Throttle the program to run at max 60fps.

src/glutils.cpp

@@ -4,6 +4,8 @@
 #include <GL/glew.h>
 #include <cstring>
 #include <glog/logging.h>
+#include <chrono>
+#include <thread>
 #include "glutils.hpp"
 
 using namespace fmri;
@@ -86,3 +88,23 @@ void fmri::checkGLErrors()
         }
     }
 }
+
+void fmri::throttleIdleFunc()
+{
+    using namespace std::chrono;
+
+    constexpr duration<double, ratio<1, 60>> refreshRate(1);
+
+    static auto lastCalled = steady_clock::now();
+
+    const auto now = steady_clock::now();
+
+    const auto diff = now - lastCalled;
+
+    if (diff < refreshRate) {
+        const auto remaining = refreshRate - diff;
+        this_thread::sleep_for(remaining);
+    }
+
+    lastCalled = now;
+}

src/glutils.hpp

@@ -38,4 +38,9 @@ namespace fmri {
      * Check if there are OpenGL errors and report them.
      */
     void checkGLErrors();
+
+    /**
+     * Slow down until the idle func is being called a reasonable amount of times.
+     */
+    void throttleIdleFunc();
 }

src/main.cpp

@@ -151,6 +151,7 @@ static void specialKeyFunc(int key, int, int)
 static void idleFunc()
 {
     checkGLErrors();
+    throttleIdleFunc();
 }
 
 int main(int argc, char *argv[])