allow suboptimal rendering with fewer than required swapchain images

fixes #61

include/layer.hpp

@@ -53,6 +53,11 @@ namespace Layer {
     void ovkGetPhysicalDeviceProperties(
         VkPhysicalDevice physicalDevice,
         VkPhysicalDeviceProperties* pProperties);
+    /// Call to the original vkGetPhysicalDeviceSurfaceCapabilitiesKHR function.
+    VkResult ovkGetPhysicalDeviceSurfaceCapabilitiesKHR(
+        VkPhysicalDevice physicalDevice,
+        VkSurfaceKHR surface,
+        VkSurfaceCapabilitiesKHR* pSurfaceCapabilities);
 
     /// Call to the original vkCreateSwapchainKHR function.
     VkResult ovkCreateSwapchainKHR(

include/utils/utils.hpp

@@ -31,6 +31,15 @@ namespace Utils {
     ///
     uint64_t getDeviceUUID(VkPhysicalDevice physicalDevice);
 
+    ///
+    /// Get the max image count for a swapchain.
+    ///
+    /// @param physicalDevice The physical device to query.
+    /// @param surface The surface to query the capabilities for.
+    /// @return The maximum image count for the swapchain.
+    ///
+    uint32_t getMaxImageCount(VkPhysicalDevice physicalDevice, VkSurfaceKHR surface);
+
     ///
     /// Ensure a list of extensions is present in the given array.
     ///

src/hooks.cpp

@@ -151,13 +151,21 @@ namespace {
 
         // update swapchain create info
         VkSwapchainCreateInfoKHR createInfo = *pCreateInfo;
-        createInfo.minImageCount += 1 + deviceInfo.frameGen; // 1 deferred + N framegen, FIXME: check hardware max
+        const uint32_t maxImageCount = Utils::getMaxImageCount(deviceInfo.physicalDevice, pCreateInfo->surface);
+        const uint32_t imageCount = createInfo.minImageCount + 1 + static_cast<uint32_t>(deviceInfo.frameGen);
+        Log::debug("hooks", "Creating swapchain with max image count: {}/{}", imageCount, maxImageCount);
+        if (imageCount > maxImageCount) {
+            Log::warn("hooks", "LSFG_MULTIPLIER is set very high. This might lead to performance degradation");
+            createInfo.minImageCount = maxImageCount; // limit to max possible
+        } else {
+            createInfo.minImageCount = imageCount; // set to frameGen + 1
+        }
         createInfo.imageUsage |= VK_IMAGE_USAGE_TRANSFER_DST_BIT; // allow copy from/to images
         createInfo.imageUsage |= VK_IMAGE_USAGE_TRANSFER_SRC_BIT;
         createInfo.presentMode = VK_PRESENT_MODE_FIFO_KHR; // force vsync
         auto res = Layer::ovkCreateSwapchainKHR(device, &createInfo, pAllocator, pSwapchain);
         if (res != VK_SUCCESS) {
-            Log::error("hooks", "Failed to create swapchain: {:x}", static_cast<uint32_t>(res));
+            Log::error("hooks", "Failed to create swapchain: {}", static_cast<uint32_t>(res));
             return res;
         }
         Log::info("hooks", "Swapchain created successfully: {:x}",
@@ -235,6 +243,8 @@ namespace {
         auto& swapchain = it3->second;
 
         // patch vsync NOLINTBEGIN
+        #pragma clang diagnostic push
+        #pragma clang diagnostic ignored "-Wunsafe-buffer-usage"
         const VkSwapchainPresentModeInfoEXT* presentModeInfo =
             reinterpret_cast<const VkSwapchainPresentModeInfoEXT*>(pPresentInfo->pNext);
         while (presentModeInfo) {
@@ -246,6 +256,7 @@ namespace {
             presentModeInfo =
                 reinterpret_cast<const VkSwapchainPresentModeInfoEXT*>(presentModeInfo->pNext);
         } // NOLINTEND
+#pragma clang diagnostic pop
 
         // present the next frame
         Log::debug("hooks2", "Presenting swapchain: {:x} on queue: {:x}",

src/layer.cpp

@@ -23,6 +23,7 @@ namespace {
     PFN_vkGetPhysicalDeviceQueueFamilyProperties next_vkGetPhysicalDeviceQueueFamilyProperties{};
     PFN_vkGetPhysicalDeviceMemoryProperties next_vkGetPhysicalDeviceMemoryProperties{};
     PFN_vkGetPhysicalDeviceProperties next_vkGetPhysicalDeviceProperties{};
+    PFN_vkGetPhysicalDeviceSurfaceCapabilitiesKHR next_vkGetPhysicalDeviceSurfaceCapabilitiesKHR{};
 
     PFN_vkCreateSwapchainKHR  next_vkCreateSwapchainKHR{};
     PFN_vkQueuePresentKHR     next_vkQueuePresentKHR{};
@@ -122,6 +123,8 @@ namespace {
             "vkGetPhysicalDeviceMemoryProperties", &next_vkGetPhysicalDeviceMemoryProperties);
         success &= initInstanceFunc(*pInstance,
             "vkGetPhysicalDeviceProperties", &next_vkGetPhysicalDeviceProperties);
+        success &= initInstanceFunc(*pInstance,
+            "vkGetPhysicalDeviceSurfaceCapabilitiesKHR", &next_vkGetPhysicalDeviceSurfaceCapabilitiesKHR);
         if (!success) {
             Log::error("layer", "Failed to get instance function pointers");
             return VK_ERROR_INITIALIZATION_FAILED;
@@ -374,6 +377,15 @@ void Layer::ovkGetPhysicalDeviceProperties(
         reinterpret_cast<uintptr_t>(physicalDevice));
     next_vkGetPhysicalDeviceProperties(physicalDevice, pProperties);
 }
+VkResult Layer::ovkGetPhysicalDeviceSurfaceCapabilitiesKHR(
+        VkPhysicalDevice physicalDevice,
+        VkSurfaceKHR surface,
+        VkSurfaceCapabilitiesKHR* pSurfaceCapabilities) {
+    Log::debug("vulkan", "vkGetPhysicalDeviceSurfaceCapabilitiesKHR called for physical device {:x} and surface {:x}",
+        reinterpret_cast<uintptr_t>(physicalDevice),
+        reinterpret_cast<uintptr_t>(surface));
+    return next_vkGetPhysicalDeviceSurfaceCapabilitiesKHR(physicalDevice, surface, pSurfaceCapabilities);
+}
 
 VkResult Layer::ovkCreateSwapchainKHR(
         VkDevice device,

src/utils/utils.cpp

@@ -53,6 +53,17 @@ uint64_t Utils::getDeviceUUID(VkPhysicalDevice physicalDevice) {
     return static_cast<uint64_t>(properties.vendorID) << 32 | properties.deviceID;
 }
 
+uint32_t Utils::getMaxImageCount(VkPhysicalDevice physicalDevice, VkSurfaceKHR surface) {
+    VkSurfaceCapabilitiesKHR capabilities{};
+    auto res = Layer::ovkGetPhysicalDeviceSurfaceCapabilitiesKHR(physicalDevice,
+        surface, &capabilities);
+    if (res != VK_SUCCESS)
+        throw LSFG::vulkan_error(res, "Failed to get surface capabilities");
+    if (capabilities.maxImageCount == 0)
+        return 999; // :3
+    return capabilities.maxImageCount;
+}
+
 std::vector<const char*> Utils::addExtensions(const char* const* extensions, size_t count,
         const std::vector<const char*>& requiredExtensions) {
     std::vector<const char*> ext(count);