之前写过的一篇博文：OpenCV使用CMake和MinGW的编译安装及其在Qt配置运行 是使用 32 位的 MinGW 在 Windows 下编译 OpenCV 生成 32 位的 dll。
而这篇博文是使用 64 位的 MinGW 编译 OpenCV 生成 64 位的 dll。
因为博主没有 64 位 qmake，所以没勾选 WITH_QT
Github . huihut/OpenCV-MinGW-Build
下载安装：MinGW-x64-4.8.1-release-posix-seh-rev5
（博文使用 MinGW-x64-4.8.1 为例，但建议使用最新 MinGW：MinGW-w64 - for 32 and 64 bit Windows）
为用户变量 Path 添加 E:\MinGW-w64\x64-4.8.1-release-posix-seh-rev5\mingw64\bin
打开命令提示符 CMD，运行 set PATH=C:，更改当前窗口任务的环境变量，关闭这个 CMD。
再次打开另一个 CMD，运行 echo %PATH%，显示最新的环境变量，会发现刚刚添加的 MinGW 环境变量已经生效。
打开 cmake-gui，设置源码和生成路径：
E:/opencv_341/opencv/sourcesE:/opencv_341/opencv_mingw64_build点击 Configure，设置编译器
MinGW MakefilesE:\MinGW-w64\x64-4.8.1-release-posix-seh-rev5\mingw64\bin\gcc.exeE:\MinGW-w64\x64-4.8.1-release-posix-seh-rev5\mingw64\bin\g++.exe编译配置：
WITH_OPENGLENABLE_CXX11WITH_IPPENABLE_PRECOMPILED_HEADERS点击 Configure，Generate 生成 Makefile
博主的配置信息如下：
General configuration for OpenCV 3.4.1 =====================================
Version control: unknown
Platform:
Timestamp: 2018-07-31T02:14:11Z
Host: Windows 10.0.17134 AMD64
CMake: 3.12.0
CMake generator: MinGW Makefiles
CMake build tool: E:/MinGW-w64/x64-4.8.1-release-posix-seh-rev5/mingw64/bin/mingw32-make.exe
Configuration: Release
CPU/HW features:
Baseline: SSE SSE2 SSE3
requested: SSE3
Dispatched code generation: SSE4_1 SSE4_2 FP16 AVX AVX2
requested: SSE4_1 SSE4_2 AVX FP16 AVX2 AVX512_SKX
SSE4_1 (3 files): + SSSE3 SSE4_1
SSE4_2 (1 files): + SSSE3 SSE4_1 POPCNT SSE4_2
FP16 (2 files): + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 AVX
AVX (5 files): + SSSE3 SSE4_1 POPCNT SSE4_2 AVX
AVX2 (9 files): + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2
C/C++:
Built as dynamic libs?: YES
C++11: YES
C++ Compiler: E:/MinGW-w64/x64-4.8.1-release-posix-seh-rev5/mingw64/bin/g++.exe (ver 4.8.1)
C++ flags (Release): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Winit-self -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -fomit-frame-pointer -ffunction-sections -fdata-sections -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG -DNDEBUG
C++ flags (Debug): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Winit-self -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -fomit-frame-pointer -ffunction-sections -fdata-sections -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -g -O0 -DDEBUG -D_DEBUG
C Compiler: E:/MinGW-w64/x64-4.8.1-release-posix-seh-rev5/mingw64/bin/gcc.exe
C flags (Release): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Winit-self -Wno-narrowing -Wno-comment -fdiagnostics-show-option -Wno-long-long -fomit-frame-pointer -ffunction-sections -fdata-sections -msse -msse2 -msse3 -fvisibility=hidden -O3 -DNDEBUG -DNDEBUG
C flags (Debug): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Winit-self -Wno-narrowing -Wno-comment -fdiagnostics-show-option -Wno-long-long -fomit-frame-pointer -ffunction-sections -fdata-sections -msse -msse2 -msse3 -fvisibility=hidden -g -O0 -DDEBUG -D_DEBUG
Linker flags (Release): -Wl,--gc-sections
Linker flags (Debug): -Wl,--gc-sections
ccache: NO
Precompiled headers: NO
Extra dependencies: opengl32 glu32
3rdparty dependencies:
OpenCV modules:
To be built: calib3d core dnn features2d flann highgui imgcodecs imgproc java_bindings_generator ml objdetect photo python_bindings_generator shape stitching superres ts video videoio videostab
Disabled: js world
Disabled by dependency: -
Unavailable: cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev java python2 python3 viz
Applications: tests perf_tests apps
Documentation: NO
Non-free algorithms: NO
Windows RT support: NO
GUI:
Win32 UI: YES
OpenGL support: YES (opengl32 glu32)
VTK support: NO
Media I/O:
ZLib: build (ver 1.2.11)
JPEG: build (ver 90)
WEBP: build (ver encoder: 0x020e)
PNG: build (ver 1.6.34)
TIFF: build (ver 42 - 4.0.9)
JPEG 2000: build (ver 1.900.1)
OpenEXR: build (ver 1.7.1)
Video I/O:
Video for Windows: YES
DC1394: NO
FFMPEG: YES (prebuilt binaries)
avcodec: YES (ver 57.107.100)
avformat: YES (ver 57.83.100)
avutil: YES (ver 55.78.100)
swscale: YES (ver 4.8.100)
avresample: YES (ver 3.7.0)
GStreamer: NO
DirectShow: YES
Parallel framework: none
Trace: YES (built-in)
Other third-party libraries:
Lapack: NO
Eigen: NO
Custom HAL: NO
Protobuf: build (3.5.1)
NVIDIA CUDA: NO
OpenCL: YES (no extra features)
Include path: E:/opencv_341/opencv/sources/3rdparty/include/opencl/1.2
Link libraries: Dynamic load
Python (for build): E:/Python37-32/python.exe
Java:
ant: NO
JNI: C:/Program Files (x86)/Java/jdk1.8.0_181/include C:/Program Files (x86)/Java/jdk1.8.0_181/include/win32 C:/Program Files (x86)/Java/jdk1.8.0_181/include
Java wrappers: NO
Java tests: NO
Matlab: NO
Install to: E:/opencv_341/opencv_mingw64_build/install
-----------------------------------------------------------------
Configuring done
Generating done
打开终端进行编译：（-j 是使用 8 个线程进行编译，请根据你的计算机配置合理设置线程数）
E:
cd E:\opencv_341\opencv_mingw64_build
mingw32-make -j 8
mingw32-make install
如果 mingw32-make -j 8 遇到错误，请看下面的 编译 OpenCV 常见错误，否则执行 mingw32-make install，完成安装。
[ 49%] Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_dshow.cpp.obj
In file included from E:\opencv_341\opencv\sources\modules\videoio\src\cap_dshow.cpp:113:0:
e:\mingw-w64\x64-4.8.1-release-posix-seh-rev5\mingw64\x86_64-w64-mingw32\include\aviriff.h:2:8: error: expected constructor, destructor, or type conversion before 'file'
* This file is part of the mingw-w64 runtime package.
^
e:\mingw-w64\x64-4.8.1-release-posix-seh-rev5\mingw64\x86_64-w64-mingw32\include\aviriff.h:3:25: error: 'refer' does not name a type
* No warranty is given; refer to the file DISCLAIMER within this package.
^
In file included from e:\mingw-w64\x64-4.8.1-release-posix-seh-rev5\mingw64\x86_64-w64-mingw32\include\aviriff.h:19:0,
from E:\opencv_341\opencv\sources\modules\videoio\src\cap_dshow.cpp:113:
e:\mingw-w64\x64-4.8.1-release-posix-seh-rev5\mingw64\x86_64-w64-mingw32\include\pshpack2.h:7:21: error: expected declaration before end of line
#pragma pack(push,2)
^
modules\videoio\CMakeFiles\opencv_videoio.dir\build.make:146: recipe for target 'modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_dshow.cpp.obj' failed
mingw32-make[2]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_dshow.cpp.obj] Error 1
CMakeFiles\Makefile2:3057: recipe for target 'modules/videoio/CMakeFiles/opencv_videoio.dir/all' failed
mingw32-make[1]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/all] Error 2
Makefile:161: recipe for target 'all' failed
mingw32-make: *** [all] Error 2
打开E:\MinGW-w64\x64-4.8.1-release-posix-seh-rev5\mingw64\x86_64-w64-mingw32\include\aviriff.h
发现第一行的多行注释少了个/符号，加上保存，如下：
/**
* This file is part of the mingw-w64 runtime package.
* No warranty is given; refer to the file DISCLAIMER within this package.
*/
然后重新 Configure-Generate-mingw32-make 就好了。
......
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\videoio\src\cap_msmf.cpp: In member function 'HRESULT {anonymous}::ComPtr<T>::As({anonymous}::ComPtr<U>&) const [with U = IMF2DBuffer; T = IMFMediaBuffer; HRESULT = long int]':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\videoio\src\cap_msmf.cpp:172:5: error: control reaches end of non-void function [-Werror=return-type]
}
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\videoio\src\cap_msmf.cpp: In member function 'T* {anonymous}::ComPtr<T>::operator->() const [with T = IMF2DBuffer]':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\videoio\src\cap_msmf.cpp:149:5: error: control reaches end of non-void function [-Werror=return-type]
}
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\videoio\src\cap_msmf.cpp: In member function 'T* {anonymous}::ComPtr<T>::operator->() const [with T = IMFMediaBuffer]':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\videoio\src\cap_msmf.cpp:149:5: error: control reaches end of non-void function [-Werror=return-type]
}
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\videoio\src\cap_msmf.cpp: In member function 'T* {anonymous}::ComPtr<T>::operator->() const [with T = IMFSinkWriter]':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\videoio\src\cap_msmf.cpp:149:5: error: control reaches end of non-void function [-Werror=return-type]
}
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\videoio\src\cap_msmf.cpp: In member function 'T* {anonymous}::ComPtr<T>::Get() const [with T = IMFMediaBuffer]':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\videoio\src\cap_msmf.cpp:158:5: error: control reaches end of non-void function [-Werror=return-type]
}
^
cc1plus.exe: some warnings being treated as errors
modules\videoio\CMakeFiles\opencv_videoio.dir\build.make:188: recipe for target 'modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_msmf.cpp.obj' failed
mingw32-make[2]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_msmf.cpp.obj] Error 1
CMakeFiles\Makefile2:2556: recipe for target 'modules/videoio/CMakeFiles/opencv_videoio.dir/all' failed
mingw32-make[1]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/all] Error 2
mingw32-make[1]: *** Waiting for unfinished jobs....
[ 58%] Linking CXX shared library ..\..\bin\libopencv_dnn400.dll
[ 59%] Built target opencv_dnn
Makefile:161: recipe for target 'all' failed
mingw32-make: *** [all] Error 2
因为 MinGW 不能编译 OpenCV 的 cap_msmf 那部分代码，具体见我提的 Issue：Failed to compile opencv-4.0.0-alpha using mingw-w64。
所以，在 cmake-gui 编译配置中：
WITH_MSMF然后重新 Configure-Generate-mingw32-make
[ 86%] Building CXX object modules/calib3d/CMakeFiles/opencv_calib3d.dir/src/chessboard.cpp.obj
In file included from E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:7:0:
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.hpp: In constructor 'cv::details::FastX::Parameters::Parameters()':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.hpp:35:36: error: 'M_PI' was not declared in this scope
resolution = float(M_PI*0.25);
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: At global scope:
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:25:42: error: 'M_PI' was not declared in this scope
const float MAX_ANGLE = float(48.0/180.0*M_PI); // max angle between line segments supposed to be straight
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:26:48: error: 'M_PI' was not declared in this scope
const float MIN_COS_ANGLE = float(cos(35.0/180*M_PI)); // min cos angle between board edges
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:29:35: error: 'M_PI' was not declared in this scope
const float RAD2DEG = float(180.0/M_PI);
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: In function 'int cv::details::testPointSymmetry(cv::Mat, cv::Point2f, float, float)':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:217:33: error: 'M_PI' was not declared in this scope
for(double angle=0;angle <= M_PI;angle+=M_PI*0.1)
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: In member function 'void cv::details::FastX::rotate(float, const cv::Mat&, cv::Size, cv::Mat&) const':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:287:110: error: 'M_PI' was not declared in this scope
cv::Mat m = cv::getRotationMatrix2D(cv::Point2f(float(img.cols*0.5),float(img.rows*0.5)),float(angle/M_PI*180),1);
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: In member function 'std::vector<std::vector<float> > cv::details::FastX::calcAngles(const std::vector<cv::Mat>&, std::vector<cv::KeyPoint>&) const':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:393:30: error: 'M_PI' was not declared in this scope
float resolution = float(M_PI/channels);
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: In member function 'void cv::details::FastX::detectImpl(const cv::Mat&, std::vector<cv::Mat>&, std::vector<cv::Mat>&, const cv::Mat&) const':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:631:30: error: 'M_PI' was not declared in this scope
int num = int(0.5001*M_PI/parameters.resolution);
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: In member function 'void cv::details::Ellipse::draw(cv::InputOutputArray, const Scalar&) const':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:721:43: error: 'M_PI' was not declared in this scope
cv::ellipse(img,center,axes,360-angle/M_PI*180,0,360,color);
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: In static member function 'static float cv::details::Chessboard::Board::findMaxPoint(cv::flann::Index&, const cv::Mat&, const cv::details::Ellipse&, float, float, cv::Point2f&)':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:1541:17: error: 'M_PI' was not declared in this scope
if(a1 > M_PI*0.5)
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:1543:16: error: 'M_PI' was not declared in this scope
if(a2> M_PI*0.5)
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: In static member function 'static bool cv::details::Chessboard::Board::estimateSearchArea(const Point2f&, const Point2f&, const Point2f&, float, cv::details::Ellipse&, const Point2f*)':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:1787:28: error: 'M_PI' was not declared in this scope
angle = float(2.0F*M_PI-angle);
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: In member function 'void cv::details::Chessboard::findKeyPoints(const cv::Mat&, std::vector<cv::KeyPoint>&, std::vector<cv::Mat>&, std::vector<std::vector<float> >&, const cv::Mat&) const':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:2793:29: error: 'M_PI' was not declared in this scope
para.resolution = float(M_PI*0.25); // this gives the best results taking interpolation into account
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: In member function 'cv::Mat cv::details::Chessboard::buildData(const std::vector<cv::KeyPoint>&) const':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:2844:30: error: 'M_PI' was not declared in this scope
(*val++) = float(2.0*M_PI-iter->angle/180.0*M_PI);
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp: In member function 'std::vector<cv::KeyPoint> cv::details::Chessboard::getInitialPoints(cv::flann::Index&, const cv::Mat&, const cv::KeyPoint&, float, float, float) const':
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:2874:25: error: 'M_PI' was not declared in this scope
if(angle_temp > M_PI*0.5)
^
E:\opencv-4.0.0-alpha\opencv-4.0.0-alpha\modules\calib3d\src\chessboard.cpp:2879:29: error: 'M_PI' was not declared in this scope
if(angle_temp > M_PI*0.5)
^
modules\calib3d\CMakeFiles\opencv_calib3d.dir\build.make:137: recipe for target 'modules/calib3d/CMakeFiles/opencv_calib3d.dir/src/chessboard.cpp.obj' failed
mingw32-make[2]: *** [modules/calib3d/CMakeFiles/opencv_calib3d.dir/src/chessboard.cpp.obj] Error 1
CMakeFiles\Makefile2:3018: recipe for target 'modules/calib3d/CMakeFiles/opencv_calib3d.dir/all' failed
mingw32-make[1]: *** [modules/calib3d/CMakeFiles/opencv_calib3d.dir/all] Error 2
Makefile:161: recipe for target 'all' failed
mingw32-make: *** [all] Error 2
因为 OpenCV 在 chessboard.cpp、chessboard.hpp、test_chesscorners.cpp 这些代码中有 BUG，使用的应该是 CV_PI 而不是 M_PI 导致的。具体见我提的 Issue：Failed to compile opencv-4.0.0-alpha using mingw-w64
在最新的 master 分支已经解决了这个问题，见我的 PR：M_PI changed to CV_PI
如果你是在 官网 或者 github.com/opencv/opencv/releases 中下的 OpenCV 4.0.0-alpha，可能还会有这个问题，那么你需要把 chessboard.cpp、chessboard.hpp、test_chesscorners.cpp 文件中的 M_PI 全部改为 CV_PI，如我的 commit 所示：M_PI changed to CV_PI (#12645)
然后重新 Configure-Generate-mingw32-make
[ 28%] Building CXX object modules/CMakeFiles/ade.dir/__/3rdparty/ade/ade-0.1.1c/sources/ade/source/alloc.cpp.obj
E:\opencv-4.0.0-rc\opencv-4.0.0-rc-build\3rdparty\ade\ade-0.1.1c\sources\ade\source\alloc.cpp: In function 'void* ade::aligned_alloc(std::size_t, std::size_t)':
E:\opencv-4.0.0-rc\opencv-4.0.0-rc-build\3rdparty\ade\ade-0.1.1c\sources\ade\source\alloc.cpp:31:16: error: 'posix_memalign' was not declared in this scope
auto res = posix_memalign(&ret, std::max(sizeof(void*), alignment), size);
^~~~~~~~~~~~~~
mingw32-make[2]: *** [modules\CMakeFiles\ade.dir\build.make:63: modules/CMakeFiles/ade.dir/__/3rdparty/ade/ade-0.1.1c/sources/ade/source/alloc.cpp.obj] Error 1
mingw32-make[1]: *** [CMakeFiles\Makefile2:884: modules/CMakeFiles/ade.dir/all] Error 2
mingw32-make: *** [Makefile:162: all] Error 2
因为我使用了 MinGW-w64-8.1.0 编译，而新的编译器在 Windows 下不再定义 WIN32，而定义成 _WIN32，如这个 Issue 的问题：error: ‘posix_memalign’ was not declared in this scope #12831
把 opencv-4.0.0-rc-build\3rdparty\ade\ade-0.1.1c\sources\ade\source\alloc.cpp 文件的所有 WIN32 改为 _WIN32，如这个 PR 所做的修改：fix check for win32 #6
然后重新 Configure-Generate-mingw32-make
[ 32%] Building CXX object modules/core/CMakeFiles/opencv_core.dir/src/directx.cpp.obj
E:\opencv-4.1.0\opencv-4.1.0\modules\core\src\directx.cpp: In function 'void cv::directx::__convertToD3D11Texture2DNV(cv::InputAray, ID3D11Texture2D*)':
E:\opencv-4.1.0\opencv-4.1.0\modules\core\src\directx.cpp:1035:5: error: 'D3D11_TEXTURE2D_DESC' was not declared in this scope
D3D11_TEXTURE2D_DESC desc = { 0 };
^~~~~~~~~~~~~~~~~~~~
D3D11_TEXTURE2D_DESC 在 d3d11.h 中定义，貌似在我的机器上找不到定义。反正也不用 D3D11 与 OpenCL 交互，因此可以关闭 WITH_OPENCL_D3D11_NV 这个选项（默认是开的）。可见我的 issue：Error compiling 4.1.0 source code with mingw-w64: ‘D3D11_TEXTURE2D_DESC’ was not declared in this scope #14286
方法一：
在 cmake-gui 编译配置中：
WITH_OPENCL_D3D11_NV然后重新 Configure-Generate-mingw32-make
方法二：
如这个 PR 中对这两个 cmake 文件的修改：cmake: fix WITH_OPENCL_D3D11_NV check #14294，即可先判断是否可以用，再设置默认的 WITH_OPENCL_D3D11_NV
如果以上错误不是你所遇到的，请务必先看下面两个文章中的错误。