From 128926a41b368e166af63515370d9c9367e3dda2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Foucault?= <foucault.clem@gmail.com>
Date: Mon, 11 Jun 2018 11:49:10 +0200
Subject: GHOST: Delay opengl context initialization

This way they can be init in their owner thread. Contexts should not be
shared accross threads. Once you make a context active on a thread it is
owned by the thread.

This commit only have the GLX backend updated but should not break orther
platform.
---
 intern/gawain/src/gwn_vertex_array_id.cpp |  5 +++--
 intern/ghost/intern/GHOST_ContextGLX.cpp  | 30 ++++++++++++++++++++++++------
 intern/ghost/intern/GHOST_ContextGLX.h    |  2 ++
 source/blender/draw/intern/draw_manager.c |  2 ++
 4 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/intern/gawain/src/gwn_vertex_array_id.cpp b/intern/gawain/src/gwn_vertex_array_id.cpp
index ad60dea7542..2ab38a8fe18 100644
--- a/intern/gawain/src/gwn_vertex_array_id.cpp
+++ b/intern/gawain/src/gwn_vertex_array_id.cpp
@@ -18,7 +18,7 @@
 #include <mutex>
 #include <unordered_set>
 
-#if TRUST_NO_ONE
+#if 0
 extern "C" {
 extern int BLI_thread_is_main(void); // Blender-specific function
 }
@@ -68,7 +68,8 @@ static void clear_orphans(Gwn_Context* ctx)
 Gwn_Context* GWN_context_create(void)
 	{
 #if TRUST_NO_ONE
-	assert(thread_is_main());
+	/* We cannot rely on this anymore. */
+	// assert(thread_is_main());
 #endif
 	Gwn_Context* ctx = new Gwn_Context;
 	glGenVertexArrays(1, &ctx->default_vao);
diff --git a/intern/ghost/intern/GHOST_ContextGLX.cpp b/intern/ghost/intern/GHOST_ContextGLX.cpp
index 815189b9098..1365a1a9c24 100644
--- a/intern/ghost/intern/GHOST_ContextGLX.cpp
+++ b/intern/ghost/intern/GHOST_ContextGLX.cpp
@@ -110,6 +110,9 @@ GHOST_TSuccess GHOST_ContextGLX::swapBuffers()
 
 GHOST_TSuccess GHOST_ContextGLX::activateDrawingContext()
 {
+	if (m_init == false) {
+		initContext();
+	}
 	if (m_display) {
 		return ::glXMakeCurrent(m_display, m_window, m_context) ? GHOST_kSuccess : GHOST_kFailure;
 	}
@@ -184,7 +187,8 @@ const bool GLXEW_ARB_create_context_robustness =
 	glxewInit();
 #endif  /* USE_GLXEW_INIT_WORKAROUND */
 
-
+	/* Only init the non-offscreen context directly */
+	const bool do_init = (m_window != None);
 
 	if (GLXEW_ARB_create_context) {
 		int profileBitCore   = m_contextProfileMask & GLX_CONTEXT_CORE_PROFILE_BIT_ARB;
@@ -304,12 +308,27 @@ const bool GLXEW_ARB_create_context_robustness =
 	GHOST_TSuccess success;
 
 	if (m_context != NULL) {
-		const unsigned char *version;
-
 		if (!s_sharedContext)
 			s_sharedContext = m_context;
 
 		s_sharedCount++;
+	}
+
+	if (do_init) {
+		success = initContext();
+	}
+
+	GHOST_X11_ERROR_HANDLERS_RESTORE(handler_store);
+
+	return success;
+}
+
+GHOST_TSuccess GHOST_ContextGLX::initContext()
+{
+	GHOST_TSuccess success;
+
+	if (m_context != NULL) {
+		const unsigned char *version;
 
 		glXMakeCurrent(m_display, m_window, m_context);
 
@@ -341,13 +360,12 @@ const bool GLXEW_ARB_create_context_robustness =
 		success = GHOST_kFailure;
 	}
 
-
-	GHOST_X11_ERROR_HANDLERS_RESTORE(handler_store);
+	/* We tag as init even if it fails. */
+	m_init = true;
 
 	return success;
 }
 
-
 GHOST_TSuccess GHOST_ContextGLX::releaseNativeHandles()
 {
 	m_window = 0;
diff --git a/intern/ghost/intern/GHOST_ContextGLX.h b/intern/ghost/intern/GHOST_ContextGLX.h
index ded1b293659..b4d6a841d72 100644
--- a/intern/ghost/intern/GHOST_ContextGLX.h
+++ b/intern/ghost/intern/GHOST_ContextGLX.h
@@ -116,6 +116,7 @@ public:
 
 private:
 	void initContextGLXEW();
+	GHOST_TSuccess initContext();
 
 	Display *m_display;
 	GLXFBConfig m_fbconfig;
@@ -128,6 +129,7 @@ private:
 	const int m_contextResetNotificationStrategy;
 
 	GLXContext m_context;
+	bool m_init;
 
 	/** The first created OpenGL context (for sharing display lists) */
 	static GLXContext s_sharedContext;
diff --git a/source/blender/draw/intern/draw_manager.c b/source/blender/draw/intern/draw_manager.c
index 65702a65541..5f059f92d5f 100644
--- a/source/blender/draw/intern/draw_manager.c
+++ b/source/blender/draw/intern/draw_manager.c
@@ -2160,6 +2160,8 @@ void DRW_opengl_context_create(void)
 	}
 	/* This changes the active context. */
 	DST.gl_context = WM_opengl_context_create();
+	/* Make the context active for this thread (main thread) */
+	WM_opengl_context_activate(DST.gl_context);
 	/* Be sure to create gawain.context too. */
 	DST.gwn_context = GWN_context_create();
 	if (!G.background) {
-- 
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