Pangolin的使用

　　Pangolin 是一个可用于SLAM可视化的openGL库。目前有很多SLAM系统都用它作为可视化的工具。它的编译与安装过程问题不大，依赖也比较少。但最近我在单独使用它的时候，碰到了很奇怪的现象：我单独将HelloPangolin这个example以及它的CMakelists.txt取出来，通过cmake,build的方式去编译，报了一堆错：

In file included from /home/lenovo/Pangolin/include/pangolin/var/var.h:34:0,
from /home/lenovo/Pangolin/include/pangolin/var/varextra.h:31,
from /home/lenovo/Pangolin/include/pangolin/pangolin.h:52,
from /home/lenovo/expangolin/main.cpp:1:
/home/lenovo/Pangolin/include/pangolin/var/varvalue.h: In instantiation of ‘void pangolin::VarValue::Init() [with T = bool]’:
/home/lenovo/Pangolin/include/pangolin/var/varvalue.h:55:14: required from ‘pangolin::VarValue::VarValue(const T&) [with T = bool]’
/home/lenovo/Pangolin/include/pangolin/var/var.h:170:20: required from ‘pangolin::Var::Var(const string&, const T&, bool) [with T = bool; std::string = std::basic_string]’
/home/lenovo/Pangolin/include/pangolin/var/varextra.h:67:52: required from here
/home/lenovo/Pangolin/include/pangolin/var/varvalue.h:99:23: error: ‘class pangolin::VarValue’ has no member named ‘str’
this->str = (VarValueTstd::string*)this;
^
/home/lenovo/Pangolin/include/pangolin/var/varvalue.h:102:23: error: ‘class pangolin::VarValue’ has no member named ‘str’
this->str = str_ptr;

　　出现这种错误，意味着Pangolin库的路径是能够被找到的，但通过这个库编译example的时候，出现了问题。这个问题困扰了很久，最终我通过对比ORB-SLAM2中的CMakeLists.txt才发现，需要通过CMake加上C++11 或者C++0x的support，最终编译pangolin的example的CMakeLists.txt 如下：

cmake_minimum_required(VERSION 2.8)
project(HelloPangolin)

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}  -Wall  -O3 -march=native ")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall   -O3 -march=native")

# Check C++11 or C++0x support
include(CheckCXXCompilerFlag)
CHECK_CXX_COMPILER_FLAG("-std=c++11" COMPILER_SUPPORTS_CXX11)
CHECK_CXX_COMPILER_FLAG("-std=c++0x" COMPILER_SUPPORTS_CXX0X)
if(COMPILER_SUPPORTS_CXX11)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
   add_definitions(-DCOMPILEDWITHC11)
   message(STATUS "Using flag -std=c++11.")
elseif(COMPILER_SUPPORTS_CXX0X)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x")
   add_definitions(-DCOMPILEDWITHC0X)
   message(STATUS "Using flag -std=c++0x.")
else()
   message(FATAL_ERROR "The compiler ${CMAKE_CXX_COMPILER} has no C++11 support. Please use a different C++ compiler.")
endif()

find_package(Pangolin REQUIRED)

include_directories(${Pangolin_INCLUDE_DIRS})

# Build examples
add_executable(test main.cpp)
target_link_libraries(test ${Pangolin_LIBRARIES})