SDL: GPU: Update D3D12 to create multisample textures with default MSAA alignment

SDL Commits
1 
From f4942b3eae13f6fe905183457fa5e37cfd09c7d5 Mon Sep 17 00:00:00 2001
From: Logan <[EMAIL REDACTED]>
Date: Tue, 20 May 2025 13:29:42 +1200
Subject: [PATCH] GPU: Update D3D12 to create multisample textures with default
 MSAA alignment

---
 src/gpu/d3d12/SDL_gpu_d3d12.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/gpu/d3d12/SDL_gpu_d3d12.c b/src/gpu/d3d12/SDL_gpu_d3d12.c
index ca170089d9170..4cb8df5c58c06 100644
--- a/src/gpu/d3d12/SDL_gpu_d3d12.c
+++ b/src/gpu/d3d12/SDL_gpu_d3d12.c
@@ -3346,7 +3346,7 @@ static D3D12Texture *D3D12_INTERNAL_CreateTexture(
 
     if (createinfo->type != SDL_GPU_TEXTURETYPE_3D) {
         desc.Dimension = D3D12_RESOURCE_DIMENSION_TEXTURE2D;
-        desc.Alignment = isSwapchainTexture ? 0 : D3D12_DEFAULT_RESOURCE_PLACEMENT_ALIGNMENT;
+        desc.Alignment = isSwapchainTexture ? 0 : isMultisample ? D3D12_DEFAULT_MSAA_RESOURCE_PLACEMENT_ALIGNMENT : D3D12_DEFAULT_RESOURCE_PLACEMENT_ALIGNMENT;
         desc.Width = createinfo->width;
         desc.Height = createinfo->height;
         desc.DepthOrArraySize = (UINT16)createinfo->layer_count_or_depth;