From 1ce1364b29e90af81133c0ddcb4a92d9e81f6b49 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <icculus@icculus.org>
Date: Sat, 26 Oct 2019 12:56:18 -0400
Subject: [PATCH] d3d11: Don't fail if there's no vertex data to upload
 (thanks, Martin!).

Fixes Bugzilla #4832.
---
 src/render/direct3d11/SDL_render_d3d11.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/render/direct3d11/SDL_render_d3d11.c b/src/render/direct3d11/SDL_render_d3d11.c
index d75da715b..720622df4 100644
--- a/src/render/direct3d11/SDL_render_d3d11.c
+++ b/src/render/direct3d11/SDL_render_d3d11.c
@@ -1818,6 +1818,10 @@ D3D11_UpdateVertexBuffer(SDL_Renderer *renderer,
     HRESULT result = S_OK;
     const int vbidx = rendererData->currentVertexBuffer;
 
+    if (dataSizeInBytes == 0) {
+        return 0;  /* nothing to do. */
+    }
+
     if (rendererData->vertexBuffers[vbidx] && rendererData->vertexBufferSizes[vbidx] >= dataSizeInBytes) {
         D3D11_MAPPED_SUBRESOURCE mappedResource;
         result = ID3D11DeviceContext_Map(rendererData->d3dContext,