From 792500bd1b259f0e8013055a5a5462ff3ff0cd76 Mon Sep 17 00:00:00 2001
From: Piero Toffanin <pt@masseranolabs.com>
Date: Wed, 24 Nov 2021 11:26:03 -0500
Subject: [PATCH] Use dummy CUDA DLL

---
 SuperBuild/cmake/External-OpenMVS.cmake | 10 ++++++----
 opendm/gpu.py                           |  1 +
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/SuperBuild/cmake/External-OpenMVS.cmake b/SuperBuild/cmake/External-OpenMVS.cmake
index dd42604b..80b4585a 100644
--- a/SuperBuild/cmake/External-OpenMVS.cmake
+++ b/SuperBuild/cmake/External-OpenMVS.cmake
@@ -36,10 +36,12 @@ if(UNIX)
 endif()
 
 if(WIN32)
-  SET(NVDRIVER "$ENV{SystemRoot}\\System32\\nvcuda.dll")
-  if (EXISTS ${NVDRIVER})
-    file(COPY ${NVDRIVER} DESTINATION "${SB_INSTALL_DIR}/bin")
-  endif()
+  # On Windows systems without NVIDIA GPUs, OpenMVS will not launch
+  # unless a CUDA DLL is available; we download a dummy DLL 
+  # generated with https://github.com/ykhwong/dummy-dll-generator that is 
+  # loaded UNLESS the real CUDA DLL is available, since it will
+  # be loaded before our dummy DLL.
+  file(DOWNLOAD "https://github.com/OpenDroneMap/windows-deps/releases/download/2.5.0/nvcuda_dummy.dll" "${SB_INSTALL_DIR}/bin/nvcuda.dll")
 endif()
 
 ExternalProject_Add(${_proj_name}
diff --git a/opendm/gpu.py b/opendm/gpu.py
index 81014fcd..53f7d1a9 100644
--- a/opendm/gpu.py
+++ b/opendm/gpu.py
@@ -1,4 +1,5 @@
 import os
+import sys
 from opendm import log
 from repoze.lru import lru_cache