SCI32: Fix bad palettes in Lighthouse when HQ video is enabled

In a couple of places, Lighthouse updates the renderer with screen
items for the next room before the room transition video plays.
This is normally fine when using the compositing video renderer
because the videos are drawn into new planes which occlude the
screen items, so the screen items are culled from the draw list
and do not submit their palettes. However, when in HQ video mode,
we currently force the overlay renderer, which was not blocking
screen items before forcing a frameOut, so the screen items'
palettes got submitted prematurely in this case and caused bad
rendering after the video finished playback.

Now, if we are forcing into the overlay code path, we still create
a blank plane behind the overlay before the forced frameOut in
order to correctly occlude screen items and keep them from
participating in rendering before they normally would.

Fixes Trac#10233, Trac#10235.

2 files changed, 25 insertions, 2 deletions

diff --git a/engines/sci/graphics/video32.cpp b/engines/sci/graphics/video32.cpp
index 91e48612d8..16884a1e9a 100644
--- a/engines/sci/graphics/video32.cpp
+++ b/engines/sci/graphics/video32.cpp
@@ -743,6 +743,20 @@ VMDPlayer::EventFlags VMDPlayer::checkForEvent(const EventFlags flags) {
 }
 
 void VMDPlayer::initOverlay() {
+	// Composited videos forced through the overlay renderer (due to HQ video
+	// mode) still need to occlude whatever is behind them in the renderer (as
+	// in composited mode) to prevent palette glitches caused by premature
+	// submission of occluded screen items (e.g. leaving the lava room sphere in
+	// the volcano in Lighthouse, the pic after the video finishes playing will
+	// be rendered with the wrong palette)
+	if (isNormallyComposited() && _planeIsOwned) {
+		_plane = new Plane(_drawRect, kPlanePicColored);
+		if (_priority) {
+			_plane->_priority = _priority;
+		}
+		g_sci->_gfxFrameout->addPlane(_plane);
+	}
+
 	// Make sure that any pending graphics changes from the game are submitted
 	// before starting playback, since if they aren't, and the video player
 	// yields back to the VM in the middle of playback, there may be a flash of
@@ -854,6 +868,11 @@ void VMDPlayer::submitPalette(const uint8 rawPalette[256 * 3]) const {
 }
 
 void VMDPlayer::closeOverlay() {
+	if (isNormallyComposited() && _planeIsOwned && _plane != nullptr) {
+		g_sci->_gfxFrameout->deletePlane(*_plane);
+		_plane = nullptr;
+	}
+
 #ifdef USE_RGB_COLOR
 	if (_hqVideoMode) {
 		if (endHQVideo()) {
diff --git a/engines/sci/graphics/video32.h b/engines/sci/graphics/video32.h
index cd4436f7e7..7b2cffa2ae 100644
--- a/engines/sci/graphics/video32.h
+++ b/engines/sci/graphics/video32.h
@@ -503,12 +503,16 @@ private:
 	 */
 	bool shouldUseCompositing() const {
 #ifdef USE_RGB_COLOR
-		return getSciVersion() == SCI_VERSION_3 && !shouldStartHQVideo();
+		return isNormallyComposited() && !shouldStartHQVideo();
 #else
-		return getSciVersion() == SCI_VERSION_3;
+		return isNormallyComposited();
 #endif
 	}
 
+	bool isNormallyComposited() const {
+		return getSciVersion() == SCI_VERSION_3;
+	}
+
 	void initOverlay();
 	void renderOverlay(const Graphics::Surface &nextFrame) const;
 	void closeOverlay();