SCI/newgui: changed dithering logic, otherwise colors combined with black wouldnt get undithered correctly

svn-id: r44762

2 files changed, 10 insertions, 11 deletions

diff --git a/engines/sci/gui/gui_palette.cpp b/engines/sci/gui/gui_palette.cpp
index d979491d1d..5c2bfa6c01 100644
--- a/engines/sci/gui/gui_palette.cpp
+++ b/engines/sci/gui/gui_palette.cpp
@@ -144,7 +144,7 @@ bool SciGuiPalette::setAmiga() {
 
 void SciGuiPalette::setEGA() {
 	int i;
-	byte color1, color2;
+	byte color, color1, color2;
 	_sysPalette.colors[1].r  = 0x000; _sysPalette.colors[1].g  = 0x000; _sysPalette.colors[1].b  = 0x0AA;
 	_sysPalette.colors[2].r  = 0x000; _sysPalette.colors[2].g  = 0x0AA; _sysPalette.colors[2].b  = 0x000;
 	_sysPalette.colors[3].r  = 0x000; _sysPalette.colors[3].g  = 0x0AA; _sysPalette.colors[3].b  = 0x0AA;
@@ -165,12 +165,13 @@ void SciGuiPalette::setEGA() {
 	}
 	// Now setting colors 16-254 to the correct mix colors that occur when not doing a dithering run on
 	//  finished pictures
-	for (i = 16; i <= 254; i++) {
+	for (i = 0x10; i <= 0xFE; i++) {
 		_sysPalette.colors[i].used = 1;
+		color ^= i << 4;
 		color1 = i & 0x0F; color2 = i >> 4;
-		_sysPalette.colors[i].r = (_sysPalette.colors[color1].r >> 1) + (_sysPalette.colors[color2].r >> 1);
-		_sysPalette.colors[i].g = (_sysPalette.colors[color1].g >> 1) + (_sysPalette.colors[color2].g >> 1);
-		_sysPalette.colors[i].b = (_sysPalette.colors[color1].b >> 1) + (_sysPalette.colors[color2].b >> 1);
+		_sysPalette.colors[color].r = (_sysPalette.colors[color1].r >> 1) + (_sysPalette.colors[color2].r >> 1);
+		_sysPalette.colors[color].g = (_sysPalette.colors[color1].g >> 1) + (_sysPalette.colors[color2].g >> 1);
+		_sysPalette.colors[color].b = (_sysPalette.colors[color1].b >> 1) + (_sysPalette.colors[color2].b >> 1);
 	}
 	setOnScreen();
 }
diff --git a/engines/sci/gui/gui_screen.cpp b/engines/sci/gui/gui_screen.cpp
index e2da6fd072..555387e537 100644
--- a/engines/sci/gui/gui_screen.cpp
+++ b/engines/sci/gui/gui_screen.cpp
@@ -224,7 +224,7 @@ void SciGuiScreen::setPalette(GuiPalette*pal) {
 // Currently not really done, its supposed to be possible to only dither _visualScreen
 void SciGuiScreen::dither() {
 	int y, x;
-	byte color, ditheredColor;
+	byte color;
 	byte *screenPtr = _visualScreen;
 	byte *displayPtr = _displayScreen;
 
@@ -233,12 +233,10 @@ void SciGuiScreen::dither() {
 			color = *screenPtr;
 			if (color & 0xF0) {
 				color ^= color << 4;
-				ditheredColor = ((x^y) & 1) ? color >> 4 : color & 0x0F;
-				*screenPtr = ditheredColor;
-				if (_unditherState)
+				color = ((x^y) & 1) ? color >> 4 : color & 0x0F;
+				*screenPtr = color;
+				if (!_unditherState)
 					*displayPtr = color;
-				else
-					*displayPtr = ditheredColor;
 			}
 			screenPtr++; displayPtr++;
 		}