diff --git a/openglcanvas.cpp b/openglcanvas.cpp
index 23c0bed5244fd3e95cf4cd0d1095002459daf7ae..ac15b901b7591ce41d4e5e78b8a341d20f3d3be3 100644
--- a/openglcanvas.cpp
+++ b/openglcanvas.cpp
@@ -4,13 +4,14 @@
 #endif
 #include "openglcanvas.h"
 #include <cmath>
-#include <unistd.h>     // for getcwd, getpwuid, getuid
 #include <sys/types.h>  // for fstat, getpwuid, getuid
 #include <sys/stat.h>   // for fstat
-#include <pwd.h>        // for getpwuid (TODO: windows?)
+#ifndef _WIN32
+#  include <pwd.h>        // for getpwuid (TODO: windows?)
+#endif
 #include <cstdio>       // for fopen, fclose, getc
 #include <cstring>
-#ifdef WINDOWS
+#ifdef _WIN32
   #include <direct.h>
   #define GET_WORKDIR _getcwd
 #else
@@ -22,10 +23,14 @@
 #define VERT_SHADER_FILE "test_vertex_shader.vert"
 #define FRAG_SHADER_FILE "fragment_shader.frag"
 
-#define CONST_PI        (0x1.921fb54442d18p+1)
-#define CONST_PI_2      (0x1.921fb54442d18p+0)
-#define CONST_PI_F      (0x1.921fb6p+1)
-#define CONST_PI_2_F    (0x1.921fb6p+0)
+#define CONST_PI        3.141592653589793115997963468544185161590576171875
+#define CONST_PI_2      1.5707963267948965579989817342720925807952880859375
+#define CONST_PI_F      3.1415927410125732421875f
+#define CONST_PI_2_F    1.57079637050628662109375f
+//#define CONST_PI        (0x1.921fb54442d18p+1)
+//#define CONST_PI_2      (0x1.921fb54442d18p+0)
+//#define CONST_PI_F      (0x1.921fb6p+1f)
+//#define CONST_PI_2_F    (0x1.921fb6p+0f)
 
 OpenGLCanvas::OpenGLCanvas(QWidget *parent) :
     QGLWidget(parent)
@@ -188,9 +193,20 @@ void OpenGLCanvas::change_visualization(QString name){
 // options in private variables.
 // TODO: windows
 void OpenGLCanvas::read_config_file(){
+#ifdef _WIN32
+    char *filepath=(char*)malloc(512*sizeof(char));
+    if(!GET_WORKDIR(filepath,512)){
+        fprintf(stderr,"error reading config file\n");
+        exit(-1);
+    }
+    strcat(filepath,"/panorc");
+    // TODO
+#else
     struct passwd *pw=getpwuid(getuid());
     char *filepath=pw->pw_dir;
     strcat(filepath,"/.panorc");
+#endif
+    fprintf(stderr,"the user config file is %s\n",filepath);
     shader_dir=(char*)malloc(512*sizeof(char));
     shader_dir[0]='\0';
     input_image_file=(char*)malloc(512*sizeof(char));
diff --git a/openglcanvas.h b/openglcanvas.h
index eefb5db321f92316dcc9c3447d74e96c4988867e..fa8c3fce4d4e0d445fb82f431d2c667bddb5141d 100644
--- a/openglcanvas.h
+++ b/openglcanvas.h
@@ -19,7 +19,8 @@
   #include <GL/gl.h>
   #include <GL/glu.h>
   #include <GL/glut.h>
-  #include <GL/glext.h>
+  // is glext really needed?
+  //#include <GL/glext.h>
 #endif
 
 #include <QGLWidget>
@@ -27,7 +28,11 @@
 #include <QFile>
 #include <QFileDialog>
 #include <fcntl.h>
-#include <unistd.h>
+#ifdef _WIN32
+  #include <io.h>
+#else
+  #include <unistd.h>   // for getcwd, getpwuid, getuid
+#endif
 #include "chronos.h"
 
 extern "C" {