Enable cmake options/flag after making the file - c++

Question

I don't have much knowledge about cmake. I installed a package libfreenect2 following the instructions on their github page. The instructions were as follows-
Clone the repository. And follow the cmake step:
cd ..
mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME/freenect2
make
make install
However, after installing I realised the program/package that required libfreenect2 as a dependency required me to use:
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME/freenect2 -DENABLE_CXX11=ON
You may have noticed, it required me to use an extra flag -DENABLE_CXX11=ON. How can I fix this? How can I set ENABLE_CXX11=ON after the whole make process has been completed? By the way what does -D do? (are these -DXXX things called options or flag)
In case your answer is to repeat the whole process again then kindly guide me through the step by step process of deleting the correct files. I don't want to delete other dependencies.
Here are some other stackoverflow answers relating to cmake-
set cmake option(), cmake option to include a directory, What does cmake do
SOLUTION - I used the accepted solution to enable the flag. Even though it worked for my problem (libfreenect2) still it will be amazing if someone could provide an answer which doesn't involve reinstalling.

Answer 1

My warm suggestion would be to repeat the process with that option ON.
First you should delete what was previously generated.
The sequence of commands to follow is the following:
rm -rf build
rm -rf $HOME/freenect2
just to be entirely sure you start from a "clean state".
I don't see the need to do rm -rf $HOME/freenect2 as that files/dir will be overwritten by the new install, but shouldn't hurt.
You can also try the suggestion in the SO post mentioned in one of the comments.
Then repeat the process from the root dir of libfreenect2:
mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME/freenect2 -DENABLE_CXX11=ON
make
make install
Alternatively, if you're entirely sure that you will build libfreenect2 always with that option ENABLE_CXX11=ON, you could explicitely set it ON once and for all in the CMakeLists.txt of libfreenect2, specifically changing the line:
OPTION(ENABLE_CXX11 "Enable C++11 support" OFF)
into
OPTION(ENABLE_CXX11 "Enable C++11 support" ON)
In this last case, you will just need to do
mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=$HOME/freenect2
make
make install
of course after you've cleaned as explained at the beginning.
About -D for CMake, it allows you to pass options. Directly from the documentation:
-D <var>:<type>=<value>
Create a cmake cache entry.
When cmake is first run in an empty build tree, it creates a
CMakeCache.txt file and populates it with customizable settings for
the project. This option may be used to specify a setting that takes
priority over the project’s default value. The option may be repeated
for as many cache entries as desired.
So if there's some project default options that one wants to change/overwrite than it can be done with this.