From f60fd291b58bc5081f7ed96671207778522fcba1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Antti=20M=C3=A4=C3=A4tt=C3=A4?= <antti.maatta@qt.io>
Date: Mon, 25 Nov 2024 09:23:15 +0200
Subject: [PATCH] Fix creating multisampled pipeline on dx12 backend

Use the depthStencil format to check multisample support when the
pipeline doesn't have color attachments.

Fixes: QTBUG-131505
Change-Id: I8fec8383ed854a581586213e3dbd401bb457cefc
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
(cherry picked from commit f6d67ed9b760e87af3e032ea49e5babc6951ef91)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/gui/rhi/qrhid3d12.cpp | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/gui/rhi/qrhid3d12.cpp b/src/gui/rhi/qrhid3d12.cpp
index b9bb5803579..0bb9760daa8 100644
--- a/src/gui/rhi/qrhid3d12.cpp
+++ b/src/gui/rhi/qrhid3d12.cpp
@@ -5668,7 +5668,16 @@ bool QD3D12GraphicsPipeline::create()
     }
 
     QD3D12RenderPassDescriptor *rpD = QRHI_RES(QD3D12RenderPassDescriptor, m_renderPassDesc);
-    const DXGI_SAMPLE_DESC sampleDesc = rhiD->effectiveSampleDesc(m_sampleCount, DXGI_FORMAT(rpD->colorFormat[0]));
+    DXGI_FORMAT format = DXGI_FORMAT_UNKNOWN;
+    if (rpD->colorAttachmentCount > 0) {
+        format = DXGI_FORMAT(rpD->colorFormat[0]);
+    } else if (rpD->hasDepthStencil) {
+        format = DXGI_FORMAT(rpD->dsFormat);
+    } else {
+        qWarning("Cannot create graphics pipeline state without color or depthStencil format");
+        return false;
+    }
+    const DXGI_SAMPLE_DESC sampleDesc = rhiD->effectiveSampleDesc(m_sampleCount, format);
 
     struct {
         QD3D12PipelineStateSubObject<ID3D12RootSignature *, D3D12_PIPELINE_STATE_SUBOBJECT_TYPE_ROOT_SIGNATURE> rootSig;