added & renamed some constants; fixed & added some doxygen comments; cleaned up the dirty screen code a bit (this should also fix a bug in V1/V2 games where part of the screen was not redrawn properly)

svn-id: r12118

5 files changed, 88 insertions, 80 deletions

diff --git a/scumm/camera.cpp b/scumm/camera.cpp
index 0357392ce9..c35a93a5ca 100644
--- a/scumm/camera.cpp
+++ b/scumm/camera.cpp
@@ -29,7 +29,7 @@ namespace Scumm {
 
 void ScummEngine::setCameraAtEx(int at) {
 	if (!(_features & GF_NEW_CAMERA)) {
-		camera._mode = CM_NORMAL;
+		camera._mode = kNormalCameraMode;
 		camera._cur.x = at;
 		setCameraAt(at, 0);
 		camera._movingToActor = false;
@@ -37,7 +37,7 @@ void ScummEngine::setCameraAtEx(int at) {
 }
 
 void ScummEngine::setCameraAt(int pos_x, int pos_y) {
-	if (camera._mode != CM_FOLLOW_ACTOR || abs(pos_x - camera._cur.x) > (_screenWidth / 2)) {
+	if (camera._mode != kFollowActorCameraMode || abs(pos_x - camera._cur.x) > (_screenWidth / 2)) {
 		camera._cur.x = pos_x;
 	}
 	camera._dest.x = pos_x;
@@ -89,12 +89,12 @@ void ScummEngine::setCameraFollows(Actor *a) {
 
 	int t, i;
 
-	camera._mode = CM_FOLLOW_ACTOR;
+	camera._mode = kFollowActorCameraMode;
 	camera._follows = a->number;
 
 	if (!a->isInCurrentRoom()) {
 		startScene(a->getRoom(), 0, 0);
-		camera._mode = CM_FOLLOW_ACTOR;
+		camera._mode = kFollowActorCameraMode;
 		camera._cur.x = a->_pos.x;
 		setCameraAt(camera._cur.x, 0);
 	}
@@ -174,7 +174,7 @@ void ScummEngine::moveCamera() {
 		return;
 	}
 
-	if (camera._mode == CM_FOLLOW_ACTOR) {
+	if (camera._mode == kFollowActorCameraMode) {
 		a = derefActor(camera._follows, "moveCamera");
 
 		actorx = a->_pos.x;
@@ -353,7 +353,7 @@ void ScummEngine::cameraMoved() {
 
 void ScummEngine::panCameraTo(int x, int y) {
 	camera._dest.x = x;
-	camera._mode = CM_PANNING;
+	camera._mode = kPanningCameraMode;
 	camera._movingToActor = false;
 }
 
@@ -373,7 +373,7 @@ void ScummEngine::actorFollowCamera(int act) {
 /*
 		// MI1 compatibilty
 		if (act == 0) {
-			camera._mode = CM_NORMAL;
+			camera._mode = kNormalCameraMode;
 			camera._follows = 0;
 			camera._movingToActor = false;
 			return;
diff --git a/scumm/gfx.cpp b/scumm/gfx.cpp
index 8a124e245b..583e52698a 100644
--- a/scumm/gfx.cpp
+++ b/scumm/gfx.cpp
@@ -250,9 +250,9 @@ void ScummEngine::initScreens(int a, int b, int w, int h) {
 			initVirtScreen(3, 0, 80, _screenWidth, 13, false, false);
 		}
 	}
-	initVirtScreen(0, 0, b, _screenWidth, h - b, true, true);
-	initVirtScreen(1, 0, 0, _screenWidth, b, false, false);
-	initVirtScreen(2, 0, h, _screenWidth, _screenHeight - h, false, false);
+	initVirtScreen(kMainVirtScreen, 0, b, _screenWidth, h - b, true, true);
+	initVirtScreen(kTextVirtScreen, 0, 0, _screenWidth, b, false, false);
+	initVirtScreen(kVerbVirtScreen, 0, h, _screenWidth, _screenHeight - h, false, false);
 
 	_screenB = b;
 	_screenH = h;
@@ -371,32 +371,34 @@ void ScummEngine::updateDirtyRect(int virt, int left, int right, int top, int bo
 	}
 }
 
+/**
+ * Update all dirty screen areas. This method blits all of the internal engine
+ * graphics to the actual display, as needed. In addition, the 'shaking'
+ * code in the backend is controlled from here.
+ */
 void ScummEngine::drawDirtyScreenParts() {
-	int i;
-	VirtScreen *vs;
-	byte *src;
-
-	updateDirtyScreen(2);
+	// Update verbs
+	updateDirtyScreen(kVerbVirtScreen);
+	
+	// In V1-V3, update the conversation area (at the top of the screen)
 	if (_version <= 3)
-		updateDirtyScreen(1);
-
-	if (camera._last.x == camera._cur.x && (camera._last.y == camera._cur.y || !(_features & GF_NEW_CAMERA))) {
-		updateDirtyScreen(0);
+		updateDirtyScreen(kTextVirtScreen);
+
+	// Update game area ("stage")
+	if (camera._last.x != camera._cur.x || (_features & GF_NEW_CAMERA && (camera._cur.y != camera._last.y))) {
+		// Camera moved: redraw everything
+		// Small side note: most of our GFX code relies on this identity:
+		// gdi._numStrips * 8 == _screenWidth == vs->width
+		VirtScreen *vs = &virtscr[kMainVirtScreen];
+		gdi.drawStripToScreen(vs, 0, vs->width, 0, vs->height);
+		vs->setDirtyRange(vs->height, 0);
 	} else {
-		vs = &virtscr[0];
-
-		src = vs->screenPtr + vs->xstart + _screenTop * _screenWidth;
-		_system->copy_rect(src, _screenWidth, 0, vs->topline, _screenWidth, vs->height - _screenTop);
-
-		for (i = 0; i < gdi._numStrips; i++) {
-			vs->tdirty[i] = vs->height;
-			vs->bdirty[i] = 0;
-		}
+		updateDirtyScreen(kMainVirtScreen);
 	}
 
-	/* Handle shaking */
+	// Handle shaking
 	if (_shakeEnabled) {
-		_shakeFrame = (_shakeFrame + 1) & (NUM_SHAKE_POSITIONS - 1);
+		_shakeFrame = (_shakeFrame + 1) % NUM_SHAKE_POSITIONS;
 		_system->set_shake_pos(shake_positions[_shakeFrame]);
 	} else if (!_shakeEnabled &&_shakeFrame != 0) {
 		_shakeFrame = 0;
@@ -409,44 +411,38 @@ void ScummEngine::updateDirtyScreen(int slot) {
 }
 
 /**
- * Blit the data from the given VirtScreen to the display. If the camera moved,
+ * Blit the dirty data from the given VirtScreen to the display. If the camera moved,
  * a full blit is done, otherwise only the visible dirty areas are updated.
  */
 void Gdi::updateDirtyScreen(VirtScreen *vs) {
+	// Do nothing for unused virtual screens
 	if (vs->height == 0)
 		return;
 
-	if (_vm->_features & GF_NEW_CAMERA && (_vm->camera._cur.y != _vm->camera._last.y)) {
-		drawStripToScreen(vs, 0, _numStrips * 8, 0, vs->height);
-	} else {
-		int i;
-		int start, w, top, bottom;
-
-		w = 8;
-		start = 0;
-
-		for (i = 0; i < _numStrips; i++) {
-			bottom = vs->bdirty[i];
-
-			if (bottom) {
-				top = vs->tdirty[i];
-				vs->tdirty[i] = vs->height;
-				vs->bdirty[i] = 0;
-				if (i != (_numStrips - 1) && vs->bdirty[i + 1] == bottom && vs->tdirty[i + 1] == top) {
-					// Simple optimizations: if two or more neighbouring strips form one bigger rectangle,
-					// blit them all at once.
-					w += 8;
-					continue;
-				}
-				// handle vertically scrolling rooms
-				if (_vm->_features & GF_NEW_CAMERA)
-					drawStripToScreen(vs, start * 8, w, 0, vs->height);
-				else
-					drawStripToScreen(vs, start * 8, w, top, bottom);
-				w = 8;
+	int i;
+	int w = 8;
+	int start = 0;
+
+	for (i = 0; i < _numStrips; i++) {
+		if (vs->bdirty[i]) {
+			const int bottom = vs->bdirty[i];
+			const int top = vs->tdirty[i];
+			vs->tdirty[i] = vs->height;
+			vs->bdirty[i] = 0;
+			if (i != (_numStrips - 1) && vs->bdirty[i + 1] == bottom && vs->tdirty[i + 1] == top) {
+				// Simple optimizations: if two or more neighbouring strips form one bigger rectangle,
+				// blit them all at once.
+				w += 8;
+				continue;
 			}
-			start = i + 1;
+			// handle vertically scrolling rooms
+			if (_vm->_features & GF_NEW_CAMERA)
+				drawStripToScreen(vs, start * 8, w, 0, vs->height);
+			else
+				drawStripToScreen(vs, start * 8, w, top, bottom);
+			w = 8;
 		}
+		start = i + 1;
 	}
 }
 
@@ -2257,7 +2253,7 @@ void ScummEngine::fadeOut(int effect) {
 		case 129:
 			// Just blit screen 0 to the display (i.e. display will be black)
 			vs->setDirtyRange(0, vs->height);
-			updateDirtyScreen(0);
+			updateDirtyScreen(kMainVirtScreen);
 			break;
 		case 134:
 			dissolveEffect(1, 1);
@@ -2341,7 +2337,7 @@ void ScummEngine::transitionEffect(int a) {
 				else
 					virtscr[0].bdirty[l] = (b + 1) * 8;
 			}
-			updateDirtyScreen(0);
+			updateDirtyScreen(kMainVirtScreen);
 		}
 
 		for (i = 0; i < 16; i++)
diff --git a/scumm/gfx.h b/scumm/gfx.h
index 5dc17a97f0..367f92b4fe 100644
--- a/scumm/gfx.h
+++ b/scumm/gfx.h
@@ -29,13 +29,15 @@ namespace Scumm {
 
 class ScummEngine;
 
-enum {					/** Camera modes */
-	CM_NORMAL = 1,
-	CM_FOLLOW_ACTOR = 2,
-	CM_PANNING = 3
+/** Camera modes */
+enum {
+	kNormalCameraMode = 1,
+	kFollowActorCameraMode = 2,
+	kPanningCameraMode = 3
 };
 
-struct CameraData {		/** Camera state data */
+/** Camera state data */
+struct CameraData {
 	Common::Point _cur;
 	Common::Point _dest;
 	Common::Point _accel;
@@ -45,7 +47,15 @@ struct CameraData {		/** Camera state data */
 	bool _movingToActor;
 };
 
-struct VirtScreen {		/** Virtual screen areas */
+/** Virtual screen identifiers */
+enum {
+	kMainVirtScreen = 0,	// The 'stage'
+	kTextVirtScreen = 1,	// In V1-V3 games: the area where text is printed
+	kVerbVirtScreen = 2		// The verb area
+};
+
+/** Virtual screen areas */
+struct VirtScreen {
 	int number;
 	uint16 topline;
 	uint16 width, height;
@@ -66,7 +76,8 @@ struct VirtScreen {		/** Virtual screen areas */
 	}
 };
 
-struct ColorCycle {		/** Palette cycles */
+/** Palette cycles */
+struct ColorCycle {
 	uint16 delay;
 	uint16 counter;
 	uint16 flags;
@@ -74,7 +85,8 @@ struct ColorCycle {		/** Palette cycles */
 	byte end;
 };
 
-struct BlastObject {		/** BlastObjects to draw */
+/** BlastObjects to draw */
+struct BlastObject {
 	uint16 number;
 	int16 posX, posY;
 	uint16 width, height;
@@ -190,14 +202,14 @@ public:
 // to get it fixed and so that really interested parties can experiment it.
 // It is NOT FIT FOR GENERAL USAGE! You have been warned.
 //
-// Doing this correctly will be quite some more complicated. Basically, with smooth
-// scrolling, the virtual screen strips don't match the display screen strips.
-// Hence we either have to draw partial strips - but that'd be rather cumbersome.
-// Or the much simple (and IMHO more elegant) solution is to simply use a screen pitch
-// that is 8 pixel wider than the real screen width, and always draw one strip more than 
-// needed to the backbuf. This will still require quite some code to be changed but
-// should otherwise be relatively easy to understand, and using VirtScreen::pitch
-// will actually clean up the code.
+// Doing this correctly will be complicated. Basically, with smooth scrolling,
+// the virtual screen strips don't match the display screen strips. Hence we
+// either have to draw partial strips (but that'd be rather cumbersome). Or the
+// alternative (and IMHO more elegant) solution is to simply use a screen pitch
+// that is 8 pixel wider than the real screen width, and always draw one strip
+// more than needed to the backbuf. This will still require quite some code to
+// be changed but should otherwise be relatively easy to understand, and using
+// VirtScreen::pitch will actually clean up the code.
 //
 // #define V7_SMOOTH_SCROLLING_HACK
 
diff --git a/scumm/script_v2.cpp b/scumm/script_v2.cpp
index 19a2b558f4..d21c844943 100644
--- a/scumm/script_v2.cpp
+++ b/scumm/script_v2.cpp
@@ -1411,7 +1411,7 @@ void ScummEngine_v2::o2_endCutscene() {
 	
 	if (_gameId == GID_MANIAC) {
 		camera._mode = (byte) vm.cutSceneData[3];
-		if (camera._mode == CM_FOLLOW_ACTOR) {
+		if (camera._mode == kFollowActorCameraMode) {
 			actorFollowCamera(VAR(VAR_EGO));
 		} else if (vm.cutSceneData[2] != _currentRoom) {
 			startScene(vm.cutSceneData[2], 0, 0);
diff --git a/scumm/scummvm.cpp b/scumm/scummvm.cpp
index 1072356ad3..ffb7b74942 100644
--- a/scumm/scummvm.cpp
+++ b/scumm/scummvm.cpp
@@ -2083,7 +2083,7 @@ void ScummEngine::startScene(int room, Actor *a, int objectNr) {
 		VAR(VAR_CAMERA_MAX_Y) = _roomHeight - (_screenHeight / 2);
 		setCameraAt(_screenWidth / 2, _screenHeight / 2);
 	} else {
-		camera._mode = CM_NORMAL;
+		camera._mode = kNormalCameraMode;
 		if (_version > 2)
 			camera._cur.x = camera._dest.x = _screenWidth / 2;
 		camera._cur.y = camera._dest.y = _screenHeight / 2;