milek7/sim branch opengl 3.3 renderer import

gl/fence.cpp

@@ -0,0 +1,20 @@
+#include "stdafx.h"
+#include "fence.h"
+
+gl::fence::fence()
+{
+    sync = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
+}
+
+gl::fence::~fence()
+{
+    glDeleteSync(sync);
+}
+
+bool gl::fence::is_signalled()
+{
+    GLsizei len = 0;
+    GLint val;
+    glGetSynciv(sync, GL_SYNC_STATUS, 1, &len, &val);
+    return len == 1 && val == GL_SIGNALED;
+}