SDL: vulkan gpu: set the sample count for depth prepass

SDL Commits
1 
From 1fc093491ac6a0c53b3ee36ea50dc835869acf09 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Sat, 22 Nov 2025 07:53:16 -0800
Subject: [PATCH] vulkan gpu: set the sample count for depth prepass

Fixes https://github.com/libsdl-org/SDL/issues/14500
---
 src/gpu/vulkan/SDL_gpu_vulkan.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/gpu/vulkan/SDL_gpu_vulkan.c b/src/gpu/vulkan/SDL_gpu_vulkan.c
index c0e64ebf24b10..e4e34a2f0d5b4 100644
--- a/src/gpu/vulkan/SDL_gpu_vulkan.c
+++ b/src/gpu/vulkan/SDL_gpu_vulkan.c
@@ -7189,6 +7189,8 @@ static VkRenderPass VULKAN_INTERNAL_FetchRenderPass(
     key.sampleCount = VK_SAMPLE_COUNT_1_BIT;
     if (numColorTargets > 0) {
         key.sampleCount = SDLToVK_SampleCount[((VulkanTextureContainer *)colorTargetInfos[0].texture)->header.info.sample_count];
+    } else if (numColorTargets == 0 && depthStencilTargetInfo != NULL) {
+        key.sampleCount = SDLToVK_SampleCount[((VulkanTextureContainer *)depthStencilTargetInfo->texture)->header.info.sample_count];
     }
 
     key.numColorTargets = numColorTargets;