From 11bf9ad9ee6a23c3202d1a0a6aad35d0a9645494 Mon Sep 17 00:00:00 2001
From: Jesse Natalie <jenatali@microsoft.com>
Date: Mon, 25 Aug 2025 14:52:40 -0700
Subject: [PATCH] d3d12: Only use DComp swapchains when alpha is present in the
 framebuffer

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36994>
---
 .../d3d12/wgl/d3d12_wgl_framebuffer.cpp       | 49 ++++++++++++-------
 1 file changed, 32 insertions(+), 17 deletions(-)

diff --git a/src/gallium/winsys/d3d12/wgl/d3d12_wgl_framebuffer.cpp b/src/gallium/winsys/d3d12/wgl/d3d12_wgl_framebuffer.cpp
index 31917eb359b..8f239d90292 100644
--- a/src/gallium/winsys/d3d12/wgl/d3d12_wgl_framebuffer.cpp
+++ b/src/gallium/winsys/d3d12/wgl/d3d12_wgl_framebuffer.cpp
@@ -179,30 +179,45 @@ d3d12_wgl_framebuffer_resize(stw_winsys_framebuffer *fb,
       break;
    }
 
-   if (!framebuffer->dcomp) {
-      framebuffer->dcomp.Attach(dcomp_get_device());
+   if (desc.AlphaMode != DXGI_ALPHA_MODE_IGNORE) {
       if (!framebuffer->dcomp) {
-         debug_printf("D3D12: failed to create dcomp device\n");
-         return;
+         framebuffer->dcomp.Attach(dcomp_get_device());
+         if (!framebuffer->dcomp) {
+            debug_printf("D3D12: failed to create dcomp device\n");
+            return;
+         }
       }
-   }
 
-   if (!framebuffer->target) {
-      if (FAILED(framebuffer->dcomp->CreateTargetForHwnd(framebuffer->window, TRUE, &framebuffer->target))) {
-         debug_printf("D3D12: failed to create dcomp target\n");
-         return;
+      if (!framebuffer->target) {
+         if (FAILED(framebuffer->dcomp->CreateTargetForHwnd(framebuffer->window, TRUE, &framebuffer->target))) {
+            debug_printf("D3D12: failed to create dcomp target\n");
+            return;
+         }
       }
    }
 
    if (!framebuffer->swapchain) {
       ComPtr<IDXGISwapChain1> swapchain1;
-      if (FAILED(screen->factory->CreateSwapChainForComposition(
-         screen->base.cmdqueue,
-         &desc,
-         nullptr,
-         &swapchain1))) {
-         debug_printf("D3D12: failed to create swapchain\n");
-         return;
+      if (desc.AlphaMode != DXGI_ALPHA_MODE_IGNORE) {
+         if (FAILED(screen->factory->CreateSwapChainForComposition(
+            screen->base.cmdqueue,
+            &desc,
+            nullptr,
+            &swapchain1))) {
+            debug_printf("D3D12: failed to create swapchain\n");
+            return;
+         }
+      } else {
+         if (FAILED(screen->factory->CreateSwapChainForHwnd(
+            screen->base.cmdqueue,
+            framebuffer->window,
+            &desc,
+            nullptr,
+            nullptr,
+            &swapchain1))) {
+            debug_printf("D3D12: failed to create swapchain\n");
+            return;
+         }
       }
 
       swapchain1.As(&framebuffer->swapchain);
@@ -235,7 +250,7 @@ d3d12_wgl_framebuffer_resize(stw_winsys_framebuffer *fb,
       }
    }
 
-   if (!framebuffer->visual) {
+   if (!framebuffer->visual && desc.AlphaMode != DXGI_ALPHA_MODE_IGNORE) {
       if (FAILED(framebuffer->dcomp->CreateVisual(&framebuffer->visual)) ||
           FAILED(framebuffer->target->SetRoot(framebuffer->visual.Get())) ||
           FAILED(framebuffer->visual->SetContent(framebuffer->swapchain.Get())) ||