I am trying to create an ellipses. I used bodyWithEdgeLoopFromPath and it worked but there seems to be something wrong with it because sometimes other objects get caught in the middle of it.
But I want the ellipses to be solid, So I tried bodyWithPolygonFromPath (I want it static)
horizontalOval = [[SKShapeNode alloc] init];
theRect = CGRectMake(0, 0, self.frame.size.width/6 , 15);
CGMutablePathRef ovalPath = CGPathCreateMutable();
CGPathAddEllipseInRect(ovalPath, NULL, theRect);
horizontalOval.path = ovalPath;
horizontalOval.fillColor = [UIColor blueColor];
horizontalOval.physicsBody.dynamic = NO;
horizontalOval.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:ovalPath];
But got the error
SKPhysicsBody: Error attempting to create polygon with 17 vertices, maximum is 12
How do I create complex paths and make them solid?
Also when I pud it in position self.frame.size.width/2 and self.frame.size.height/2 It doesn't stay center, it goes a little to the right.
I had to theRect = CGRectMake(-40, 0........) to make it center but why is that?
UIBezierPath* ovalPath = [UIBezierPath bezierPathWithOvalInRect: _paddleRect];
But has 13 vertices. Trying to use PaintCode.
You can think of an edge body as one that has no volume, just the edges, a body with 'negative space' - that's why your objects got caught in the middle of it. As the Sprite Kit Programming Guide says:
The main difference between a edge and a volume is that an edge permits movement inside its own boundaries, while a volume is considered a solid object.
Since you want your oval to be a solid object, you do need a volume-based body. For these bodies, you have three options to create their shape: a circle (bodyWithCircleOfRadius:), a rectangle (bodyWithRectangleOfSize:), or a polygon (bodyWithPolygonFromPath:).
For an oval shape, you probably have to draw a polygon - however, the Sprite Kit physics engine will only accept those with a maximum of 12 vertices (that's why you were getting an error when drawing an actual ellipse). Your best bet is drawing a polygon using a helper tool, such as this one: http://dazchong.com/spritekit/ - just drag and drop your sprite and draw the path. Remember that the polygon must be convex (no angles over 180 degrees inside it) and that it can have a maximum of 12 vertices.
Also check out this answer for a similar issue: Ellipse SKPhysicsBody
Related
I have managed to draw a line with array of my random CGPoints.
-(void)drawLine
{
SKShapeNode *mainLine = [SKShapeNode node];
CGMutablePathRef pathToDraw = CGPathCreateMutable();
CGPathMoveToPoint(pathToDraw, NULL, 0, 0);
for(int i;i<pointsInMyView.count;i++)
{
CGPoint myPoint = [pointsInMyView[i] CGPointValue];
CGPathAddLineToPoint(pathToDraw, NULL, myPoint.x, myPoint.y);
mainLine.path = pathToDraw;
}
[mainLine setLineWidth:40];
[mainLine setStrokeColor:[SKColor whiteColor]];
mainLine.name = #"mainLine";
[self addChild:mainLine];
}
As you can see I am drawing a SKShapeNode. My goal is to check collision of my SKSpriteNode with my line. But of course, this shape node makes a frame that contains all points of my line, and in this case my ShapeNode is all over my view. My SpriteNode detects collision with this ShapeNode all the time.
I should draw multiple different ShapeNodes I guess, so every node would have its own frame. But if i do it this way, my line is not connected.
Is there some solution to draw this node by node and still get nice line.
Unfortunately nodes in SpriteKit cannot be concave (http://mathworld.wolfram.com/ConcavePolygon.html), with lines that cross over each other.
You will have to create separate nodes for each lines between adjacent points and then possibly join them together. you could do this either by:
Create the 1st segment and then add subsequent segments as children
of that 1st segment.
Create a non-visible node for the whole line and add wll the line
segments as children of that node.
Create physicsbodies for each segment and join them with
SKPhysicsJointFixed.
I'm developing a cocos2dX game. I use box2d for physics simulation. I'm trying to add a circular body and a rectangular body. Here is my code
// Create circular sprite and body
CCSprite* ball_sprite = CCSprite::create("ball.png");
this->addChild(ball_sprite);
b2BodyDef ballBodyDef;
ballBodyDef.type = b2_dynamicBody;
ballBodyDef.position.Set(screenSize.width/PTM_RATIO, screenSize.height/2/PTM_RATIO);//im running it in an iphone retina and screensize is 640x960
ballBodyDef.userData = ball_sprite;
ball_body = _world->CreateBody(&ballBodyDef);
b2CircleShape ballshape;
ballshape.m_radius = BALL_SIZE/2;
b2FixtureDef ballShapeDef;
ballShapeDef.shape = &ballshape;
ballShapeDef.density = 100.0f;
ballShapeDef.friction = 0.5f;
ballShapeDef.restitution = 0.7f;
ball_body->CreateFixture(&ballShapeDef);
// Create rectangular sprite and body
CCSprite* block_sprite = CCSprite::create("HelloWorld.png");
this->addChild(block_sprite);
b2BodyDef blockBodyDef;
blockBodyDef.type = b2_staticBody;
blockBodyDef.position.Set(0, screenSize.height/2/PTM_RATIO);
blockBodyDef.userData = block_sprite;
block_bodie = _world->CreateBody(&blockBodyDef);
b2PolygonShape blockshape;
blockshape.SetAsBox(B_WIDTH/PTM_RATIO,B_HEIGHT/PTM_RATIO);
b2FixtureDef blockShapeDef;
blockShapeDef.shape = &blockshape;
blockShapeDef.density = 100.0f;
blockShapeDef.friction = 0.5f;
blockShapeDef.restitution = 0.7f;
block_bodie->CreateFixture(&blockShapeDef);
The rectangular body is shown in the screen as expected.
But the circular body is not shown in the screen.
When I printed the position of circular body in the update function, the positions are large numbers around 2000. And this position is different each time I run the programm.
If the rectangular body is not added(commenting the line block_bodie->CreateFixture(&blockShapeDef);) then the circular body is shown in the screen as I expected.
What I'm doing wrong here?
Thanks in advance.
Are these two bodies overlapping when they are created? Most likely the circle is simply being pushed away by the rectangle, because the rectangle is static and the circle is dynamic. If you try creating both of them, but don't call the world Step function to run the physics simulation, you will probably see them both on screen.
You could create them so that they are not overlapping, or at least not overlapping as much, or make one of them a sensor, or set their collision category and mask bits so they don't interact.
Of course, I am assuming you are looking at the debug draw display, which is really the only way to know for sure what the physics engine is doing.
I have to create a CGPathRef to simulate the physic property in Sprite Kit.
I am trying to create an egg shape path by an half of circle plus half of oval.
the egg's ratio is 0.4(bottom of half circle) to 0.6 (upper of half oval);
However, I don't know why nothing is happen.
following code is the creation of the path:
self.egg = [SKSpriteNode spriteNodeWithImageNamed:IMAGE_NAME_EGG];
[self.egg setScale:0.2];
self.egg.position = CGPointMake(self.size.width/2,self.size.height - self.egg.size.height/2);
self.egg.name = IMAGE_NAME_EGG;
CGMutablePathRef path = CGPathCreateMutable();
CGPathAddArc(path, NULL, 0, self.egg.size.height*0.4, self.egg.size.width/2, M_PI, M_PI_2, NO);
CGPathAddEllipseInRect(path, NULL, self.egg.frame);
self.egg.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromPath:path];
self.egg.physicsBody.dynamic = YES;
self.egg.physicsBody.categoryBitMask = eggCategory;
self.egg.physicsBody.contactTestBitMask = floorCategory;
self.egg.physicsBody.collisionBitMask = floorCategory;
//self.eggCanMove = NO;
self.egg.physicsBody.allowsRotation = YES;
[self addChild:self.egg];
There is a better way to do this. Make a texture of your egg with p.e. Adobe Illustrator and use this method:
init(texture texture: SKTexture!,alphaThreshold alphaThreshold: CFloat,size size: CGSize) -> SKPhysicsBody
The SKTexture is your egg image. The body is defined by the colored pixels.
The alphaThresHold: The minimum alpha value for texels that should be part of the new physics body.
The Size is clear I think.
The texture is analyzed and all invisible pixels around the egg are ignored and only the color pixels are interpreted as the body of the SKPhysicsNode.
You shouldn't use too many of these because they are very expensive to calculate for the Physics Engine.
Variations of this method are found in the SpriteKit Class Reference.
I'm writing an application that will calculate a CGPoint and show a mark in an envelope (a diagram if you like). My envelope is just part of the background image in an UIImageView. What I want to do is to construct a sort of "line", corresponding to the envelopes limits (they're not straight lines, but curves) so that if the calculated CGPoint is to the left of this line, or to the right of another line, then the calculated point is not approved. Where it to be in the middle of these two, it's approved.
I was first thinking of drawing lines using CoreGraphics, but I'm not sure if one could check whether the calculated CGPoint is to the right or left of those lines.
The envelope is only 149px high, so I was also thinking of putting together a dictionary, where the keys where the y position and the values where the x position of the pixels that represented that defining boundary line.
The application is rather simple and is not animating anything. Does anybody have an idea of how to best come up with a solution for this sort of behavior?
You can do this by creating a CGPath that represents your boundary lines (the outline of your envelope) and testing that a point is contained in it with CGPathContainsPoint.
You'll have to do some trial and error to construct a CGPath that matches your envelope shape, try filling it in the drawRect method to see what your path actually is.
Here's an example with a circle path:
CGPoint viewCenter = CGPointMake(100,100);
CGPoint checkPoint = CGPointMake(110,110);
UIBezierPath *bpath = [UIBezierPath bezierPathWithArcCenter:viewCenter radius:50 startAngle:0 endAngle:DEGREES_TO_RADIANS(360) clockwise:YES];
CGPathRef path = [bpath CGPath];
BOOL inPath = CGPathContainsPoint(path, NULL, checkPoint, NO);
Here I have DEGREES_TO_RADIANS defined like this:
#define DEGREES_TO_RADIANS(angle) ((angle) / 180.0 * M_PI)
i have some uibezierpaths. as paths, they don't really have thickness.
but, I am hoping to find a way to define an area around a path like the grayish areas around the lines in this picture
basically, i want to test whether drawn lines fall within the buffer zone around the lines.
i thought this would be simple, but it's turning out to be much more complex than i thought. I can use the CGPathApply function to examine the points along my path, and then getting a range +or- each point, but it's more complicated than that with angles and curves. any ideas?
Expanding the width of a path is actually quite difficult. However, you could just stroke it with a thicker width and get pretty much the same effect. Something like...
CGContextSetRGBStrokeColor(context, 0.4, 0.4, 0.4, 1.0);
[path setLineWidth:15];
[path stroke];
CGContextSetRGBStrokeColor(context, 0.0, 0.0, 0.0, 1.0);
[path setLineWidth:3];
[path stroke];
...would produce a picture like the one in your question. But I doubt that's news to you.
The real trick is the test of "whether drawn lines fall within the buffer zone." That problem is very similar to one which I just answered for myself in another question. Take a look at the LineSample.zip code I shared there. This implements a bitmap/bitwise data comparison to detect hits on lines much like you need. You could just draw the thicker "buffer" paths into the bitmap for testing and show the thinner lines in your view.
Basically, you want to check if any point falls inside a region of specified size around your path.
It is actually very simple to do. First, you need a value which will define the amount of space around path you want to test. Let's say 20 points. So what you need to do is start a FOR loop, starting from -20 to 20, and at each iteration, create a copy of your path, translate the path's x and y co-odrinates, check each of them.
All of this is more clear in this code sample.
CGPoint touchPoint = /*get the point*/;
NSInteger space = 20;
for (NSInteger i = -space; i < space; i++) {
UIBezierPath *pathX = [UIBezierPath bezierPathWithCGPath:originalPath.CGPath];
[pathX applyTransform:CGAffineTransformMakeTranslation(i, 0)];
if ([pathX containsPoint:touchPoint]) {
/*YEAH!*/
}
else {
UIBezierPath *pathY = [UIBezierPath bezierPathWithCGPath:originalPath.CGPath];
[pathY applyTransform:CGAffineTransformMakeTranslation(0, i)];
if ([pathY containsPoint:touchPoint]) {
/*YEAH!*/
}
}
}