Some more fixes to Gfx::palFade

svn-id: r28710

1 files changed, 17 insertions, 2 deletions

diff --git a/engines/saga/gfx.cpp b/engines/saga/gfx.cpp
index 31e730d8d2..6e5824c1b0 100644
--- a/engines/saga/gfx.cpp
+++ b/engines/saga/gfx.cpp
@@ -416,12 +416,27 @@ void Gfx::palFade(PalEntry *srcPal, int16 from, int16 to, int16 start, int16 num
 
 	// Exponential fade
 	fpercent = percent * percent;
+	fpercent = fpercent < 0.0 ? 0.0 : fpercent;
+	fpercent = fpercent > 1.0 ? 1.0 : fpercent;
+
+	// TODO: finish this (use from and to properly). The fpercent value will need to be
+	// correctly assigned, based on from and to. For now, only certain cases work correctly
+	if (from == 0 || to == 0) {
+		// This case works like palToBlack or blackToPal, so no changes are needed
+	} else if ((from / to == 2) || (to / from == 2)) {
+		// It's easy to use the current algorithm if we're trying to fade to half the value
+		fpercent /= 2;
+		if (from < to)
+			fpercent += 0.5;
+	} else {
+		// FIXME: In all other cases, throw a warning, as we'll fade out to/from black
+		if (percent == 0.0)
+			warning("Screen fading effect not supported yet, fading to/from black for now");
+	}
 
 	if (from > to)
 		fpercent = 1.0 - fpercent;
 
-	// TODO: finish this (it always fades to black!) -> use from and to
-
 	// Use the correct percentage change per frame for each palette entry
 	for (i = 0, ppal = _currentPal; i < PAL_ENTRIES; i++, ppal += 4) {
 		if (i < start || i >= start + numColors)