From 3ed584d1c7e61ad9ff86a4a804b5cc85e7d0cf32 Mon Sep 17 00:00:00 2001
From: Thomas Breloff <tom@breloff.com>
Date: Thu, 23 Jun 2016 16:42:05 -0400
Subject: [PATCH 1/2] added 30 fps throttle to renderloop

---
 src/render.jl | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/render.jl b/src/render.jl
index 5be80a4..9ff207d 100644
--- a/src/render.jl
+++ b/src/render.jl
@@ -37,13 +37,26 @@ function pollwindow(window)
        sleep(1/60)
     end
 end
+
+# nanoseconds between each frame
+const _ns_per_frame = 1e9 / 30
+
 """
 Blocking renderloop
 """
 function renderloop(window::Screen)
+    nw = time_ns()
     while isopen(window)
         render_frame(window)
         GLFW.PollEvents()
+
+        # if we've gone too fast, sleep for the remaining time
+        ns_diff = time_ns() - nw
+        nw += ns_diff
+        if ns_diff < _ns_per_frame
+            secs = (_ns_per_frame - ns_diff) * 1e-9
+            sleep(secs)
+        end
     end
     empty!(window)
     yield()

From 6dff324a11d28da945a38ec4d601b617a310f360 Mon Sep 17 00:00:00 2001
From: Thomas Breloff <tom@breloff.com>
Date: Sun, 26 Jun 2016 09:24:50 -0400
Subject: [PATCH 2/2] GLVISUALIZE_FPS env var, defaults to 60 fps throttle

---
 src/render.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/render.jl b/src/render.jl
index 9ff207d..64ee10a 100644
--- a/src/render.jl
+++ b/src/render.jl
@@ -39,7 +39,7 @@ function pollwindow(window)
 end
 
 # nanoseconds between each frame
-const _ns_per_frame = 1e9 / 30
+const _ns_per_frame = round(UInt64, 1e9 / parse(Float64, get(ENV, "GLVISUALIZE_FPS", "60")))
 
 """
 Blocking renderloop