diff.diff

diff --git a/src/video/opengl.cpp b/src/video/opengl.cpp
index 26f6f4b4d..b2852bbf8 100644
--- a/src/video/opengl.cpp
+++ b/src/video/opengl.cpp
@@ -1101,8 +1101,8 @@ void *OpenGLBackend::GetVideoBuffer()
 #endif
 
 	if (!this->persistent_mapping_supported) {
-		_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->vid_pbo);
-		this->vid_buffer = _glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_READ_WRITE);
+		if (this->vid_buffer == nullptr)
+			this->vid_buffer = new unsigned char[_screen.pitch * _screen.height * BlitterFactory::GetCurrentBlitter()->GetScreenDepth() / 8];
 	} else if (this->vid_buffer == nullptr) {
 		_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->vid_pbo);
 		this->vid_buffer = _glMapBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, _screen.pitch * _screen.height * BlitterFactory::GetCurrentBlitter()->GetScreenDepth() / 8, GL_MAP_READ_BIT | GL_MAP_WRITE_BIT | GL_MAP_PERSISTENT_BIT | GL_MAP_COHERENT_BIT);
@@ -1124,8 +1124,8 @@ uint8 *OpenGLBackend::GetAnimBuffer()
 #endif
 
 	if (!this->persistent_mapping_supported) {
-		_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->anim_pbo);
-		this->anim_buffer = _glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_READ_WRITE);
+		if (this->anim_buffer == nullptr)
+			this->anim_buffer = new unsigned char[_screen.pitch * _screen.height];
 	} else if (this->anim_buffer == nullptr) {
 		_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->anim_pbo);
 		this->anim_buffer = _glMapBufferRange(GL_PIXEL_UNPACK_BUFFER, 0, _screen.pitch * _screen.height, GL_MAP_READ_BIT | GL_MAP_WRITE_BIT | GL_MAP_PERSISTENT_BIT | GL_MAP_COHERENT_BIT);
@@ -1142,10 +1142,13 @@ void OpenGLBackend::ReleaseVideoBuffer(const Rect &update_rect)
 {
 	assert(this->vid_pbo != 0);
 
-	_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->vid_pbo);
+	unsigned char* mem = 0;
+
 	if (!this->persistent_mapping_supported) {
-		_glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
-		this->vid_buffer = nullptr;
+		mem = (unsigned char*)this->vid_buffer;
+		_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+	} else {
+		_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->vid_pbo);
 	}
 
 #ifndef NO_GL_BUFFER_SYNC
@@ -1162,11 +1165,11 @@ void OpenGLBackend::ReleaseVideoBuffer(const Rect &update_rect)
 		_glPixelStorei(GL_UNPACK_ROW_LENGTH, _screen.pitch);
 		switch (BlitterFactory::GetCurrentBlitter()->GetScreenDepth()) {
 			case 8:
-				_glTexSubImage2D(GL_TEXTURE_2D, 0, update_rect.left, update_rect.top, update_rect.right - update_rect.left, update_rect.bottom - update_rect.top, GL_RED, GL_UNSIGNED_BYTE, (GLvoid *)(size_t)(update_rect.top * _screen.pitch + update_rect.left));
+				_glTexSubImage2D(GL_TEXTURE_2D, 0, update_rect.left, update_rect.top, update_rect.right - update_rect.left, update_rect.bottom - update_rect.top, GL_RED, GL_UNSIGNED_BYTE, (GLvoid *)(size_t)(mem + update_rect.top * _screen.pitch + update_rect.left));
 				break;
 
 			default:
-				_glTexSubImage2D(GL_TEXTURE_2D, 0, update_rect.left, update_rect.top, update_rect.right - update_rect.left, update_rect.bottom - update_rect.top, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, (GLvoid *)(size_t)(update_rect.top * _screen.pitch * 4 + update_rect.left * 4));
+				_glTexSubImage2D(GL_TEXTURE_2D, 0, update_rect.left, update_rect.top, update_rect.right - update_rect.left, update_rect.bottom - update_rect.top, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, (GLvoid *)(size_t)(mem + update_rect.top * _screen.pitch * 4 + update_rect.left * 4));
 				break;
 		}
 
@@ -1184,10 +1187,14 @@ void OpenGLBackend::ReleaseAnimBuffer(const Rect &update_rect)
 {
 	if (this->anim_pbo == 0) return;
 
-	_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->anim_pbo);
+	unsigned char* mem = 0;
+
 	if (!this->persistent_mapping_supported) {
-		_glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
-		this->anim_buffer = nullptr;
+		mem = (unsigned char*)this->anim_buffer;
+		_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+	}
+	else {
+		_glBindBuffer(GL_PIXEL_UNPACK_BUFFER, this->anim_pbo);
 	}
 
 #ifndef NO_GL_BUFFER_SYNC
@@ -1202,7 +1209,7 @@ void OpenGLBackend::ReleaseAnimBuffer(const Rect &update_rect)
 		_glActiveTexture(GL_TEXTURE0);
 		_glBindTexture(GL_TEXTURE_2D, this->anim_texture);
 		_glPixelStorei(GL_UNPACK_ROW_LENGTH, _screen.pitch);
-		_glTexSubImage2D(GL_TEXTURE_2D, 0, update_rect.left, update_rect.top, update_rect.right - update_rect.left, update_rect.bottom - update_rect.top, GL_RED, GL_UNSIGNED_BYTE, (GLvoid *)(size_t)(update_rect.top * _screen.pitch + update_rect.left));
+		_glTexSubImage2D(GL_TEXTURE_2D, 0, update_rect.left, update_rect.top, update_rect.right - update_rect.left, update_rect.bottom - update_rect.top, GL_RED, GL_UNSIGNED_BYTE, (GLvoid *)(size_t)(mem + update_rect.top * _screen.pitch + update_rect.left));
 
 #ifndef NO_GL_BUFFER_SYNC
 		if (this->persistent_mapping_supported) this->sync_anim_mapping = _glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);