From 3316003e3a8746b4abe65a99b516395eb82cae47 Mon Sep 17 00:00:00 2001
From: Ravbug <ravbuganimations@gmail.com>
Date: Sun, 15 Oct 2023 22:28:49 -0400
Subject: [PATCH] D3D12, Vk: API to toggle vsync via the swapchain

---
 include/RGL/Swapchain.hpp |  2 ++
 src/D3D12Swapchain.cpp    |  4 ++++
 src/D3D12Swapchain.hpp    |  4 +++-
 src/VkSwapchain.cpp       | 28 ++++++++++++++++++++++------
 src/VkSwapchain.hpp       |  3 +++
 5 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/include/RGL/Swapchain.hpp b/include/RGL/Swapchain.hpp
index 4c854db..cecf877 100644
--- a/include/RGL/Swapchain.hpp
+++ b/include/RGL/Swapchain.hpp
@@ -14,5 +14,7 @@ namespace RGL{
 		virtual void GetNextImage(uint32_t* index) = 0;
 		virtual ITexture* ImageAtIndex(uint32_t index) = 0;
 		virtual void Present(const SwapchainPresentConfig&) = 0;
+
+		virtual void SetVsyncMode(bool mode) = 0;
 	};
 }
diff --git a/src/D3D12Swapchain.cpp b/src/D3D12Swapchain.cpp
index a2d05d7..1a1344c 100644
--- a/src/D3D12Swapchain.cpp
+++ b/src/D3D12Swapchain.cpp
@@ -193,6 +193,10 @@ namespace RGL {
         UINT presentFlags = (tearingSupported && !vsync) ? DXGI_PRESENT_ALLOW_TEARING : 0;
         swapchain->Present(syncInterval, presentFlags);
 	}
+    void SwapchainD3D12::SetVsyncMode(bool mode)
+    {
+        vsync = mode;
+    }
     SwapchainD3D12::~SwapchainD3D12()
     {
     }
diff --git a/src/D3D12Swapchain.hpp b/src/D3D12Swapchain.hpp
index b9730dc..d3d5057 100644
--- a/src/D3D12Swapchain.hpp
+++ b/src/D3D12Swapchain.hpp
@@ -23,7 +23,6 @@ namespace RGL {
 		D3D12DynamicDescriptorHeap::index_t rtvIndices[g_NumFrames];
 
 		bool tearingSupported = false;
-		bool vsync = true;
 		bool initialized = false;
 
 		SwapchainD3D12(decltype(owningDevice), std::shared_ptr<SurfaceD3D12>, int width, int height, std::shared_ptr<CommandQueueD3D12> presentQueue);
@@ -37,6 +36,9 @@ namespace RGL {
 		void GetNextImage(uint32_t* index) final;
 		ITexture* ImageAtIndex(uint32_t index) final;
 		void Present(const SwapchainPresentConfig&) final;
+		void SetVsyncMode(bool mode) final;
 		virtual ~SwapchainD3D12();
+	private:
+		bool vsync = true;
 	};
 }
\ No newline at end of file
diff --git a/src/VkSwapchain.cpp b/src/VkSwapchain.cpp
index 2c6d453..004df2c 100644
--- a/src/VkSwapchain.cpp
+++ b/src/VkSwapchain.cpp
@@ -40,14 +40,22 @@ void RGL::SwapchainVK::Resize(uint32_t width, uint32_t height)
         //otherwise hope the first one is good enough
         return availableFormats[0];
     };
-    constexpr auto chooseSwapPresentMode = [](const std::vector<VkPresentModeKHR>& availablePresentModes) -> VkPresentModeKHR {
-        for (const auto& availablePresentMode : availablePresentModes) {
-            if (availablePresentMode == VK_PRESENT_MODE_MAILBOX_KHR) {
-                return availablePresentMode;    // use Mailbox on high-perf devices
+    auto chooseSwapPresentMode = [this](const std::vector<VkPresentModeKHR>& availablePresentModes) -> VkPresentModeKHR {
+        if (vsync) {
+            // disabling this because apparently VK_PRESENT_MODE_MAILBOX_KHR is uncapped on some OS/driver combos
+#if 0
+            for (const auto& availablePresentMode : availablePresentModes) {
+                if (availablePresentMode == VK_PRESENT_MODE_MAILBOX_KHR) {
+                    return availablePresentMode;    // use Mailbox on high-perf devices
+                }
             }
-        }
+#endif
 
-        return VK_PRESENT_MODE_FIFO_KHR;        // otherwise use FIFO when on low-power devices, like a mobile phone
+            return VK_PRESENT_MODE_FIFO_KHR;        // otherwise use FIFO when on low-power devices, like a mobile phone
+        }
+        else {
+            return VK_PRESENT_MODE_IMMEDIATE_KHR;
+        }
     };
     auto chooseSwapExtent = [width,height](const VkSurfaceCapabilitiesKHR& capabilities) ->VkExtent2D {
         if (capabilities.currentExtent.width != std::numeric_limits<uint32_t>::max()) {
@@ -181,6 +189,14 @@ void RGL::SwapchainVK::Present(const SwapchainPresentConfig& config)
     }
 }
 
+void RGL::SwapchainVK::SetVsyncMode(bool mode)
+{
+    vsync = mode;
+    auto size = RGLTextureResources[0].GetSize();
+    // re-create with the new queue present mode
+    Resize(size.width, size.height);
+}
+
 
 void RGL::SwapchainVK::DestroySwapchainIfNeeded()
 {
diff --git a/src/VkSwapchain.hpp b/src/VkSwapchain.hpp
index 153c282..f9f3d8c 100644
--- a/src/VkSwapchain.hpp
+++ b/src/VkSwapchain.hpp
@@ -28,7 +28,10 @@ namespace RGL {
 
 		void Present(const SwapchainPresentConfig&) final;
 
+		void SetVsyncMode(bool mode) final;
+
 	private:
+		bool vsync = true;
 		void DestroySwapchainIfNeeded();
 	};
 }
\ No newline at end of file