackendContext->fQueueFamilyIndex;
+        commandPoolInfo.flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT;
+        GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                            CreateCommandPool(fBackendContext->fDevice, &commandPoolInfo,
+                                              nullptr, &fCommandPool));
+    }
+
+    // set up the backbuffers
+    VkSemaphoreCreateInfo semaphoreInfo;
+    memset(&semaphoreInfo, 0, sizeof(VkSemaphoreCreateInfo));
+    semaphoreInfo.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;
+    semaphoreInfo.pNext = nullptr;
+    semaphoreInfo.flags = 0;
+    VkCommandBufferAllocateInfo commandBuffersInfo;
+    memset(&commandBuffersInfo, 0, sizeof(VkCommandBufferAllocateInfo));
+    commandBuffersInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
+    commandBuffersInfo.pNext = nullptr;
+    commandBuffersInfo.commandPool = fCommandPool;
+    commandBuffersInfo.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
+    commandBuffersInfo.commandBufferCount = 2;
+    VkFenceCreateInfo fenceInfo;
+    memset(&fenceInfo, 0, sizeof(VkFenceCreateInfo));
+    fenceInfo.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO;
+    fenceInfo.pNext = nullptr;
+    fenceInfo.flags = VK_FENCE_CREATE_SIGNALED_BIT;
+
+    fBackbuffers = new BackbufferInfo[fImageCount + 1];
+    for (uint32_t i = 0; i < fImageCount + 1; ++i) {
+        fBackbuffers[i].fImageIndex = -1;
+        GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                            CreateSemaphore(fBackendContext->fDevice, &semaphoreInfo,
+                                            nullptr, &fBackbuffers[i].fAcquireSemaphore));
+        GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                            CreateSemaphore(fBackendContext->fDevice, &semaphoreInfo,
+                                            nullptr, &fBackbuffers[i].fRenderSemaphore));
+        GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                            AllocateCommandBuffers(fBackendContext->fDevice, &commandBuffersInfo,
+                                                   fBackbuffers[i].fTransitionCmdBuffers));
+        GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                            CreateFence(fBackendContext->fDevice, &fenceInfo, nullptr,
+                                        &fBackbuffers[i].fUsageFences[0]));
+        GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                            CreateFence(fBackendContext->fDevice, &fenceInfo, nullptr,
+                                        &fBackbuffers[i].fUsageFences[1]));
+    }
+    fCurrentBackbufferIndex = fImageCount;
+}
+
+void VulkanTestContext::destroyBuffers() {
+
+    if (fBackbuffers) {
+        for (uint32_t i = 0; i < fImageCount + 1; ++i) {
+            GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                                WaitForFences(fBackendContext->fDevice, 2, 
+                                              fBackbuffers[i].fUsageFences,
+                                true, UINT64_MAX));
+            fBackbuffers[i].fImageIndex = -1;
+            GR_VK_CALL(fBackendContext->fInterface,
+                       DestroySemaphore(fBackendContext->fDevice,
+                                        fBackbuffers[i].fAcquireSemaphore,
+                                        nullptr));
+            GR_VK_CALL(fBackendContext->fInterface,
+                       DestroySemaphore(fBackendContext->fDevice,
+                                        fBackbuffers[i].fRenderSemaphore,
+                                        nullptr));
+            GR_VK_CALL(fBackendContext->fInterface,
+                       FreeCommandBuffers(fBackendContext->fDevice, fCommandPool, 2,
+                                          fBackbuffers[i].fTransitionCmdBuffers));
+            GR_VK_CALL(fBackendContext->fInterface,
+                       DestroyFence(fBackendContext->fDevice, fBackbuffers[i].fUsageFences[0], 0));
+            GR_VK_CALL(fBackendContext->fInterface,
+                       DestroyFence(fBackendContext->fDevice, fBackbuffers[i].fUsageFences[1], 0));
+        }
+    }
+
+    delete[] fBackbuffers;
+    fBackbuffers = nullptr;
+
+    delete[] fSurfaces;   //*** will this unref properly?
+    fSurfaces = nullptr;
+    delete[] fImageLayouts;
+    fImageLayouts = nullptr;
+    delete[] fImages;
+    fImages = nullptr;
+}
+
+VulkanTestContext::~VulkanTestContext() {
+    this->destroyContext();
+}
+
+void VulkanTestContext::destroyContext() {
+    if (!fBackendContext.get()) {
+        return;
+    }
+
+    GR_VK_CALL(fBackendContext->fInterface, DeviceWaitIdle(fBackendContext->fDevice));
+
+    this->destroyBuffers();
+
+    if (VK_NULL_HANDLE != fCommandPool) {
+        GR_VK_CALL(fBackendContext->fInterface, DestroyCommandPool(fBackendContext->fDevice,
+                                                                   fCommandPool, nullptr));
+        fCommandPool = VK_NULL_HANDLE;
+    }
+
+    if (VK_NULL_HANDLE != fSwapchain) {
+        GR_VK_CALL(fBackendContext->fInterface, DestroySwapchainKHR(fBackendContext->fDevice,
+                                                                    fSwapchain, nullptr));
+        fSwapchain = VK_NULL_HANDLE;
+    }
+
+    if (VK_NULL_HANDLE != fSurface) {
+        GR_VK_CALL(fBackendContext->fInterface, DestroySurfaceKHR(fBackendContext->fInstance,
+                                                                  fSurface, nullptr));
+        fSurface = VK_NULL_HANDLE;
+    }
+
+    delete fContext;
+
+    fBackendContext.reset(nullptr);
+}
+
+VulkanTestContext::BackbufferInfo* VulkanTestContext::getAvailableBackbuffer() {
+    SkASSERT(fBackbuffers);
+
+    ++fCurrentBackbufferIndex;
+    if (fCurrentBackbufferIndex > fImageCount) {
+        fCurrentBackbufferIndex = 0;
+    }
+
+    BackbufferInfo* backbuffer = fBackbuffers + fCurrentBackbufferIndex;
+
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        WaitForFences(fBackendContext->fDevice, 2, backbuffer->fUsageFences,
+                                      true, UINT64_MAX));
+    return backbuffer;
+}
+
+SkSurface* VulkanTestContext::getBackbufferSurface() {
+    BackbufferInfo* backbuffer = this->getAvailableBackbuffer();
+    SkASSERT(backbuffer);
+
+    // reset the fence
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        ResetFences(fBackendContext->fDevice, 2, backbuffer->fUsageFences));
+    // semaphores should be in unsignaled state
+
+    // acquire the image
+    VkResult res = GR_VK_CALL(fBackendContext->fInterface,
+                              AcquireNextImageKHR(fBackendContext->fDevice, 
+                                                  fSwapchain,
+                                                  UINT64_MAX,
+                                                  backbuffer->fAcquireSemaphore,
+                                                  VK_NULL_HANDLE,
+                                                  &backbuffer->fImageIndex));
+    if (VK_ERROR_SURFACE_LOST_KHR == res) {
+        // need to figure out how to create a new vkSurface without the platformData*
+        return nullptr;
+    }
+    if (VK_ERROR_OUT_OF_DATE_KHR == res || VK_ERROR_SURFACE_LOST_KHR == res) {
+        // tear swapchain down and try again
+        if (!this->createSwapchain(0, 0)) {
+            return nullptr;
+        }
+
+        // acquire the image
+        res = GR_VK_CALL(fBackendContext->fInterface,
+                         AcquireNextImageKHR(fBackendContext->fDevice,
+                                             fSwapchain,
+                                             UINT64_MAX,
+                                             backbuffer->fAcquireSemaphore,
+                                             VK_NULL_HANDLE,
+                                             &backbuffer->fImageIndex));
+
+        if (VK_SUCCESS != res) {
+            return nullptr;
+        }
+    }
+
+    // set up layout transfer from initial to color attachment
+    VkImageLayout layout = fImageLayouts[backbuffer->fImageIndex];
+    VkPipelineStageFlags srcStageMask = GrVkMemory::LayoutToPipelineStageFlags(layout);
+    VkPipelineStageFlags dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+    VkAccessFlags srcAccessMask = GrVkMemory::LayoutToSrcAccessMask(layout);
+    VkAccessFlags dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+
+    VkImageMemoryBarrier imageMemoryBarrier = {
+        VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,   // sType
+        NULL,                                     // pNext
+        srcAccessMask,                            // outputMask
+        dstAccessMask,                            // inputMask
+        layout,                                   // oldLayout
+        VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL, // newLayout
+        fPresentQueueIndex,                       // srcQueueFamilyIndex
+        fBackendContext->fQueueFamilyIndex,       // dstQueueFamilyIndex
+        fImages[backbuffer->fImageIndex],         // image
+        { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 } // subresourceRange
+    };
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        ResetCommandBuffer(backbuffer->fTransitionCmdBuffers[0], 0));
+    VkCommandBufferBeginInfo info;
+    memset(&info, 0, sizeof(VkCommandBufferBeginInfo));
+    info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
+    info.flags = 0;
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        BeginCommandBuffer(backbuffer->fTransitionCmdBuffers[0], &info));
+
+    GR_VK_CALL(fBackendContext->fInterface, 
+                CmdPipelineBarrier(backbuffer->fTransitionCmdBuffers[0], 
+                                    srcStageMask, dstStageMask, 0,
+                                    0, nullptr,
+                                    0, nullptr,
+                                    1, &imageMemoryBarrier));
+
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        EndCommandBuffer(backbuffer->fTransitionCmdBuffers[0]));  
+
+    // insert the layout transfer into the queue and wait on the acquire
+    VkSubmitInfo submitInfo;
+    memset(&submitInfo, 0, sizeof(VkSubmitInfo));
+    submitInfo.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
+    submitInfo.waitSemaphoreCount = 1;
+    submitInfo.pWaitSemaphores = &backbuffer->fAcquireSemaphore;
+    submitInfo.pWaitDstStageMask = 0;
+    submitInfo.commandBufferCount = 1;
+    submitInfo.pCommandBuffers = &backbuffer->fTransitionCmdBuffers[0];
+    submitInfo.signalSemaphoreCount = 0;
+    
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        QueueSubmit(fBackendContext->fQueue, 1, &submitInfo, 
+                                    backbuffer->fUsageFences[0]));
+
+    return fSurfaces[backbuffer->fImageIndex].get();
+}
+
+
+void VulkanTestContext::swapBuffers() {
+
+    BackbufferInfo* backbuffer = fBackbuffers + fCurrentBackbufferIndex;
+
+    VkImageLayout layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+    VkPipelineStageFlags srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+    VkPipelineStageFlags dstStageMask = VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT;
+    VkAccessFlags srcAccessMask = GrVkMemory::LayoutToSrcAccessMask(layout);
+    VkAccessFlags dstAccessMask = VK_ACCESS_MEMORY_READ_BIT;
+
+    VkImageMemoryBarrier imageMemoryBarrier = {
+        VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,   // sType
+        NULL,                                     // pNext
+        srcAccessMask,                            // outputMask
+        dstAccessMask,                            // inputMask
+        layout,                                   // oldLayout
+        VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,          // newLayout
+        fBackendContext->fQueueFamilyIndex,       // srcQueueFamilyIndex
+        fPresentQueueIndex,                       // dstQueueFamilyIndex
+        fImages[backbuffer->fImageIndex],         // image
+        { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 } // subresourceRange
+    };
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        ResetCommandBuffer(backbuffer->fTransitionCmdBuffers[1], 0));
+    VkCommandBufferBeginInfo info;
+    memset(&info, 0, sizeof(VkCommandBufferBeginInfo));
+    info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
+    info.flags = 0;
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        BeginCommandBuffer(backbuffer->fTransitionCmdBuffers[1], &info));
+    GR_VK_CALL(fBackendContext->fInterface,
+                CmdPipelineBarrier(backbuffer->fTransitionCmdBuffers[1],
+                srcStageMask, dstStageMask, 0,
+                0, nullptr,
+                0, nullptr,
+                1, &imageMemoryBarrier));
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        EndCommandBuffer(backbuffer->fTransitionCmdBuffers[1]));
+
+    fImageLayouts[backbuffer->fImageIndex] = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;
+
+    // insert the layout transfer into the queue and wait on the acquire
+    VkSubmitInfo submitInfo;
+    memset(&submitInfo, 0, sizeof(VkSubmitInfo));
+    submitInfo.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
+    submitInfo.waitSemaphoreCount = 0;
+    submitInfo.pWaitDstStageMask = 0;
+    submitInfo.commandBufferCount = 1;
+    submitInfo.pCommandBuffers = &backbuffer->fTransitionCmdBuffers[1];
+    submitInfo.signalSemaphoreCount = 1;
+    submitInfo.pSignalSemaphores = &backbuffer->fRenderSemaphore;
+
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        QueueSubmit(fBackendContext->fQueue, 1, &submitInfo, 
+                                    backbuffer->fUsageFences[1]));
+
+    // Submit present operation to present queue
+    const VkPresentInfoKHR presentInfo =
+    {
+        VK_STRUCTURE_TYPE_PRESENT_INFO_KHR, // sType
+        NULL, // pNext
+        1, // waitSemaphoreCount
+        &backbuffer->fRenderSemaphore, // pWaitSemaphores
+        1, // swapchainCount
+        &fSwapchain, // pSwapchains
+        &backbuffer->fImageIndex, // pImageIndices
+        NULL // pResults
+    };
+
+    GR_VK_CALL_ERRCHECK(fBackendContext->fInterface,
+                        QueuePresentKHR(fPresentQueue, &presentInfo));
+
+}