I'm sure this is somewhere already on the internet, but I can't seem to find it. Say I want to add some balloons that float upwards in a scene (where gravity is downwards for everything else). What's the best way to go about it?
So far, I have set the balloon's mass to almost nothing, and applied an upwards force to it. It seems to work okay, but I'm hoping there is a more appropriate way of doing it.
Thank you
Related
So I have my game, made with SpriteKit and Obj-C. I want to know a couple things.
1) What is the best way to make scroll-views in SpriteKit?
2) How do I get this special kind of scroll-view to work?
The kind of scroll-view I'd like to use is one that, without prior knowledge, seems like it could be pretty complicated. You're scrolling through the objects in it, and when they get close to the center of the screen, they get larger. When they're being scrolled away from the center of the screen, they get smaller and smaller until, when their limit is met, they stop minimizing. That limitation goes for getting bigger when getting closer to the center of the screen, too.
Also, I should probably note that I have tried a few different solutions for cheap remakes of scroll views, like merely adding the objects to a SKNode and moving the SKNode's position relative to the finger's, and its movement . . . but that is not what I want. Now, if there is no real way to add a scroll-view to my game, this is what I'm asking. Will I simply have to do some sort of formula? Make the images bigger when they get closer to a certain spot, and maybe run that formula each time -touchesMoved is called? If so, what sort of formula would that be? Some complicated Math equation subtracting the node's position from the center of the screen, and sizing it accordingly? Something like that? If that's the case, will you please give me some smart Math formula to do that, and give it to me in code (possibly a full-out function) format?
If ALL else fails, and there is no good way to do this, what would some other way be?
It is possible to use UIScrollViews with your SpriteKit scenes, but there's a bit of a workaround involved there. My recommendation is to take a look at this github project, that is what I based my UIScrollView off of in my own projects. From the looks of it, most of the stuff you'd want has actually been converted to Swift now, rather than Objective-C when I first looked at the project, so I don't know how that'll fare with you.
The project linked above would result in your SKScene being larger than the screen (I assume that is why it would need to be scrolled), so determining what is and is not close to the center of the scene won't be difficult. One thing you can do is use the update loop in SpriteKit to constantly update the size of Sprites (Perhaps just those on-screen) based on their distance from a fixed, known center point. For instance, if you have a screen of width and height 10, then the midpoint would be x,y = 5,5. You could then say that size = 1.0 - (2 * distance_from_midpoint). Given you are at the midpoint, the size will be 1.0 (1.0 - (2 * 0)), the farther away you get, the smaller your scale will be. This is a crude example that does not account for a max or min fixed size, and so you will need to work with it.
Good luck with your project.
Edit:
Alright, I'll go a bit out of my way here and help you out with the equation, although mine still isn't perfect.
Now, this doesn't really give you a minimum scale, but it will give you a maximum one (Basically at the midpoint). This equation here does have some flaws though. For one, you might use this to find the x and y scale of your objects based on their distance from a midpoint. However, you don't really want two different components to your scale. What if your Sprite is right next to the x midpoint, and the x_scale spits out 0.95? Well, that's almost full-sized. But if it is far away from the midpoint on the y axis, and it gives you a y scale of, say 0.20, then you have a problem.
To solve that, I just take the magnitude or hypotenuse of the vector between the current coordinate and the coordinate of the current sprite. That hypotenuse gives me an number that represents the true distance, which eliminates the problem with clashing scale values.
I've made an example of how to calculate this inside Google's Go-Playground, so you can run the code and see what different scales you get based on what coordinate you plug in. Also, the equation used in there is slightly modified, It's basically the same thing as above but without the maxscale - part of the front part of the equation.
Hope this helps out!
Embedding Attempt:
see this code in play.golang.org
basically I am trying to edit not only the appearance of the button(thats the easy part) but the frame that detects the touch to be a rhombus rather then a square
html example:http://irwinproject.com
I've tried CGAfflineTransform however it doesn't allow me to make non rectangular objects. is there a way to skew
Im just wondering if this is possible because, if not could someone point me in a direction the only viable answer I've found is resorting to something along the lines of a spriteKit;
I found this however this implementation leaves dead spots on buttons where they overlap
custom UIButton with skewed area in iPhone
is there a way to message people on here there was a gentleman who said he figured out how to transform but never posted his solution.
In order to modify the touch area of an oddly shaped button you could use a solution similar to OBShapedButton. I have used this particular project in the past myself for adjacent hexagon buttons and it worked perfectly. That said, you may have to modify it a bit to work with drawn shapes instead of images.
I'm taking my first steps through Unity, as a follow up to this question:
http://answers.unity3d.com/questions/56697/isometric-game-camera-limits
I now realized that I don't know how to make a collider actually collide. Now I have a GameObject I move around instead of the camera, and the camera is a child to that object. It has a box collider, and there're four other box colliders around the level so it will collide against them.. and it's not working, of course, because I was changing the position variable by hand. What do I do so this collides? use a rigidBody and apply forces to it? is there a way to put a maxVelocity on it? I can't see one, besides a rigidbody seems sort of overkill for what I'm trying to do. Otherwise I guess I just put mass 1, and export drag and force, but I'd much rather work with a maxSpeed, because drag will also affect the acceleration rate
I don't know if you have missed any steps but I can tell you what I've done if it helps any. Create a game object. Click on the object in the hierarchy and go to the top menu and component->physics->box collider.After you add the box collider you may have to adjust the size of the colliders as well. In addition make sure you character you are walking around with also has a collider.
You can take a programmatic approach. Do I get you right that you want to drag the cam around with the mouse or move it with keys? You can check the camera position by hand and apply boundings that way. It is quite easy to implement if your camera is locked into a single box.
I get the concept of the NSIntersectionRect for collision detection but I can't seem to think of how to implement it for my project. It's nothing fancy, click a button and a view subclass is called and places a circle in the window at a random location. Click within the that view and the circle pulses (this makes it the active view). If you have an active view, clicking anywhere outside it (but not on another circle) will move that view to the click point.
I'm using [activeView animator setFrame: NSMakeRect(x, y, w, h)] to move the active view. Can I use this for collision detection or do I have to go with CABasicAnimation? Basically what I am looking to do is detect collisions with other circles (no physics needed at this point, just stop the movement) and/or with the bounds of the app window.
If someone could nudge me in the right direction (tutorial link, code snippet) I'd appreciate it.
Edit: Based on the well detailed answer below I need to be a bit more clear. I'm confused on where to implement the collision detection. The animator method of a view class is one line of code. How would I iterate through every static circle on the screen to run a collision check? Which is why I am wondering first, if I need to go with CoreAnimation, OpenGL or something like Chipmunk and then if I could get a nudge or assist that would be great.
Later .. in answer to your recent questions:
Which is why I am wondering first, if I need to go with CoreAnimation, OpenGL or something like Chipmunk and then if I could get a nudge or assist that would be great.
Answer - you absolutely definitely do not need OpenGL :) Next, you definitely do not need a physics library like Box2D or Chipmunk ... you could go that way if you wanted to, but, it would be a huge amount of unnecessary work. To be clear: until you are totally familiar with using DrawRect, things like Chipmunk are useless for you anyway, so just forget that.
Core Animation will not really help you. To be clear, you possibly want to interrupt an animation as it is happening. Is that correct?
I'm confused on where to implement the collision detection. The animator method of a view class is one line of code. How would I iterate through every static circle on the screen to run a collision check?
Bad news... if you actually want to interrupt the animation, if there is a collision, forget about Core Animation. Core Animation will let you send it from A to B as "one unit" of animation. It will NOT let you stop it in the middle (in case of a collision). So, that's that.
To be clear, that is what you want to do right? You set the circle in motion, and IF it hits something along the way, you want it to stop. Is this correct? if so, completely forget about Core Animation and throw away any work you've done so far.
You are going to have to dive in to "real" programming (whatever that means) and start using drawRect. Are you up for it?!
At this point I might just mention: consider buying a copy of Corona (it's like $100 -- I'm sure the demo is free). You can do everything you are describing in, literally, five minutes using Corona. (1/10th the time taken to write this post??) I always recommend this to people who are iPhone Curious. If you don't really want to spend 6 to 18 months becoming a gun iPhone programmer - just click to Corona for iPhone and in a fraction of the time it's taken you to use Stack Overflow, you can have your circles bouncing wildly on the iPhone screen.
So, failing that, you're gonna have to get to work and learn how to launch a timer (NSTimer) and use drawRect in a UIView.
Craate a new class called MyFirstView (.h and .m file) that is a subclass of UIView (not UIViewController, which is for wimps!). You'll need a drawRect method in MyFirstView and proceed from there!
Original answer..
I'm not sure I understand what you are saying, but to be clear:
You want to detect a collision between two circles. In your case, all the circles are the same diameter. Is that correct?
If so, fortunately it is very easy to do.
Write a routine that gets the distance between two CGPoints. (If you don't know how to do that I included it below.)
Next step, you must know the DIAMETER of your circles. Let's say it is 50.0 for the example.
Next, here is a routine that checks if two circles are colliding:
static inline bool areTwoCirclesColliding( CGPoint aa, CGPoint bb )
{
return ( distanceBetweenTwoCGPoints(aa,bb) < 50.0 );
}
(Note... if you are new to Objective C, note that the above is totally valid code. Simply paste it in at the top of your file. OK?)
Finally, you just have to check all your circles, one against the other, to see if any are colliding.
If you have a simple fixed number of circles, let's say three or so, just write out all the lines of code to check if any of the combinations are colliding, hence:
areTwoCirclesColliding(a,b)
areTwoCirclesColliding(a,c)
areTwoCirclesColliding(b,c)
If you have an array or some sort of list of circles, you just have to go through them all and check that each one is not touching any other. In pseudocode it might be something like this...
for n in 1 to numberCircles
oneCircle = circles[n]
for m in n+1 to numberCircles
anotherCircle = circles[m]
if ( areTwoCirclesColliding(oneCircle,anotherCircle) )
.. break, you found a collision
Alternately you could write it like this, makes no difference..
for each aa in circles
for each bb in circles
if (aa != bb) if (areTwoCirclesColliding(aa,bb)) .. break, found collision
{Aside - For the record it is utterly unimportant that you check each pair twice in that pseudocode, no problem.}
It is impossible for me to write the actual code for you as i have no idea what structure you are using, sorry.
Of course if your circle is an object, you could sensibly make it test itself against all the other circles, same idea. If you have an SQL database of circles, test them all against each other.
So fortunately you can see it is one (1) line of code to check if two circles are colliding. And it's about 3 or 4 lines of code to check all your circles for collisions. So fortunately about 5 lines in total!
So, that is an incredibly simple tutorial on video game physics, part 1.1.1.1 !!!! Hope it helps! If that is not what you were trying to achieve, it was a complete waste of typing! :)
For the record here's a routine to get the distance between two CGPoints:
static inline float rawDistance(float x, float y, float p, float q)
{
return sqrt( ((x-p)*(x-p)) + ((y-q)*(y-q)) );
}
static inline float distanceBetweenTwoCGPoints( CGPoint a, CGPoint b )
{
return rawDistance( a.x, a.y, b.x, b.y );
}
(Note... if you are new to Objective C, note that the above is totally valid code. Simply paste it in at the top of your file. OK? It's exactly like using any everyday function supplied by Apple such as x=CGLayerGetContext(), for example. Enjoy!)
Later .. and by popular demand, for an object, Circle...
-(bool)isTouchingOtherCircle:(circle)c
{
return areTwoCirclesColliding(self.center, c.center);
}
-(bool)isTouchingAnyOtherCircle
{
for oc in yourCircles
if (oc != self)
if ( [self isTouchingOtherCircle:oc] )
return false;
return true;
}
I used to use and love RBSplitView, however I failed at reimplementing it programmatically as a certain version of xcode does not support IB plugins anymore.
Therefore I went back to using NSSplitView. NSSplitView is fine for what I need, the thing is that the autoSave of NSSplitView is broken. So I decided to implement it myself.
The thing I am doing at the moment is resizing 1 of the subviews of the NSSplitView.
What is the proper way of resizing an NSSplitView? - setPositionOfDivider:itIndex: should be the way to go ( haven't tried it ), however I do not know how to get the current position of the divider.
-- thanks in advance
In my experience, NSSplitView hates you and wishes you harm. RBSplitView is so much better, it is worth IMO the headache of programatic layout (and I've been so burned with the ShortcutRecorder IB plugins that I will never go back to IB plugins).
That said....
The only way that I know of to determine the current position of the divider is to look at the subviews, find the divider's view, take it's frame, and work out its position keeping in mind the dividerThickness. It is insane that you have to write that code, but the code isn't that incredibly difficult, and you can put it in a category.
Or go back to RBSplitView while you still can, if your needs are ever going to be complicated.
I'm using Swift here but the same method should exist in Objective C:
mySplitter.setPosition(123, ofDividerAtIndex: 0)