Implemented relative animations.

In these animations, each sprite can specify a relative shift with respect
to the previous sprite.  Moving animations (such as walking of the dragon)
are easily described in this framework.  I have sort of hacked their support
and it seems to work.

The current walking code does not interact with the new code yet, but it will
be easy to do.

svn-id: r45712

1 files changed, 40 insertions, 9 deletions

diff --git a/engines/draci/animation.cpp b/engines/draci/animation.cpp
index 674e2473df..9d56c89674 100644
--- a/engines/draci/animation.cpp
+++ b/engines/draci/animation.cpp
@@ -33,6 +33,7 @@ Animation::Animation(DraciEngine *vm, int index) : _vm(vm) {
 	_id = kUnused;
 	_index = index;
 	_z = 0;
+	clearShift();
 	_displacement = kNoDisplacement;
 	_playing = false;
 	_looping = false;
@@ -56,6 +57,13 @@ void Animation::setRelative(int relx, int rely) {
 	_displacement.relY = rely;
 }
 
+Displacement Animation::getCurrentFrameDisplacement() const {
+	Displacement dis = _displacement;
+	dis.relX += (int) (dis.extraScaleX * _shift.x);
+	dis.relY += (int) (dis.extraScaleY * _shift.y);
+	return dis;
+}
+
 void Animation::setLooping(bool looping) {
 	_looping = looping;
 	debugC(7, kDraciAnimationDebugLevel, "Setting looping to %d on animation %d",
@@ -67,8 +75,8 @@ void Animation::markDirtyRect(Surface *surface) const {
 		return;
 
 	// Fetch the current frame's rectangle
-	Drawable *frame = _frames[_currentFrame];
-	Common::Rect frameRect = frame->getRect(_displacement);
+	const Drawable *frame = getConstCurrentFrame();
+	Common::Rect frameRect = frame->getRect(getCurrentFrameDisplacement());
 
 	// Mark the rectangle dirty on the surface
 	surface->markDirtyRect(frameRect);
@@ -79,7 +87,7 @@ void Animation::nextFrame(bool force) {
 	if (getFrameCount() == 0 || !_playing)
 		return;
 
-	Drawable *frame = _frames[_currentFrame];
+	const Drawable *frame = getConstCurrentFrame();
 	Surface *surface = _vm->_screen->getSurface();
 
 	if (force || (_tick + frame->getDelay() <= _vm->_system->getMillis())) {
@@ -92,7 +100,12 @@ void Animation::nextFrame(bool force) {
 			// Mark old frame dirty so it gets deleted
 			markDirtyRect(surface);
 
+			_shift.x += _relativeShifts[_currentFrame].x;
+			_shift.y += _relativeShifts[_currentFrame].y;
 			_currentFrame = nextFrameNum();
+			if (!_currentFrame) {
+				clearShift();	// TODO: don't do that, but rather let the animation fly away when needed.
+			}
 			_tick = _vm->_system->getMillis();
 
 			// Fetch new frame and mark it dirty
@@ -123,13 +136,15 @@ void Animation::drawFrame(Surface *surface) {
 	if (_frames.size() == 0 || !_playing)
 		return;
 
-	const Drawable *frame = _frames[_currentFrame];
+	const Drawable *frame = getConstCurrentFrame();
 
 	if (_id == kOverlayImage) {
+		// No displacement or relative animations is supported.
 		frame->draw(surface, false, 0, 0);
 	} else {
-		// Draw frame
-		frame->drawReScaled(surface, false, _displacement);
+		// Draw frame: first shifted by the relative shift and then
+		// scaled/shifted by the given displacement.
+		frame->drawReScaled(surface, false, getCurrentFrameDisplacement());
 	}
 
 	const SoundSample *sample = _samples[_currentFrame];
@@ -164,6 +179,15 @@ void Animation::setScaleFactors(double scaleX, double scaleY) {
 void Animation::addFrame(Drawable *frame, const SoundSample *sample) {
 	_frames.push_back(frame);
 	_samples.push_back(sample);
+	_relativeShifts.push_back(Common::Point(0, 0));
+}
+
+void Animation::makeLastFrameRelative(int x, int y) {
+	_relativeShifts.back() = Common::Point(x, y);
+}
+
+void Animation::clearShift() {
+	_shift = Common::Point(0, 0);
 }
 
 void Animation::replaceFrame(int i, Drawable *frame, const SoundSample *sample) {
@@ -171,6 +195,11 @@ void Animation::replaceFrame(int i, Drawable *frame, const SoundSample *sample)
 	_samples[i] = sample;
 }
 
+const Drawable *Animation::getConstCurrentFrame() const {
+	// If there are no frames stored, return NULL
+	return _frames.size() > 0 ? _frames[_currentFrame] : NULL;
+}
+
 Drawable *Animation::getCurrentFrame() {
 	// If there are no frames stored, return NULL
 	return _frames.size() > 0 ? _frames[_currentFrame] : NULL;
@@ -202,6 +231,7 @@ void Animation::deleteFrames() {
 		delete _frames[i];
 		_frames.pop_back();
 	}
+	_relativeShifts.clear();
 	_samples.clear();
 }
 
@@ -280,6 +310,7 @@ void AnimationManager::stop(int id) {
 
 		// Reset the animation to the beginning
 		anim->setCurrentFrame(0);
+		anim->clearShift();
 
 		debugC(3, kDraciAnimationDebugLevel, "Stopping animation %d...", id);
 	}
@@ -499,19 +530,19 @@ int AnimationManager::getTopAnimationID(int x, int y) const {
 			continue;
 		}
 
-		const Drawable *frame = anim->getCurrentFrame();
+		const Drawable *frame = anim->getConstCurrentFrame();
 
 		if (frame == NULL) {
 			continue;
 		}
 
-		if (frame->getRect(anim->getDisplacement()).contains(x, y)) {
+		if (frame->getRect(anim->getCurrentFrameDisplacement()).contains(x, y)) {
 			if (frame->getType() == kDrawableText) {
 
 				retval = anim->getID();
 
 			} else if (frame->getType() == kDrawableSprite &&
-					   reinterpret_cast<const Sprite *>(frame)->getPixel(x, y, anim->getDisplacement()) != transparent) {
+					   reinterpret_cast<const Sprite *>(frame)->getPixel(x, y, anim->getCurrentFrameDisplacement()) != transparent) {
 
 				retval = anim->getID();
 			}