# HG changeset patch
# User Michael Lutz <michi@icosahedron.de>
# Date 2021-04-24 22:43:38
# Node ID 3b1b500a06d6762502646b333394d04fb8fa3a2f
# Parent  b20f15e2e2767584df60cb5f896fd1a5e50fefcc

Fix: [OpenGL] Main loop expects to start with the video buffer unmapped. (#9100)

diff --git a/src/video/opengl.cpp b/src/video/opengl.cpp
--- a/src/video/opengl.cpp
+++ b/src/video/opengl.cpp
@@ -1154,6 +1154,7 @@ void *OpenGLBackend::GetVideoBuffer()
 #endif
 
 	if (!this->persistent_mapping_supported) {
+		assert(this->vid_buffer == nullptr);
 		_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->vid_pbo);
 		this->vid_buffer = _glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_READ_WRITE);
 	} else if (this->vid_buffer == nullptr) {
diff --git a/src/video/sdl2_opengl_v.cpp b/src/video/sdl2_opengl_v.cpp
--- a/src/video/sdl2_opengl_v.cpp
+++ b/src/video/sdl2_opengl_v.cpp
@@ -74,6 +74,8 @@ const char *VideoDriver_SDL_OpenGL::Star
 		this->Stop();
 		return "Can't get pointer to screen buffer";
 	}
+	/* Main loop expects to start with the buffer unmapped. */
+	this->ReleaseVideoPointer();
 
 	return nullptr;
 }
diff --git a/src/video/win32_v.cpp b/src/video/win32_v.cpp
--- a/src/video/win32_v.cpp
+++ b/src/video/win32_v.cpp
@@ -1311,6 +1311,8 @@ const char *VideoDriver_Win32OpenGL::Sta
 		_cur_resolution = old_res;
 		return "Can't get pointer to screen buffer";
 	}
+	/* Main loop expects to start with the buffer unmapped. */
+	this->ReleaseVideoPointer();
 
 	MarkWholeScreenDirty();