2 files changed, 16 insertions, 12 deletions
diff --git a/engines/sci/graphics/frameout.cpp b/engines/sci/graphics/frameout.cpp
index cb777301b0..4ec91dc6ad 100644
--- a/engines/sci/graphics/frameout.cpp
+++ b/engines/sci/graphics/frameout.cpp
@@ -492,7 +492,7 @@ void GfxFrameout::kernelAddPicAt(const reg_t planeObject, const GuiResourceId pi
 #pragma mark -
 #pragma mark Rendering
 
-void GfxFrameout::frameOut(const bool shouldShowBits, const Common::Rect &rect) {
+void GfxFrameout::frameOut(const bool shouldShowBits, const Common::Rect &eraseRect) {
 // TODO: Robot
 //	if (_robot != nullptr) {
 //		_robot.doRobot();
@@ -510,7 +510,7 @@ void GfxFrameout::frameOut(const bool shouldShowBits, const Common::Rect &rect)
 		remapMarkRedraw();
 	}
 
-	calcLists(screenItemLists, eraseLists, rect);
+	calcLists(screenItemLists, eraseLists, eraseRect);
 
 	for (ScreenItemListList::iterator list = screenItemLists.begin(); list != screenItemLists.end(); ++list) {
 		list->sort();
@@ -597,14 +597,17 @@ void GfxFrameout::calcLists(ScreenItemListList &drawLists, EraseListList &eraseL
 	RectList rectlist;
 	Common::Rect outRects[4];
 
+// NOTE: The third rectangle parameter is only ever given a non-empty rect
+// by VMD code, via `frameOut`
+void GfxFrameout::calcLists(ScreenItemListList &drawLists, EraseListList &eraseLists, const Common::Rect &eraseRect) {
 	int deletedPlaneCount = 0;
 	bool addedToRectList = false;
 	int planeCount = _planes.size();
 	bool foundTransparentPlane = false;
 
-	if (!calcRect.isEmpty()) {
-		addedToRectList = true;
-		rectlist.add(calcRect);
+	if (!eraseRect.isEmpty()) {
+		addedToEraseList = true;
+		rectlist.add(eraseRect);
 	}
 
 	for (int outerPlaneIndex = 0; outerPlaneIndex < planeCount; ++outerPlaneIndex) {
@@ -885,8 +888,6 @@ void GfxFrameout::palMorphFrameOut(const int8 *styleRanges, const ShowStyleEntry
 	_showList.add(rect);
 	showBits();
 
-	Common::Rect calcRect(0, 0);
-
 	// NOTE: The original engine allocated these as static arrays of 100
 	// pointers to ScreenItemList / RectList
 	ScreenItemListList screenItemLists;
@@ -899,7 +900,7 @@ void GfxFrameout::palMorphFrameOut(const int8 *styleRanges, const ShowStyleEntry
 		remapMarkRedraw();
 	}
 
-	calcLists(screenItemLists, eraseLists, calcRect);
+	calcLists(screenItemLists, eraseLists);
 	for (ScreenItemListList::iterator list = screenItemLists.begin(); list != screenItemLists.end(); ++list) {
 		list->sort();
 	}
@@ -959,7 +960,7 @@ void GfxFrameout::palMorphFrameOut(const int8 *styleRanges, const ShowStyleEntry
 		remapMarkRedraw();
 	}
 
-	calcLists(screenItemLists, eraseLists, calcRect);
+	calcLists(screenItemLists, eraseLists);
 	for (ScreenItemListList::iterator list = screenItemLists.begin(); list != screenItemLists.end(); ++list) {
 		list->sort();
 	}
diff --git a/engines/sci/graphics/frameout.h b/engines/sci/graphics/frameout.h
index 0be5aece1e..e736872773 100644
--- a/engines/sci/graphics/frameout.h
+++ b/engines/sci/graphics/frameout.h
@@ -376,8 +376,10 @@ private:
 	 * over the entire screen for rendering the next frame.
 	 * The draw and erase lists in `drawLists` and
 	 * `eraseLists` each represent one plane on the screen.
+	 * The optional `eraseRect` argument allows a specific
+	 * area of the screen to be erased.
 	 */
-	void calcLists(ScreenItemListList &drawLists, EraseListList &eraseLists, const Common::Rect &calcRect);
+	void calcLists(ScreenItemListList &drawLists, EraseListList &eraseLists, const Common::Rect &eraseRect = Common::Rect());
 
 	/**
 	 * Erases the areas in the given erase list from the
@@ -430,9 +432,10 @@ public:
 	/**
 	 * Updates the internal screen buffer for the next
 	 * frame. If `shouldShowBits` is true, also sends the
-	 * buffer to hardware.
+	 * buffer to hardware. If `eraseRect` is non-empty,
+	 * it is added to the erase list for this frame.
 	 */
-	void frameOut(const bool shouldShowBits, const Common::Rect &rect = Common::Rect());
+	void frameOut(const bool shouldShowBits, const Common::Rect &eraseRect = Common::Rect());
 
 	/**
 	 * Modifies the raw pixel data for the next frame with