+class GPUTimers {
+public:
+ void print();
+ pair<GLuint, GLuint> begin_timer(const string &name, int level);
+
+private:
+ struct Timer {
+ string name;
+ int level;
+ pair<GLuint, GLuint> query;
+ };
+ vector<Timer> timers;
+};
+
+pair<GLuint, GLuint> GPUTimers::begin_timer(const string &name, int level)
+{
+ GLuint queries[2];
+ glGenQueries(2, queries);
+ glQueryCounter(queries[0], GL_TIMESTAMP);
+
+ Timer timer;
+ timer.name = name;
+ timer.level = level;
+ timer.query.first = queries[0];
+ timer.query.second = queries[1];
+ timers.push_back(timer);
+ return timer.query;
+}
+
+void GPUTimers::print()
+{
+ for (const Timer &timer : timers) {
+ // NOTE: This makes the CPU wait for the GPU.
+ GLuint64 time_start, time_end;
+ glGetQueryObjectui64v(timer.query.first, GL_QUERY_RESULT, &time_start);
+ glGetQueryObjectui64v(timer.query.second, GL_QUERY_RESULT, &time_end);
+ //fprintf(stderr, "GPU time used = %.1f ms\n", time_elapsed / 1e6);
+ for (int i = 0; i < timer.level * 2; ++i) {
+ fprintf(stderr, " ");
+ }
+ fprintf(stderr, "%-30s %4.1f ms\n", timer.name.c_str(), (time_end - time_start) / 1e6);
+ }
+}
+
+// A simple RAII class for timing until the end of the scope.
+class ScopedTimer {
+public:
+ ScopedTimer(const string &name, GPUTimers *timers)
+ : timers(timers), level(0)
+ {
+ query = timers->begin_timer(name, level);
+ }
+
+ ScopedTimer(const string &name, ScopedTimer *parent_timer)
+ : timers(parent_timer->timers),
+ level(parent_timer->level + 1)
+ {
+ query = timers->begin_timer(name, level);
+ }
+
+ ~ScopedTimer()
+ {
+ end();
+ }
+
+ void end()
+ {
+ if (!ended) {
+ glQueryCounter(query.second, GL_TIMESTAMP);
+ ended = true;
+ }
+ }
+
+private:
+ GPUTimers *timers;
+ int level;
+ pair<GLuint, GLuint> query;
+ bool ended = false;
+};
+