Raspberry Pi: Pi 2 with Pi Mapper ---- 2/3

since: 2015/08/13
update: 2016/06/08
reference:
1. PiMapper
2. Raspberry Pi: Pi 2 with Pi Mapper ---- 1/3
3. Raspberry Pi 2 Setup Guide

B. 安裝 openFrameworks
     1. 確認目前所安裝的 Raspbian "wheezy" 是 "hard float", 而非 "soft-float" 版本.
          -> "hard float" 版本才會有 /lib/arm-linux-gnueabihf 這目錄;
      "soft-float" 版本才會有 /lib/arm-linux-gnueabi 目錄.

         p.s. Hard float just means the floating point calculations are done by
                on chip hardware rather than being emulated by software.

     2. 設定 Pi:
         a. 說明:
              Raspberry Pi 2 uses the armv7 architecture,
              here will install openFrameworks (0.8.4)

         b. Expand the file system:
             $ sudo raspi-config
             選擇: 1. Expand Filesystem -> Select > Ok

         c. 編譯 openFrameworks 前, 須先確認 CPU 有 192MB 的RAM可使用.
            (先將分配給 GPU 的記憶體縮小, 之後再改回來)
           選擇: 8. Advanced Options > Select

           選擇: A3. Memory split: Change the amount of memory made available
                                                 to the GPU > Select

            輸入: 64 > OK > YES > reboot
      (限制分配給 GPU 的記憶體; 提供較多的記憶體給 CPU 使用)

     結果:
     $ df -h

     3. 更新套件:
         $ sudo apt-get clean
         $ sudo apt-get update
    // 或: $ sudo apt-get update --fix-missing
         $ sudo apt-get upgrade

     4. 下載 openFrameworks 0.8.4 linuxarmv7 distribution
          $ cd ~
          $ curl -O http://www.openframeworks.cc/versions/v0.8.4/of_v0.8.4_linuxarmv7l_release.tar.gz



    5. 解壓縮檔案:
         $ cd ~
         $ tar xvf of_v0.8.4_linuxarmv7l_release.tar.gz

     6. Add the updated Raspberry Pi 2 makefiles to the release
        $ cd ~
        $ curl https://raw.githubusercontent.com/openframeworks/openFrameworks/master/libs/openFrameworksCompiled/project/linuxarmv7l/config.linuxarmv7l.rpi2.mk -o of_v0.8.4_linuxarmv7l_release/libs/openFrameworksCompiled/project/linuxarmv7l/config.linuxarmv7l.rpi2.mk

     7. Install the linux dependencies:
      $ cd ~/of_v0.8.4_linuxarmv7l_release/scripts/linux/debian/
      $ sudo ./install_dependencies.sh    (約 7 分鐘)
     
     8. Set an environmental variable:
         This must be done before using the makefile system each time you enter a new
         terminal or restart the Raspberry Pi 2. It can be automated by adding it to the
         end of your bash init script (e.g. your bash ~/.profile file).

         The following tells the make system to use all 4 cores for compiling and to use
         the Raspberry Pi 2 variant of the armv7 makefiles.
         $ sudo nano ~/.profile
     
         # ctrl + g : get help
         # ctrl + o : write
         # ctrl + x : exit
         ....
        # openframeworks: to use all 4 cores for compiling & armv7 makefiles    
        export MAKEFLAGS=-j4 PLATFORM_VARIANT=rpi2
     
        # check the changes
        $ cat ~/.profile
  
     9. logout & login again

    10. 由於已經編譯好 openFrameworks 了, 我們可以將之前限制分配給 GPU 的
          64 MB 記憶體, 調整為 256 MB(或者更多). 

    11. Compile an example:
          $ cd ~/of_v0.8.4_linuxarmv7l_release/examples/3d/3DPrimitivesExample/   
          $ make
          $ make run (須在 Pi 2 上才看得到結果)