Hi!

On Tue, 23 Nov 2021 04:31:58 -0800 (PST)
Arvind Arya <[email protected]> wrote:

> Thank You sir, 
> I would like to apologise for my lack of understanding. Sir I cannot get 
> references on how to build libraries can you please elaborate a little how 
> to make "*build opencv and its libraries themselves using "em++" / 
> "emcmake *
> *cmake" against the opencv source"*
> 

this script is as far as i got and "emcmake" fails:

```
#! /usr/bin/env bash
#
# shlomif.bash
# Copyright (C) 2021 Shlomi Fish < https://www.shlomifish.org/ >
#
# Distributed under the terms of the MIT license.
#
set -e -x

if ! test -e _opencv
then
    git clone -b 4.5.4 https://github.com/opencv/opencv _opencv
fi

mkdir -p buildopencv
cd buildopencv
emcmake cmake ../_opencv
exit 0

em++ -I _opencv/include/ -I _opencv/modules/core/include/ -I
opencv/4.5.3_2/include/opencv4/ -I opencv/4.5.3_2/include/opencv4/opencv2/
main.cpp -D __OPENCV_BUILD=1 _opencv/modules/core/src/matrix.cpp

```

given I failed to build an emscripten version of opencv too, and you have
required too much hand-holding, I hereby give up on helping you.

Good luck!
> 
> I am really a newbie Sir, this is my first C++ big project. I have the 
> OpenCV  downloaded where do I go from there. I see Modules. I see 
> "OpenCV-Emscripten.cmake " in the folders.
> 
> There are source file are they platform dependent Do I need Makefiles of 
> the src files ?
> 
> Can you explain to me like you would explain to a kid how to go about it?
>  and also you can point me to the literature that will help me in all this 
> because piecing this together from stack overflow and such places is 
> stressing me out. 
> Please Help.
> On Tuesday, November 23, 2021 at 5:20:40 PM UTC+5:30 Shlomi Fish wrote:
> 
> > Hi Arvind!
> >
> > I think I explained it to you already:
> >
> > you need to build opencv and its libraries themselves using "em++" / 
> > "emcmake
> > cmake" against the opencv source (and it doesn't work here for me!).
> >
> > You cannot (!!) reuse the binaries of opencv built using normal gcc/clang 
> > which
> > produce native (= x86-64 /etc.) binaries.
> >
> > On Tue, 23 Nov 2021 01:34:00 -0800 (PST)
> > Arvind Arya <[email protected]> wrote:
> >  
> > > Thank You for the reply, 
> > > Let me tell you how I run it:
> > > I installed openCV in my system and then made this CmakeLists.txt and   
> > then   
> > > ran:
> > > *cmake*.
> > > and then
> > > *make*
> > > and then
> > > .*/startProject*
> > > and it worked natively on my computer.
> > > 
> > > 
> > > You are telling me about Export sets how do I get them in emcmake:
> > > and everything else is fine? I just have so much confusion ? Is the   
> > object   
> > > file made right? Are Libraries made right? Is this Cmake approach bypass 
> > > the need for archiving libraries? Tell me where to go from here.
> > > Thank You Very much.
> > > On Tuesday, November 23, 2021 at 2:31:42 PM UTC+5:30 Shlomi Fish wrote:
> > >   
> > > > Hi Arvind!
> > > >
> > > > On Mon, 22 Nov 2021 02:49:56 -0800 (PST)
> > > > Arvind Arya <[email protected]> wrote:
> > > >   
> > > > > https://github.com/notasuperhero/New
> > > > > Here in the file
> > > > > "What I did here.txt"
> > > > > I explain Everything.
> > > > > Loved your Taylor Swift jokes btw.
> > > > > 
> > > > > Thank You for your help.
> > > > > Arvind.
> > > > > 
> > > > >   
> > > >
> > > > Thanks!
> > > >
> > > > Sorry, but "emcmake cmake ../_opencv/" is failing here:
> > > >
> > > > ```
> > > > that is not in any export set.
> > > >
> > > >
> > > > CMake Error in CMakeLists.txt:
> > > > export called with target "opencv_dnn" which requires target   
> > "libprotobuf"  
> > > > that is not in any export set.
> > > >
> > > >
> > > > CMake Error in CMakeLists.txt:
> > > > export called with target "opencv_imgcodecs" which requires target
> > > > "libjpeg-turbo" that is not in any export set.
> > > >
> > > >
> > > > CMake Error in CMakeLists.txt:
> > > > export called with target "opencv_imgcodecs" which requires target
> > > > "libwebp" that is not in any export set.
> > > >
> > > >
> > > > CMake Error in CMakeLists.txt:
> > > > export called with target "opencv_imgcodecs" which requires target   
> > "libpng"  
> > > > that is not in any export set.
> > > >
> > > >
> > > > CMake Error in CMakeLists.txt:
> > > > export called with target "opencv_imgcodecs" which requires target
> > > > "libtiff" that is not in any export set.
> > > >
> > > >
> > > > CMake Error in CMakeLists.txt:
> > > > export called with target "opencv_imgcodecs" which requires target
> > > > "libopenjp2" that is not in any export set.
> > > >
> > > >
> > > > CMake Error in CMakeLists.txt:
> > > > export called with target "opencv_imgcodecs" which requires target   
> > "zlib"  
> > > > that is not in any export set.
> > > >
> > > >
> > > > CMake Error in CMakeLists.txt:
> > > > export called with target "opencv_objdetect" which requires target   
> > "quirc"  
> > > > that is not in any export set.
> > > >
> > > >
> > > > CMake Error in CMakeLists.txt:
> > > > export called with target "opencv_gapi" which requires target "ade"   
> > that is  
> > > > not in any export set.
> > > >
> > > >
> > > > CMake Error in CMakeLists.txt:
> > > > export called with target "opencv_gapi" which requires target   
> > "ittnotify"  
> > > > that is not in any export set.
> > > >
> > > >
> > > > -- Generating done
> > > > CMake Generate step failed. Build files cannot be regenerated   
> > correctly.  
> > > > emcmake: error: 'cmake
> > > >
> > > >   
> > -DCMAKE_CROSSCOMPILING_EMULATOR=/home/shlomif/Download/unpack/prog/llvm-to-js/emsdk/node/14.15.5_64bit/bin/node
> >  
> > > >
> > > >   
> > -DCMAKE_TOOLCHAIN_FILE=/home/shlomif/Download/unpack/prog/llvm-to-js/emsdk/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake
> >  
> > > > ../_opencv' failed (returned 1) [shlomif@telaviv1 scmake]$
> > > >
> > > > ```
> > > >
> > > >   
> > > > > On Monday, November 22, 2021 at 12:18:19 PM UTC+5:30 Shlomi Fish   
> > wrote:  
> > > > >   
> > > > > > Hi Arvind!
> > > > > >
> > > > > > I see your replies here:
> > > > > > https://groups.google.com/g/emscripten-discuss/c/rgIlaL5prEE
> > > > > >
> > > > > > Otherwise:
> > > > > >
> > > > > > 1. using claws-mail, your email formatting is bad. Perhaps use an 
> > > > > > .asciidoc or
> > > > > > .md file on github/etc.
> > > > > >
> > > > > > 2. i don't know how the lib*.a files were generated.
> > > > > >
> > > > > > 3. Please give an SSCCE - read the whole of
> > > > > > https://github.com/shlomif/how-to-share-code-online and
> > > > > > https://github.com/shlomif/writing-the-perfect-question (no   
> > > > excuses!).   
> > > > > > Perhaps
> > > > > > use github actions.
> > > > > >
> > > > > > On Sun, 21 Nov
> > > > > > 2021 23:54:35 +0530 Arvind Arya <[email protected]> wrote:
> > > > > >   
> > > > > > > First I remember an Ad when Expedia try to make in India
> > > > > > > https://www.youtube.com/watch?v=Rmadver1Xdk.
> > > > > > > Rajnikant once won the world series of poker using UNO cards.
> > > > > > > 
> > > > > > > Sorry I had to leave town due to some unforeseen circumstances.   
> > > > Thank you   
> > > > > > > for asking I am still stuck. I was able to link the header files
> > > > > > >  
> > I   
> > > > made   
> > > > > > the   
> > > > > > > object file main.o and the I am having trouble linking the   
> > library   
> > > > > > archives   
> > > > > > > I tried everything
> > > > > > > 
> > > > > > > 
> > > > > > > *ld main.o libopencv_core.a libopencv_imgcodecs.a*
> > > > > > > 
> > > > > > > *ld: symbol(s) not found for architecture x86_64*
> > > > > > > *clang: error: linker command failed with exit code 1 (use -v to
> > > > > > >  
> > see  
> > > > > > > invocation)*
> > > > > > > 
> > > > > > > 
> > > > > > > tried the same command with* gcc and g++ The same error/*
> > > > > > > I combined the archives with command: *ar rcs   
> > all_the_object_files.o  
> > > > > > >   
> > > > to   
> > > > > > > newib.a*
> > > > > > > *tried with *
> > > > > > > 
> > > > > > > *emcc main.cpp newlib.a -o hello.html --emrun*
> > > > > > > 
> > > > > > > emcc: warning: newlib.a: archive is missing an index; Use emar   
> > when  
> > > > > > > creating libraries to ensure an index is created [-Wemcc]
> > > > > > > emcc: warning: newlib.a: adding index [-Wemcc]
> > > > > > > error: undefined symbol: _ZN2cv3MatD1Ev (referenced by top-level
> > > > > > >  
> > > > compiled   
> > > > > > > C/C++ code)
> > > > > > > warning: Link with `-s LLD_REPORT_UNDEFINED` to get more   
> > information  
> > > > > > >   
> > > > on   
> > > > > > > undefined symbols
> > > > > > > warning: To disable errors for undefined symbols use `-s
> > > > > > > ERROR_ON_UNDEFINED_SYMBOLS=0`
> > > > > > > 
> > > > > > > 
> > > > > > > A lot of Errors. How do I link these libraries with the object   
> > file.  
> > > > > > > Thank You So much. I was wondering would it be so rude to ask   
> > you   
> > > > now.   
> > > > > > *Thank   
> > > > > > > you very much.*
> > > > > > > *Arvind from Emscripten Group(My replies keep getting deleted   
> > > > there)*   
> > > > > >
> > > > > >
> > > > > >
> > > > > > -- 
> > > > > >
> > > > > > Shlomi Fish https://www.shlomifish.org/
> > > > > > https://www.shlomifish.org/humour/bits/facts/Emma-Watson/
> > > > > >
> > > > > > Fortran - there isn’t a way to do it... oh wait! Now there is.
> > > > > > — https://www.shlomifish.org/humour/ways_to_do_it.html
> > > > > >
> > > > > > Please reply to list if it's a mailing list post -   
> > > > https://shlom.in/reply   
> > > > > > .
> > > > > >   
> > > > >   
> > > >
> > > >
> > > >
> > > > -- 
> > > >
> > > > Shlomi Fish https://www.shlomifish.org/
> > > > “So, who the hell is Qoheleth?” - https://shlom.in/qoheleth
> > > >
> > > > Chuck Norris round house kicks doors open instead of using their keys.
> > > > Summer Glau makes sure doors are open using her mind.
> > > > — https://www.shlomifish.org/humour/bits/facts/Summer-Glau/
> > > >
> > > > Please reply to list if it's a mailing list post -   
> > https://shlom.in/reply   
> > > > .
> > > >   
> > >   
> >
> >
> >
> > -- 
> >
> > Shlomi Fish https://www.shlomifish.org/
> > https://www.shlomifish.org/humour/bits/facts/Taylor-Swift/
> >
> > Lone Starr: “Just what we need — a Druish princess.”
> > Barf: “Funny! She doesn’t look Druish.”
> > — Spaceballs, https://www.imdb.com/title/tt0094012/
> >
> > Please reply to list if it's a mailing list post - https://shlom.in/reply 
> > .
> >  
> 



-- 

Shlomi Fish       https://www.shlomifish.org/
Humanity - Parody of Modern Life - https://shlom.in/humanity

Wikipedia has a page about everything including the
https://en.wikipedia.org/wiki/Kitchen_sink .

    — https://www.shlomifish.org/humour.html

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