1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
// This class is a game object controller of sorts.
// It basically ties the physics and graphics objects together, and gives you a
// place to put your controlling logic.
#import "FallingButton.h"
#define SIZE 100.0f
@implementation FallingButton
@synthesize button;
@synthesize touchedShapes;
// This property fulfills the ChipmunkObject protocol.
// It is perhaps the most important thing this class does.
// By maintaining this list of objects, a ChipmunkSpace can easily add and remove complicated game objects.
// Using the C API, you would have to keep references to each Chipmunk object and add them one by one
// based on their type to the Chipmunk space.
@synthesize chipmunkObjects;
static cpFloat frand_unit(){return 2.0f*((cpFloat)rand()/(cpFloat)RAND_MAX) - 1.0f;}
- (void)buttonClicked {
// Apply a random velcity change to the body when the button is clicked.
cpVect v = cpvmult(cpv(frand_unit(), frand_unit()), 300.0f);
body.vel = cpvadd(body.vel, v);
body.angVel += 5.0f*frand_unit();
}
- (void)updatePosition {
// ChipmunkBodies have a handy affineTransform property that makes working with Cocoa or Cocos2D a snap.
// This is all you have to do to move a button along with the physics!
button.transform = body.affineTransform;
// Alternatively, you could build a transform yourself from the body's position and rotation:
// cpVect pos = body.pos;
// button.transform = CGAffineTransformRotate(CGAffineTransformMakeTranslation(pos.x, pos.y), body.angle);
}
- (id)init {
if(self = [super init]){
// Set up the UIButton.
button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setTitle:@"Click Me!" forState:UIControlStateNormal];
[button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
[button setBackgroundImage:[UIImage imageNamed:@"logo.png"] forState:UIControlStateNormal];
button.bounds = CGRectMake(0, 0, SIZE, SIZE);
[button addTarget:self action:@selector(buttonClicked) forControlEvents:UIControlEventTouchDown];
// Set up Chipmunk objects.
cpFloat mass = 1.0f;
// The moment of inertia is like the rotational mass of an object.
// Chipmunk provides a number of helper functions to help you estimate the moment of inertia.
cpFloat moment = cpMomentForBox(mass, SIZE, SIZE);
// A rigid body is the basic skeleton you attach joints and collision shapes too.
// Rigid bodies hold the physical properties of an object such as the postion, rotation, and mass of an object.
// You attach collision shapes to rigid bodies to define their shape and allow them to collide with other objects,
// and you can attach joints between rigid bodies to connect them together.
body = [[ChipmunkBody alloc] initWithMass:mass andMoment:moment];
body.pos = cpv(200.0f, 200.0f);
// Chipmunk supports a number of collision shape types. See the documentation for more information.
// Because we are storing this into a local variable instead of an instance variable, we can use the autorelease constructor.
// We'll let the chipmunkObjects NSSet hold onto the reference for us.
ChipmunkShape *shape = [ChipmunkPolyShape boxWithBody:body width:SIZE height:SIZE];
// The elasticity of a shape controls how bouncy it is.
shape.elasticity = 0.3f;
// The friction propertry should be self explanatory. Friction values go from 0 and up- they can be higher than 1f.
shape.friction = 0.3f;
// Set the collision type to a unique value (the class object works well)
// This type is used as a key later when setting up callbacks.
shape.collisionType = [FallingButton class];
// Set data to point back to this object.
// That way you can get a reference to this object from the shape when you are in a callback.
shape.data = self;
// Keep in mind that you can attach multiple collision shapes to each rigid body, and that each shape can have
// unique properties. You can make the player's head have a different collision type for instance. This is useful
// for brain damage.
// Now we just need to initialize the instance variable for the chipmunkObjects property.
// ChipmunkObjectFlatten() is an easy way to build this set. You can pass any object to it that
// implements the ChipmunkObject protocol and not just primitive types like bodies and shapes.
// Notice that we didn't even have to keep a reference to 'shape'. It was created using the autorelease convenience function.
// This means that the chipmunkObjects NSSet will manage the memory for us. No need to worry about forgetting to call
// release later when you're using Objective-Chipmunk!
// Note the nil terminator at the end! (this is how it knows you are done listing objects)
chipmunkObjects = [ChipmunkObjectFlatten(body, shape, nil) retain];
}
return self;
}
- (void) dealloc
{
[button release];
[body release];
[chipmunkObjects release];
[super dealloc];
}
@end
|
