Draw the recorded instance draws with the variant seed they were recorded with

gl/query.cpp

@@ -2,6 +2,8 @@
 #include "query.h"
 #include "utilities/Globals.h"
 
+#include <cstring>
+
 gl::query::query(targets target)
     : target(target)
 {
@@ -122,3 +124,111 @@ void gl::gpu_timer::collect()
 		m_pending[slot] = false;
 	}
 }
+
+gl::gpu_timeline::~gpu_timeline()
+{
+	for (auto &frame : m_frames)
+	{
+		if (frame.queries[0] != 0)
+			glDeleteQueries(static_cast<GLsizei>(frame.queries.size()), frame.queries.data());
+	}
+}
+
+void gl::gpu_timeline::begin(char const *Name)
+{
+	if (m_active)
+		end();
+
+	collect();
+	auto &frame = m_frames[m_slot];
+	m_active = !frame.pending;
+	if (!m_active)
+		return;
+
+	if (frame.queries[0] == 0)
+		glCreateQueries(GL_TIMESTAMP, static_cast<GLsizei>(frame.queries.size()), frame.queries.data());
+	frame.count = 0;
+	next(Name);
+}
+
+void gl::gpu_timeline::next(char const *Name)
+{
+	if (!m_active)
+		return;
+
+	auto &frame = m_frames[m_slot];
+	// the last mark is kept for end(); past the limit the part under way goes on
+	if (frame.count + 1 >= MARKS)
+		return;
+
+	glQueryCounter(frame.queries[frame.count], GL_TIMESTAMP);
+	frame.names[frame.count] = Name;
+	++frame.count;
+}
+
+void gl::gpu_timeline::end()
+{
+	if (!m_active)
+		return;
+
+	auto &frame = m_frames[m_slot];
+	glQueryCounter(frame.queries[frame.count], GL_TIMESTAMP);
+	frame.names[frame.count] = nullptr;
+	++frame.count;
+	frame.pending = true;
+	m_slot = (m_slot + 1) % SLOTS;
+	m_active = false;
+}
+
+std::vector<gl::gpu_timeline::part> const &gl::gpu_timeline::result()
+{
+	collect();
+	return m_last;
+}
+
+void gl::gpu_timeline::collect()
+{
+	// frames finish in the order they were issued, oldest first
+	for (size_t i = 0; i < SLOTS; ++i)
+	{
+		auto &frame = m_frames[(m_slot + i) % SLOTS];
+		if (!frame.pending)
+			continue;
+
+		auto ready = true;
+		for (size_t mark = 0; (mark < frame.count) && ready; ++mark)
+		{
+			GLint available = GL_FALSE;
+			glGetQueryObjectiv(frame.queries[mark], GL_QUERY_RESULT_AVAILABLE, &available);
+			ready = (available != GL_FALSE);
+		}
+		if (!ready)
+			break;
+
+		m_last.clear();
+		GLuint64 first = 0;
+		GLuint64 previous = 0;
+		for (size_t mark = 0; mark < frame.count; ++mark)
+		{
+			GLuint64 time = 0;
+			glGetQueryObjectui64v(frame.queries[mark], GL_QUERY_RESULT, &time);
+			if (mark == 0)
+				first = time;
+			else
+			{
+				auto const length = (time >= previous ? time - previous : 0);
+				auto const *name = frame.names[mark - 1];
+				auto lookup = m_last.begin();
+				while ((lookup != m_last.end()) && (std::strcmp(lookup->name, name) != 0))
+					++lookup;
+				if (lookup != m_last.end())
+					lookup->time += length;
+				else
+					m_last.push_back({name, length});
+			}
+			previous = time;
+		}
+		m_total = (previous >= first ? previous - first : 0);
+		frame.pending = false;
+	}
+}