From 439e2b43c33f48fe380d8c43c39836ec9a96064b Mon Sep 17 00:00:00 2001
From: James Ross-Gowan <rossymiles@gmail.com>
Date: Sun, 26 Mar 2017 01:49:19 +1100
Subject: vo_opengl: angle: add --angle-flip to set the present model

DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL might be buggy on some hardware.
Additionaly DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL might be supported on some
Windows 7 systems with the platform update, but it might have poor
performance. In these cases, the user might want to disable the use of
DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL swap chains with --angle-flip=no.
---
 DOCS/man/options.rst             | 17 +++++++++++++++--
 video/out/opengl/context_angle.c | 30 ++++++++++++++++++++++++++++--
 2 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/DOCS/man/options.rst b/DOCS/man/options.rst
index a50ae8a3cf..19e331a468 100644
--- a/DOCS/man/options.rst
+++ b/DOCS/man/options.rst
@@ -4384,8 +4384,21 @@ The following video options are currently all specific to ``--vo=opengl`` and
     chain will be used for D3D9. This option is mainly for debugging purposes,
     in case the custom swap chain has poor performance or does not work.
 
-    If set to ``yes``, the ``--angle-max-frame-latency`` and
-    ``--angle-swapchain-length`` options will have no effect.
+    If set to ``yes``, the ``--angle-max-frame-latency``,
+    ``--angle-swapchain-length`` and ``--angle-flip`` options will have no
+    effect.
+
+    Windows with ANGLE only.
+
+``--angle-flip=<yes|no>``
+    Enable flip-model presentation, which avoids unnecessarily copying the
+    backbuffer by sharing surfaces with the DWM (default: yes). This may cause
+    performance issues with older drivers. If flip-model presentation is not
+    supported (for example, on Windows 7 without the platform update), mpv will
+    automatically fall back to the older bitblt presentation model.
+
+    If set to ``no``, the ``--angle-swapchain-length`` option will have no
+    effect.
 
     Windows with ANGLE only.
 
diff --git a/video/out/opengl/context_angle.c b/video/out/opengl/context_angle.c
index 7a011a80a4..062835da30 100644
--- a/video/out/opengl/context_angle.c
+++ b/video/out/opengl/context_angle.c
@@ -56,6 +56,7 @@ struct angle_opts {
     int egl_windowing;
     int swapchain_length; // Currently only works with DXGI 1.2+
     int max_frame_latency;
+    int flip;
 };
 
 #define OPT_BASE_STRUCT struct angle_opts
@@ -80,6 +81,7 @@ const struct m_sub_options angle_conf = {
                     {"yes", 1})),
         OPT_INTRANGE("angle-swapchain-length", swapchain_length, 0, 2, 16),
         OPT_INTRANGE("angle-max-frame-latency", max_frame_latency, 0, 1, 16),
+        OPT_FLAG("angle-flip", flip, 0),
         {0}
     },
     .defaults = &(const struct angle_opts) {
@@ -89,6 +91,7 @@ const struct m_sub_options angle_conf = {
         .egl_windowing = -1,
         .swapchain_length = 6,
         .max_frame_latency = 3,
+        .flip = 1,
     },
     .size = sizeof(struct angle_opts),
 };
@@ -383,13 +386,28 @@ static bool d3d11_swapchain_create_1_2(MPGLContext *ctx, int flags)
         .SampleDesc = { .Count = 1 },
         .BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT |
                        DXGI_USAGE_SHADER_INPUT,
-        .BufferCount = p->opts->swapchain_length,
-        .SwapEffect = DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL,
     };
 
+    if (p->opts->flip) {
+        desc1.SwapEffect = DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL;
+        desc1.BufferCount = p->opts->swapchain_length;
+    } else {
+        desc1.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;
+        desc1.BufferCount = 1;
+    }
+
     hr = IDXGIFactory2_CreateSwapChainForHwnd(p->dxgi_factory2,
         (IUnknown*)p->d3d11_device, vo_w32_hwnd(vo), &desc1, NULL, NULL,
         &p->dxgi_swapchain1);
+    if (FAILED(hr) && p->opts->flip) {
+        // Try again without DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL
+        desc1.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;
+        desc1.BufferCount = 1;
+
+        hr = IDXGIFactory2_CreateSwapChainForHwnd(p->dxgi_factory2,
+            (IUnknown*)p->d3d11_device, vo_w32_hwnd(vo), &desc1, NULL, NULL,
+            &p->dxgi_swapchain1);
+    }
     if (FAILED(hr)) {
         MP_FATAL(vo, "Couldn't create DXGI 1.2+ swap chain: %s\n",
                  mp_HRESULT_to_str(hr));
@@ -670,6 +688,14 @@ static int angle_init(struct MPGLContext *ctx, int flags)
         if (surface_ok) {
             if (p->dxgi_swapchain1) {
                 MP_VERBOSE(vo, "Using DXGI 1.2+\n");
+
+                DXGI_SWAP_CHAIN_DESC1 scd = {0};
+                IDXGISwapChain1_GetDesc1(p->dxgi_swapchain1, &scd);
+                if (scd.SwapEffect == DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL) {
+                    MP_VERBOSE(vo, "Using flip-model presentation\n");
+                } else {
+                    MP_VERBOSE(vo, "Using bitblt-model presentation\n");
+                }
             } else {
                 MP_VERBOSE(vo, "Using DXGI 1.1\n");
             }
-- 
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