Ghost: Fix offline OGL render on windows.

rBe0c088f8fb5a introduced offline rendering support on windows, sadly it was trying to use the desktop window for getting a context, which given SetPixelFormat can only be called once for any given HDC was an unfortunate choice.

This patch uses a temporary hidden window for getting the opengl context.

Reviewers: mano-wii

Differential Revision: https://developer.blender.org/D3481

3 files changed, 17 insertions, 90 deletions

diff --git a/intern/ghost/intern/GHOST_ContextWGL.cpp b/intern/ghost/intern/GHOST_ContextWGL.cpp
index 0331958c34a..0047a88fa1d 100644
--- a/intern/ghost/intern/GHOST_ContextWGL.cpp
+++ b/intern/ghost/intern/GHOST_ContextWGL.cpp
@@ -62,7 +62,6 @@ GHOST_ContextWGL::GHOST_ContextWGL(
         int contextFlags,
         int contextResetNotificationStrategy)
     : GHOST_Context(stereoVisual, numOfAASamples),
-      m_dummyPbuffer(NULL),
       m_hWnd(hWnd),
       m_hDC(hDC),
       m_contextProfileMask(contextProfileMask),
@@ -80,6 +79,7 @@ GHOST_ContextWGL::GHOST_ContextWGL(
       m_dummyVersion(NULL)
 #endif
 {
+	assert(m_hDC != NULL);
 }
 
 
@@ -99,12 +99,6 @@ GHOST_ContextWGL::~GHOST_ContextWGL()
 
 			WIN32_CHK(::wglDeleteContext(m_hGLRC));
 		}
-		if (m_dummyPbuffer) {
-			if (m_hDC != NULL)
-				WIN32_CHK(::wglReleasePbufferDCARB(m_dummyPbuffer, m_hDC));
-
-			WIN32_CHK(::wglDestroyPbufferARB(m_dummyPbuffer));
-		}
 	}
 
 #ifndef NDEBUG
@@ -328,38 +322,10 @@ static HWND clone_window(HWND hWnd, LPVOID lpParam)
 	return hwndCloned;
 }
 
-/* It can happen that glew has not been init yet but we need some wgl functions.
- * This create a dummy context on the screen window and init glew to have correct
- * functions pointers. */
-static GHOST_TSuccess forceInitWGLEW(int iPixelFormat, PIXELFORMATDESCRIPTOR &chosenPFD)
-{
-	HDC   dummyHDC = GetDC(NULL);
-
-	if (!WIN32_CHK(::SetPixelFormat(dummyHDC, iPixelFormat, &chosenPFD)))
-		return GHOST_kFailure;
-
-	HGLRC dummyHGLRC = ::wglCreateContext(dummyHDC);
-
-	if (!WIN32_CHK(dummyHGLRC != NULL))
-		return GHOST_kFailure;
-
-	if (!WIN32_CHK(::wglMakeCurrent(dummyHDC, dummyHGLRC)))
-		return GHOST_kFailure;
-
-	if (GLEW_CHK(glewInit()) != GLEW_OK)
-		return GHOST_kFailure;
-
-	WIN32_CHK(::wglDeleteContext(dummyHGLRC));
-
-	WIN32_CHK(ReleaseDC(NULL, dummyHDC));
-
-	return GHOST_kSuccess;
-}
 
 void GHOST_ContextWGL::initContextWGLEW(PIXELFORMATDESCRIPTOR &preferredPFD)
 {
 	HWND  dummyHWND  = NULL;
-	HPBUFFERARB dummyhBuffer = NULL;
 
 	HDC   dummyHDC   = NULL;
 	HGLRC dummyHGLRC = NULL;
@@ -394,19 +360,6 @@ void GHOST_ContextWGL::initContextWGLEW(PIXELFORMATDESCRIPTOR &preferredPFD)
 
 		dummyHDC = GetDC(dummyHWND);
 	}
-	else {
-		int iAttribList[] = {0};
-
-		if (wglCreatePbufferARB == NULL) {
-			/* This should only happen in background mode when rendering with opengl engine. */
-			if (forceInitWGLEW(iPixelFormat, chosenPFD) != GHOST_kSuccess) {
-				goto finalize;
-			}
-		}
-
-		dummyhBuffer = wglCreatePbufferARB(m_hDC, iPixelFormat, 1, 1, iAttribList);
-		dummyHDC = wglGetPbufferDCARB(dummyhBuffer);
-	}
 
 	if (!WIN32_CHK(dummyHDC != NULL))
 		goto finalize;
@@ -449,12 +402,6 @@ finalize:
 
 		WIN32_CHK(::DestroyWindow(dummyHWND));
 	}
-	else if (dummyhBuffer != NULL) {
-		if (dummyHDC != NULL)
-			WIN32_CHK(::wglReleasePbufferDCARB(dummyhBuffer, dummyHDC));
-
-		WIN32_CHK(::wglDestroyPbufferARB(dummyhBuffer));
-	}
 }
 
 
@@ -816,9 +763,7 @@ GHOST_TSuccess GHOST_ContextWGL::initializeDrawingContext()
 	HDC prevHDC = ::wglGetCurrentDC();
 	WIN32_CHK(GetLastError() == NO_ERROR);
 
-	const bool create_hDC = m_hDC == NULL;
-
-	if (!WGLEW_ARB_create_context || create_hDC || ::GetPixelFormat(m_hDC) == 0) {
+	if (!WGLEW_ARB_create_context || ::GetPixelFormat(m_hDC) == 0) {
 		const bool needAlpha = m_alphaBackground;
 
 #ifdef GHOST_OPENGL_STENCIL
@@ -835,14 +780,6 @@ GHOST_TSuccess GHOST_ContextWGL::initializeDrawingContext()
 		int iPixelFormat;
 		int lastPFD;
 
-		if (create_hDC) {
-			/* get a handle to a device context with graphics accelerator enabled */
-			m_hDC = wglGetCurrentDC();
-			if (m_hDC == NULL) {
-				m_hDC = GetDC(NULL);
-			}
-		}
-
 		PIXELFORMATDESCRIPTOR chosenPFD;
 
 		iPixelFormat = choose_pixel_format(m_stereoVisual, m_numOfAASamples, needAlpha, needStencil, sRGB);
@@ -851,13 +788,6 @@ GHOST_TSuccess GHOST_ContextWGL::initializeDrawingContext()
 			goto error;
 		}
 
-		if (create_hDC) {
-			/* create an off-screen pixel buffer (Pbuffer) */
-			int iAttribList[] = {0};
-			m_dummyPbuffer = wglCreatePbufferARB(m_hDC, iPixelFormat, 1, 1, iAttribList);
-			m_hDC = wglGetPbufferDCARB(m_dummyPbuffer);
-		}
-
 		lastPFD = ::DescribePixelFormat(m_hDC, iPixelFormat, sizeof(PIXELFORMATDESCRIPTOR), &chosenPFD);
 
 		if (!WIN32_CHK(lastPFD != 0)) {
@@ -963,22 +893,13 @@ GHOST_TSuccess GHOST_ContextWGL::initializeDrawingContext()
 		goto error;
 	}
 
-	/* Only init the non-offscreen context directly */
-	if (!create_hDC) {
-		initContext();
+	initContext();
 
-		initClearGL();
-		::SwapBuffers(m_hDC);
-	}
+	initClearGL();
+	::SwapBuffers(m_hDC);
 
 	return GHOST_kSuccess;
 error:
-	if (m_dummyPbuffer) {
-		if (m_hDC != NULL)
-			WIN32_CHK(::wglReleasePbufferDCARB(m_dummyPbuffer, m_hDC));
-
-		WIN32_CHK(::wglDestroyPbufferARB(m_dummyPbuffer));
-	}
 	::wglMakeCurrent(prevHDC, prevHGLRC);
 	return GHOST_kFailure;
 
diff --git a/intern/ghost/intern/GHOST_ContextWGL.h b/intern/ghost/intern/GHOST_ContextWGL.h
index b77a50ae23e..7711f90a9e9 100644
--- a/intern/ghost/intern/GHOST_ContextWGL.h
+++ b/intern/ghost/intern/GHOST_ContextWGL.h
@@ -144,10 +144,6 @@ private:
 
 	void initContextWGLEW(PIXELFORMATDESCRIPTOR &preferredPFD);
 
-	/* offscreen buffer with size of 1x1 pixel,
-	 * kept here to release the device constext when closing the program. */
-	HPBUFFERARB m_dummyPbuffer;
-
 	HWND m_hWnd;
 	HDC  m_hDC;
 	bool m_init;
diff --git a/intern/ghost/intern/GHOST_SystemWin32.cpp b/intern/ghost/intern/GHOST_SystemWin32.cpp
index 625a34aa142..b97bf1d089c 100644
--- a/intern/ghost/intern/GHOST_SystemWin32.cpp
+++ b/intern/ghost/intern/GHOST_SystemWin32.cpp
@@ -316,11 +316,21 @@ GHOST_IContext *GHOST_SystemWin32::createOffscreenContext()
 
 	GHOST_Context *context;
 
+	HWND wnd = CreateWindowA("STATIC",
+		"BlenderGLEW",
+		WS_OVERLAPPEDWINDOW | WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
+		0, 0, 64, 64,
+		NULL, NULL,
+		GetModuleHandle(NULL), NULL
+	);
+
+	HDC  mHDC = GetDC(wnd);
+
 #if defined(WITH_GL_PROFILE_CORE)
 	for (int minor = 5; minor >= 0; --minor) {
 			context = new GHOST_ContextWGL(
 			    false, true, 0,
-			    NULL, NULL,
+			    wnd, mHDC,
 			    WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
 			    4, minor,
 			    (debug_context ? WGL_CONTEXT_DEBUG_BIT_ARB : 0),
@@ -336,7 +346,7 @@ GHOST_IContext *GHOST_SystemWin32::createOffscreenContext()
 
 		context = new GHOST_ContextWGL(
 		    false, true, 0,
-		    NULL, NULL,
+		    wnd, mHDC,
 		    WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
 		    3, 3,
 		    (debug_context ? WGL_CONTEXT_DEBUG_BIT_ARB : 0),