SCI32: Implement plane transitions (kSetShowStyle and kSetScroll)

This commit implements all of the known plane transitions from
SCI2 through SCI2.1mid games. Because kSetShowStyle is always
called indirectly via the Styler game script, it is difficult to
find all the places where transitions are used. As such,
transitions that appeared to never be used have been added as
stubs which will trigger a game crash with a message to report
what was being done, so any missed transition types can be
identified quickly and then implemented.

1 files changed, 3 insertions, 3 deletions

diff --git a/engines/sci/graphics/plane32.cpp b/engines/sci/graphics/plane32.cpp
index 6b05b2d98a..cb6ec74e8f 100644
--- a/engines/sci/graphics/plane32.cpp
+++ b/engines/sci/graphics/plane32.cpp
@@ -194,11 +194,11 @@ void Plane::addPicInternal(const GuiResourceId pictureId, const Common::Point *p
 	_type = transparent ? kPlaneTypeTransparentPicture : kPlaneTypePicture;
 }
 
-void Plane::addPic(const GuiResourceId pictureId, const Common::Point &position, const bool mirrorX) {
+GuiResourceId Plane::addPic(const GuiResourceId pictureId, const Common::Point &position, const bool mirrorX) {
+	GuiResourceId oldPictureId = _pictureId;
 	deletePic(pictureId);
 	addPicInternal(pictureId, &position, mirrorX);
-	// NOTE: In SCI engine this method returned the pictureId of the
-	// plane, but this return value was never used
+	return oldPictureId;
 }
 
 void Plane::changePic() {