5 files changed, 36 insertions, 0 deletions
diff --git a/FL/Fl_Gl_Window.H b/FL/Fl_Gl_Window.H
index 65c7a5a9d..67c3c4050 100644
--- a/FL/Fl_Gl_Window.H
+++ b/FL/Fl_Gl_Window.H
@@ -199,6 +199,8 @@ public:
   void context(GLContext, int destroy_flag = 0);
   void make_current();
   void swap_buffers();
+  void swap_interval(int);
+  int swap_interval() const;
   void ortho();
 
   int can_do_overlay();
diff --git a/src/Fl_Gl_Window.cxx b/src/Fl_Gl_Window.cxx
index a3c2641bd..b59d7d5de 100644
--- a/src/Fl_Gl_Window.cxx
+++ b/src/Fl_Gl_Window.cxx
@@ -161,6 +161,21 @@ void Fl_Gl_Window::swap_buffers() {
   pGlWindowDriver->swap_buffers();
 }
 
+/**
+ Sets the rate at which the GL windows swaps buffers.
+ */
+void Fl_Gl_Window::swap_interval(int frames) {
+  pGlWindowDriver->swap_interval(frames);
+}
+
+/**
+ Gets the rate at which the GL windows swaps buffers.
+ */
+int Fl_Gl_Window::swap_interval() const {
+  return pGlWindowDriver->swap_interval();
+}
+
+
 void Fl_Gl_Window::flush() {
   if (!shown()) return;
   uchar save_valid = valid_f_ & 1;
diff --git a/src/Fl_Gl_Window_Driver.H b/src/Fl_Gl_Window_Driver.H
index 839c5bc93..79f696905 100644
--- a/src/Fl_Gl_Window_Driver.H
+++ b/src/Fl_Gl_Window_Driver.H
@@ -69,6 +69,8 @@ public:
   virtual void swap_buffers() {}
   virtual void resize(int /*is_a_resize*/, int /*w*/, int /*h*/) {}
   virtual char swap_type();
+  virtual void swap_interval(int) { }
+  virtual int swap_interval() { return -1; }
   virtual int flush_begin(char&) {return 0;}
   virtual void gl_hide_before(void *&) {} // the default implementation may be enough
   static Fl_Gl_Choice *find_begin(int m, const int *alistp);
diff --git a/src/drivers/Cocoa/Fl_Cocoa_Gl_Window_Driver.H b/src/drivers/Cocoa/Fl_Cocoa_Gl_Window_Driver.H
index 79b93e6df..21a3a4589 100644
--- a/src/drivers/Cocoa/Fl_Cocoa_Gl_Window_Driver.H
+++ b/src/drivers/Cocoa/Fl_Cocoa_Gl_Window_Driver.H
@@ -38,6 +38,8 @@ class Fl_Cocoa_Gl_Window_Driver : public Fl_Gl_Window_Driver {
   void swap_buffers() FL_OVERRIDE;
   void resize(int is_a_resize, int w, int h) FL_OVERRIDE;
   char swap_type() FL_OVERRIDE;
+  void swap_interval(int) FL_OVERRIDE;
+  int swap_interval() FL_OVERRIDE;
   Fl_Gl_Choice *find(int m, const int *alistp) FL_OVERRIDE;
   GLContext create_gl_context(Fl_Window* window, const Fl_Gl_Choice* g) FL_OVERRIDE;
   void set_gl_context(Fl_Window* w, GLContext context) FL_OVERRIDE;
diff --git a/src/drivers/Cocoa/Fl_Cocoa_Gl_Window_Driver.mm b/src/drivers/Cocoa/Fl_Cocoa_Gl_Window_Driver.mm
index a2c8e7578..43bc2d480 100644
--- a/src/drivers/Cocoa/Fl_Cocoa_Gl_Window_Driver.mm
+++ b/src/drivers/Cocoa/Fl_Cocoa_Gl_Window_Driver.mm
@@ -355,6 +355,21 @@ void Fl_Cocoa_Gl_Window_Driver::swap_buffers() {
 
 char Fl_Cocoa_Gl_Window_Driver::swap_type() {return copy;}
 
+void Fl_Cocoa_Gl_Window_Driver::swap_interval(int n) {
+  GLint interval = (GLint)n;
+  NSOpenGLContext* ctx = (NSOpenGLContext*)pWindow->context();
+  if (ctx)
+    [ctx setValues:&interval forParameter:NSOpenGLContextParameterSwapInterval];
+}
+
+int Fl_Cocoa_Gl_Window_Driver::swap_interval() {
+  GLint interval = (GLint)-1;
+  NSOpenGLContext* ctx = (NSOpenGLContext*)pWindow->context();
+  if (ctx)
+    [ctx getValues:&interval forParameter:NSOpenGLContextParameterSwapInterval];
+  return interval;
+}
+
 void Fl_Cocoa_Gl_Window_Driver::resize(int is_a_resize, int w, int h) {
   if (pWindow->shown()) apply_scissor();
   [(NSOpenGLContext*)pWindow->context() update];