non linear slider for brush tip control

engine/util.cpp

@@ -49,6 +49,19 @@ static const char* gl2str(GLenum err)
     }
 }
 
+double now_seconds()
+{
+    time_t timer;
+    struct tm y2k = { 0 };
+    double seconds;
+
+    y2k.tm_hour = 0;   y2k.tm_min = 0; y2k.tm_sec = 0;
+    y2k.tm_year = 100; y2k.tm_mon = 0; y2k.tm_mday = 1;
+
+    time(&timer);  /* get current time; same as: timer = time(NULL)  */
+    seconds = difftime(timer, mktime(&y2k));
+}
+
 void check_OpenGLError(const char* stmt, const char* fname, int line)
 {
     GLenum err;