From b5194bbb04237bafae1bf437f38fcb06be70c0e1 Mon Sep 17 00:00:00 2001
From: Elias Naur <elias.naur@gmail.com>
Date: Sat, 3 Jan 2004 08:09:17 +0000
Subject: [PATCH] Implemented linux swap control through GLX_SGI_swap_control

---
 src/native/common/extgl.cpp                  | 13 ++++++++++
 src/native/common/extgl.h                    |  6 +++++
 src/native/linux/org_lwjgl_opengl_Window.cpp | 25 +++++++++-----------
 3 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/src/native/common/extgl.cpp b/src/native/common/extgl.cpp
index 980c0899..0ba1ce7c 100755
--- a/src/native/common/extgl.cpp
+++ b/src/native/common/extgl.cpp
@@ -87,6 +87,9 @@ glXWaitXPROC glXWaitX = NULL;
 glXGetClientStringPROC glXGetClientString = NULL;
 glXQueryServerStringPROC glXQueryServerString = NULL;
 glXQueryExtensionsStringPROC glXQueryExtensionsString = NULL;
+
+/* GLX_SGI_swap_control */
+glXSwapIntervalSGIPROC glXSwapIntervalSGI = NULL;
 #endif
 
 #ifdef _AGL
@@ -2538,6 +2541,15 @@ static void extgl_InitGLXSupportedExtensions(JNIEnv *env, jobject ext_set, Displ
 {
 	extgl_Extensions.GLX_EXT_visual_info = GLXQueryExtension(env, ext_set, disp, screen, "GLX_EXT_visual_info");
 	extgl_Extensions.GLX_EXT_visual_rating = GLXQueryExtension(env, ext_set, disp, screen, "GLX_EXT_visual_rating");
+	extgl_Extensions.GLX_SGI_swap_control = GLXQueryExtension(env, ext_set, disp, screen, "GLX_SGI_swap_control");
+}
+
+static void extgl_InitGLXSGISwapControl(JNIEnv *env, jobject ext_set)
+{
+	if (extgl_Extensions.GLX_SGI_swap_control != 1)
+		return;
+	glXSwapIntervalSGI = (glXSwapIntervalSGIPROC)extgl_GetProcAddress("glXSwapIntervalSGI");
+	EXTGL_SANITY_CHECK(env, ext_set, GLX_SGI_swap_control)
 }
 
 bool extgl_InitGLX(JNIEnv *env, jobject ext_set, Display *disp, int screen)
@@ -2556,6 +2568,7 @@ bool extgl_InitGLX(JNIEnv *env, jobject ext_set, Display *disp, int screen)
 	if (major > 1 || (major == 1 && minor >= 3))
 		extgl_Extensions.GLX13 = true;
 	extgl_InitGLX13(env, ext_set);
+	extgl_InitGLXSGISwapControl(env, ext_set);
 	return true;
 }
 #endif
diff --git a/src/native/common/extgl.h b/src/native/common/extgl.h
index 9e93f1a0..6603a6b3 100644
--- a/src/native/common/extgl.h
+++ b/src/native/common/extgl.h
@@ -539,6 +539,11 @@ extern glXGetClientStringPROC glXGetClientString;
 extern glXQueryServerStringPROC glXQueryServerString;
 extern glXQueryExtensionsStringPROC glXQueryExtensionsString;
 
+/* GLX_SGI_swap_control */
+typedef void (APIENTRY * glXSwapIntervalSGIPROC)(int interval);
+
+extern glXSwapIntervalSGIPROC glXSwapIntervalSGI;
+
 #endif /* X11 */
 
 #ifdef _AGL
@@ -5535,6 +5540,7 @@ struct ExtensionTypes
     bool GLX13;
     bool GLX_EXT_visual_info;
     bool GLX_EXT_visual_rating;
+    bool GLX_SGI_swap_control;
 #endif /* X11 */
     
     bool OpenGL12;
diff --git a/src/native/linux/org_lwjgl_opengl_Window.cpp b/src/native/linux/org_lwjgl_opengl_Window.cpp
index 12dc1c93..c8f71397 100644
--- a/src/native/linux/org_lwjgl_opengl_Window.cpp
+++ b/src/native/linux/org_lwjgl_opengl_Window.cpp
@@ -68,6 +68,7 @@ static int current_width;
 static bool input_released;
 
 static bool dirty;
+static bool vsync_enabled;
 static bool minimized;
 static bool focused;
 static bool closerequested;
@@ -182,7 +183,7 @@ static void createWindow(JNIEnv* env, Display *disp, int screen, XVisualInfo *vi
 	focused = true;
 	minimized = false;
 	closerequested = false;
-
+	vsync_enabled = false;
 	Window root_win;
 	Window win;
 	XSetWindowAttributes attribs;
@@ -556,25 +557,21 @@ JNIEXPORT jboolean JNICALL Java_org_lwjgl_opengl_Window_nIsFocused
 	return focused;
 }
 
-/*
- * Class:     org_lwjgl_opengl_Window
- * Method:    nIsVSyncEnabled
- * Signature: ()Z
- */
 JNIEXPORT jboolean JNICALL Java_org_lwjgl_opengl_Window_nIsVSyncEnabled
   (JNIEnv * env, jclass clazz)
 {
-	// Always return false
-	return false;
+	return vsync_enabled;
 }
 
-/*
- * Class:     org_lwjgl_opengl_Window
- * Method:    nSetVSyncEnabled
- * Signature: (Z)V
- */
 JNIEXPORT void JNICALL Java_org_lwjgl_opengl_Window_nSetVSyncEnabled
   (JNIEnv * env, jclass clazz, jboolean sync)
 {
-	// Do nothing on Linux
+	if (extgl_Extensions.GLX_SGI_swap_control) {
+		bool vsync = sync == JNI_TRUE ? true : false;
+		if (vsync != vsync_enabled) {
+			int interval = vsync ? 1 : 0;
+			glXSwapIntervalSGI(interval);
+			vsync_enabled = vsync;
+		}
+	}
 }