Handling CGPoints / Waypoints « cocos2d for iPhone

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Handling CGPoints / Waypoints

(10 posts) (8 voices)

Started 1 year ago by pagex
Latest reply from cocos2dbeginner

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pagex
Member

Does anyone know of the best way to take a constantly changing set of CGPoints / waypoints and pass them to multiple sub-classed CCSprites which then determines the path/direction the sprite is to move on? Each sprite has it's own speed setting such as 250 pixels per second..

I've gone through many different versions of this where I'm passing the sprite the complete set of points, or a single point, etc etc and just can't get the timing right....

Looking for suggestions, ideas and/or inspiration... Thanks in advance.

Posted 1 year ago #
robodude666
Member

If each one of those CCSprites uses the same exact set of points, you could create a Singleton class that holds those points for you. Then simply have your children of CCSprite access the points via that Singleton.

Alternatively, you could loop through all children on a particular layer. If they are a CCSprite you want to know about this data then pass it to them via a synthesized method, or an instanced method if you need to manipulate it somehow.

Alternatively, if you are trying to move a CCSprite along a path possibly see if you could form that path to a Bezier Curve and simply use CCBezierBy to animate the sprite along that path. As far as I know, there is no current way to make a Sprite move along a specific path of CGPoints.

-robodude666

Posted 1 year ago #
pagex
Member

The best example I can think of as far as the mechanics are concerened would be a classic open path tower defense game where each sprite starts in the same location and moves towards the same target... but may have to change course and start down a new path at any moment in time before reaching it's destination. So I guess you could say the path is unique to each sprite but generated by an upper level class.

The thing that is tripping me up is how to best handle Actions, Positions, Timing, Speed, and what class exactly should be responsible for looping through the waypoints to manage those variables in the first place... looping through every sprite and set of waypoints seems wasteful as opposed to say... a scheduled tick that simply tracks LastPoint / NextPoint while taking time and distance into consideration.

Posted 1 year ago #
patrickC
Member

I did something somewhat similar for the AI driving in my first game, Mini Taxi.
I created a very simple struct containing a CGPoint and two pointers to nextPoint and previousPoint.
I then created a very simple level editor in QT and "drew" the paths the AI could follow by creating a series of inter-connected points on a grid.
I then parse this in game in the struct array, place an AI vehicle on one of my "node points" and send it on it's way.
In the normal tick/update method of the game I loop through the vehicles, which simply "aim" torwards nextPoint until they reach it, and then start aiming for the point after that, and so on.

If you wanted multiple splits you could just have an array of nextPoints (and/or previousPoints) which would allow for multiple way splitting.

Hope that helps in some vague way ;)

Posted 1 year ago #
gaminghorror
Member

Heh, this issue seems strikingly familiar to me. I'll be releasing a line-drawing game Starterkit on June 1st (Tuesday) on my website, see here for the announcement: http://www.learn-cocos2d.com/2010/05/linedrawing-game-starterkit-cocos2d-june-1st-2010/

I made the doxygen docs available that should give you some pointers about how i implemented "multiple moving objects with individual paths": http://www.learn-cocos2d.com/line-drawing-game-starterkit-docs

In general you want a Path class that holds a list of points. CGPoints stuffed in a NSMutableArray, no need to write your own linked list. Each moving sprite then has a member variable Path, so each sprite owns it's own path. You can then add (or remove) points for each sprite, and the sprite knows at which point it is at and what the next point is (if any) and then simply moves to that point.

Posted 1 year ago #

pagex
Member

Yeah that's kind of what I've had in mind, just let the sprite manage it's own path and movement.

I was able to create a class yesterday that simply reads the *path points array to give a visual representation of a sprites movement path using a draw()->ccDrawPoint combo.... speaking of which... why does 'draw' get called so fast?

-(void) draw {
    [super draw];
    [self drawPrimitives];
}

-(void) drawPrimitives{

	if([path_ length]){

		glPointSize(TILE_SIZE);

		/*** animate path on screen, idx is set in a tick method
		     to control the speed at which the draw method gets called.   ***/

		glColor4ub(0,0,0,200); // darker
		Position3D point = [path_ positionAtIndex:idx];
		CGPoint position = [self convertToPosition:point];
		ccDrawPoint(position);

		/*** display the entire path on screen  ***/

		glColor4ub(0,0,0,100); // lighter
		for (int i=0; i<[path_ length]; i++) {
			Position3D point = [path_ positionAtIndex:i];
			CGPoint position = [self convertToPosition:point];
			ccDrawPoint(position);
		}
	}
}

Note the reference to 'Position3D'... this is part of the A*pathfinding algorithm in ASIPathFinder that I modified to generate the paths... If you haven't heard of it here's the link...

http://allseeing-i.com/ASIPathFinder

Anyway, Looking forward to checking out the starter kit!!!

Thanks for all the suggestions! ...

Posted 1 year ago #

asinesio
Member

What I ended up with was a CCNode subclass that knew how to draw itself using ccDrawPoly, very similar to @pagex. Works great so far.

Posted 1 year ago #
TouchGameDev
Member

I am posting the original "line drawing game" start kit code for free in the next day or two. I will post the link. Same code @gaminghorror is trying to sell you. Except it's mine not his.

Posted 1 year ago #
shakti.pardeshi
Member

To,
TouchGameDev....

Hi,
I am able to draw the line using ccDrawLine method. I am collecting points on ccTouchesMoved method and add them to an NSMutable array. Then later in ccTouchesEnded, I am adding that NSMutable array to another NSMutable array. After that I add the CCNode as [self addChild:[DrawLine node]].
DrawLine the class inherited from a CCNode. Here I have written a -(void)draw method to draw line.

My problem is that when I draw the 2nd line, the 1st line gets deleted and 2nd line gets drawn.
I want all the lines which I am drawing should remain there till the time I delete them.
Can you please help me on this...

The code I have written is as follow.....
Please have a look at following code and please let me where I am making a mistake.
Is there any other way doing this?
Please help.
waiting for your reply..

-(void) ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *myTouch = [touches anyObject];

CGPoint location = [myTouch locationInView:[myTouch view]];

lastLocation = [ myTouch previousLocationInView: [myTouch view]];

CGPoint point = [[CCDirector sharedDirector] convertToGL:location];

newPoint = point;

NSString *coordPt = [NSString stringWithFormat:@"%@", NSStringFromCGPoint(point)];

[persistance_obj->cgPointArray addObject:coordPt];
}

-(void) ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
[self addChild:[drawLine node]];

NSMutableArray * tempArray = [[NSMutableArray alloc]init];
tempArray = [persistance_obj->cgPointArray copy];

[drawPath addObject:tempArray];
[tempArray release];

[persistance_obj->cgPointArray removeAllObjects];
}

-(void)draw
{

//persistance_obj = [persistance loaded];

drawFlag = 1;

glEnable(GL_LINE_SMOOTH);
glLineWidth(2.0f);
glColor4f(1.0f, 0.0f, 0.0f, 1.0f);

int x;

if(indexVal > 0)
{
x = indexVal - 1;
}
else
{
x = indexVal;
}

NSArray *array = [drawPath objectAtIndex:x];

for(int i = 0; i < [array count]; i++)
{
lastLocation1 = CGPointFromString([array objectAtIndex:i]) ;
if(i+1 < [array count])
{
endPoint1 = CGPointFromString([array objectAtIndex:i+1]);
}
else
{
endPoint1 = CGPointFromString([array objectAtIndex:i]);
}
ccDrawLine(lastLocation1, endPoint1);
}

}

Posted 1 year ago #
cocos2dbeginner
Member

@ TouchGameDev you wanted to post the link or ;) where is it?

Posted 1 year ago #

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