/in/ex3.cpp:5:23: error: implicit conversion loses floating-point precision: 'double' to 'const float' [-Werror,-Wconversion]
static const float PI=3.1415926535;
                   ~~ ^~~~~~~~~~~~
/in/ex3.cpp:111:21: error: implicit conversion loses floating-point precision: 'double' to 'GLfloat' (aka 'float') [-Werror,-Wconversion]
        glVertex2f(cp.x+r*cos(angle),cp.y+r*sin(angle));
        ~~~~~~~~~~ ~~~~^~~~~~~~~~~~~
/in/ex3.cpp:111:39: error: implicit conversion loses floating-point precision: 'double' to 'GLfloat' (aka 'float') [-Werror,-Wconversion]
        glVertex2f(cp.x+r*cos(angle),cp.y+r*sin(angle));
        ~~~~~~~~~~                   ~~~~^~~~~~~~~~~~~
/in/ex3.cpp:147:19: error: implicit conversion changes signedness: 'int' to 'unsigned int' [-Werror,-Wsign-conversion]
    glutTimerFunc(n, TimeStep, n); 
    ~~~~~~~~~~~~~ ^
4 errors generated.