SCI32: Split out detection of features that cross SSCI versions

2 files changed, 36 insertions, 3 deletions

diff --git a/engines/sci/engine/features.h b/engines/sci/engine/features.h
index b2d40f400f..15c80a7277 100644
--- a/engines/sci/engine/features.h
+++ b/engines/sci/engine/features.h
@@ -82,6 +82,41 @@ public:
 	 * @return Graphics functions type, SCI_VERSION_2 / SCI_VERSION_2_1
 	 */
 	SciVersion detectSci21KernelType();
+
+	inline bool usesModifiedAudioAttenuation() const {
+		switch (g_sci->getGameId()) {
+		// Assuming MGDX uses modified attenuation since SQ6 does and it was
+		// released earlier, but not verified (Phar Lap Windows-only release)
+		case GID_MOTHERGOOSEHIRES:
+		case GID_PQ4:
+		case GID_SQ6:
+			return true;
+		case GID_KQ7:
+		case GID_QFG4:
+			// (1) KQ7 1.51 (SCI2.1early) uses the non-standard attenuation, but
+			// 2.00b (SCI2.1mid) does not
+			// (2) QFG4 CD is SCI2.1early; QFG4 floppy is SCI2 and does not use
+			// the SCI2.1 audio system
+			return getSciVersion() == SCI_VERSION_2_1_EARLY;
+		default:
+			return false;
+		}
+	}
+
+	inline bool hasTransparentPicturePlanes() const {
+		const SciGameId &gid = g_sci->getGameId();
+
+		// NOTE: MGDX is assumed to not have transparent picture planes since it
+		// was released before SQ6, but this has not been verified since it
+		// cannot be disassembled at the moment (Phar Lap Windows-only release)
+		return getSciVersion() >= SCI_VERSION_2_1_MIDDLE &&
+			gid != GID_SQ6 &&
+			gid != GID_MOTHERGOOSEHIRES;
+	}
+
+	inline bool hasNewPaletteCode() const {
+		return getSciVersion() >= SCI_VERSION_2_1_MIDDLE || g_sci->getGameId() == GID_KQ7;
+	}
 #endif
 
 	/**
diff --git a/engines/sci/engine/kgraphics32.cpp b/engines/sci/engine/kgraphics32.cpp
index 039373c387..d4377417a8 100644
--- a/engines/sci/engine/kgraphics32.cpp
+++ b/engines/sci/engine/kgraphics32.cpp
@@ -972,9 +972,7 @@ reg_t kPalVarySetVary(EngineState *s, int argc, reg_t *argv) {
 	int16 fromColor;
 	int16 toColor;
 
-	if ((getSciVersion() >= SCI_VERSION_2_1_MIDDLE || g_sci->getGameId() == GID_KQ7)
-		&& argc > 4) {
-
+	if (g_sci->_features->hasNewPaletteCode() && argc > 4) {
 		fromColor = argv[3].toSint16();
 		toColor = argv[4].toSint16();
 	} else {