renamed unkVirtScreen4 to fadeToBlackEffect; fixed graphic transition glitch (#551584)

svn-id: r4294

5 files changed, 14 insertions, 9 deletions

diff --git a/gfx.cpp b/gfx.cpp
index 4b654ae231..8ba83cc8fa 100644
--- a/gfx.cpp
+++ b/gfx.cpp
@@ -555,13 +555,14 @@ void Scumm::moveMemInPalRes(int start, int end, byte direction)
 	}
 }
 
-void Scumm::unkVirtScreen4(int a)
+void Scumm::fadeToBlackEffect(int a)
 {
 	VirtScreen *vs;
 
 	setDirtyRange(0, 0, 0);
 	if (!(_features & GF_AFTER_V7))
 		camera._last.x = camera._cur.x;
+
 	if (!_screenEffectFlag)
 		return;
 	_screenEffectFlag = false;
@@ -569,10 +570,12 @@ void Scumm::unkVirtScreen4(int a)
 	if (a == 0)
 		return;
 
+	// Fill screen 0 with black
 	vs = &virtscr[0];
 	gdi._backbuff_ptr = vs->screenPtr + vs->xstart;
 	memset(gdi._backbuff_ptr, 0, vs->size);
 
+	// Fade to black with the specified effect, if any.
 	switch (a) {
 	case 1:
 	case 2:
@@ -583,8 +586,9 @@ void Scumm::unkVirtScreen4(int a)
 		unkScreenEffect6();
 		break;
 	case 129:
-		//setDirtyRange(0, 0, vs->height);
-		//updateDirtyScreen(0);
+		// Just blit screen 0 to the display (i.e. display will be black)
+		setDirtyRange(0, 0, vs->height);
+		updateDirtyScreen(0);
 		/* XXX: EGA_proc4(0); */
 //		warning("EGA_proc4");				/* FIXME */
 		break;
@@ -595,7 +599,7 @@ void Scumm::unkVirtScreen4(int a)
 		unkScreenEffect5(1);
 		break;
 	default:
-		warning("unkVirtScreen4: default case %d", a);
+		warning("fadeToBlackEffect: default case %d", a);
 	}
 }
 
@@ -1759,6 +1763,7 @@ static const byte screen_eff7_table3[4] = {
 	13, 25, 25, 25
 };
 
+/* Transition effect */
 void Scumm::unkScreenEffect7(int a)
 {
 	int tab_1[16];
diff --git a/saveload.cpp b/saveload.cpp
index 8855623413..1c3eb44291 100644
--- a/saveload.cpp
+++ b/saveload.cpp
@@ -127,8 +127,8 @@ bool Scumm::loadState(int slot, bool compat)
 	gdi._mask_left = -1;
 
 	initScreens(0, 0, 320, 200);
-	_screenEffectFlag = 1;
-	unkVirtScreen4(129);
+	_screenEffectFlag = true;
+	fadeToBlackEffect(129);
 
 	initScreens(0, sb, 320, sh);
 
diff --git a/script_v2.cpp b/script_v2.cpp
index 4a25d761dd..f4dc5edf1c 100644
--- a/script_v2.cpp
+++ b/script_v2.cpp
@@ -2776,7 +2776,7 @@ void Scumm::o6_miscOps()
 			grabCursor(args[1], args[2], args[3], args[4]);
 			break;
 		case 5:
-			unkVirtScreen4(args[1]);
+			fadeToBlackEffect(args[1]);
 			break;
 		case 6:
 			_fullRedraw = 1;
diff --git a/scumm.h b/scumm.h
index 432b631297..4d9e8e2e06 100644
--- a/scumm.h
+++ b/scumm.h
@@ -1212,7 +1212,7 @@ public:
 	void updateDirtyScreen(int slot);
 
 	VirtScreen *findVirtScreen(int y);
-	void unkVirtScreen4(int a);
+	void fadeToBlackEffect(int a);
 	static void setVirtscreenDirty(VirtScreen *vs, int left, int top, int right, int bottom);
 
 	void screenEffect(int effect);
diff --git a/scummvm.cpp b/scummvm.cpp
index d610997324..a80a2e97a7 100644
--- a/scummvm.cpp
+++ b/scummvm.cpp
@@ -374,7 +374,7 @@ void Scumm::startScene(int room, Actor * a, int objectNr)
 
 	clearMsgQueue();
 
-	unkVirtScreen4(_switchRoomEffect2);
+	fadeToBlackEffect(_switchRoomEffect2);
 	_newEffect = _switchRoomEffect;
 
 	if (_currentScript != 0xFF) {