Vulkan backend: g_FrameIndex not used fix -> huge perf gain
Added a macro to switch between unlimited frame rate (VK_PRESENT_MODE_IMMEDIATE_KHR) and limited to 60 fps (VK_PRESENT_MODE_FIFO_KHR). Only the latter mode is guaranteed to be available, but the former one most likely is.
diff --git a/examples/vulkan_example/main.cpp b/examples/vulkan_example/main.cpp
index 8116e08..265ec80 100644
--- a/examples/vulkan_example/main.cpp
+++ b/examples/vulkan_example/main.cpp
@@ -12,6 +12,7 @@
#include "imgui_impl_glfw_vulkan.h"
#define IMGUI_MAX_POSSIBLE_BACK_BUFFERS 16
+#define IMGUI_UNLIMITED_FRAME_RATE
static VkAllocationCallbacks* g_Allocator = NULL;
static VkInstance g_Instance = VK_NULL_HANDLE;
@@ -83,7 +84,12 @@
info.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;
info.preTransform = VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR;
info.compositeAlpha = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
+
+#ifdef IMGUI_UNLIMITED_FRAME_RATE
+ info.presentMode = VK_PRESENT_MODE_IMMEDIATE_KHR;
+#elif
info.presentMode = VK_PRESENT_MODE_FIFO_KHR;
+#endif
info.clipped = VK_TRUE;
info.oldSwapchain = old_swapchain;
VkSurfaceCapabilitiesKHR cap;
@@ -93,6 +99,7 @@
info.minImageCount = (cap.minImageCount + 2 < cap.maxImageCount) ? (cap.minImageCount + 2) : cap.maxImageCount;
else
info.minImageCount = cap.minImageCount + 2;
+
if (cap.currentExtent.width == 0xffffffff)
{
fb_width = w;
@@ -462,7 +469,7 @@
check_vk_result(err);
check_vk_result(res);
}
- g_FrameIndex = (g_FrameIndex) % IMGUI_VK_QUEUED_FRAMES;
+ g_FrameIndex = (g_FrameIndex+1) % IMGUI_VK_QUEUED_FRAMES;
}
static void error_callback(int error, const char* description)
