I'm trying to make the box2d accelerometer work, I have a car sprite and want it to move left and right, when the iPhone is tilted.
Here is the code for the sprite:
- (void)spawnCar {
car = [CCSprite spriteWithSpriteFrameName:#"car.jpg"];
car.position = ccp(160, 250);
car.tag = 2;
[self addBoxBodyForSprite:car];
[_spriteSheet addChild:car];
}
How can implement the accelerometer to work for left and right?
Just do this...
in your init add
self.isAccelerometerEnabled = YES;
and then add this method...
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {
b2Vec2 gravity(-acceleration.y * 15, acceleration.x *15);
world->SetGravity(gravity);
}
Related
I want to detect the device motion like Panorama i.e. motion from my left side to Right side.
I tried with the accelerometer but i can't able to do it.
I like to move one image in a straight line as the device move.
My code is as follow:
- (void)viewDidLoad
{
[super viewDidLoad];
[[UIAccelerometer sharedAccelerometer] setUpdateInterval:1/60];
[[UIAccelerometer sharedAccelerometer]setDelegate:self];
}
pragma mark - Accelerometer Delegate
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:
(UIAcceleration *)acceleration{
valueX = acceleration.x*100.0;
valueY = acceleration.y*30.0;
float newX = (float)(ball.center.x + valueX);
CGPoint newCenter = CGPointMake(newX, 50);
ball.center = newCenter;
}
How can I do this? Because there are many apps who uses this.
Please guide me.
Thanks..
I made a space game where you use the accelerometer to move a spaceship, When I try the game on my devices (iPad, iPhone) it work well with no errors or incorrect behavior.
I upload my game to the App Store and it was approved, but when I downloaded the game from the App Store, the accelerometer wasn't working and my spaceship was stuck in one direction.
I tried many devices and they all have same problem.
Note: I used the cocos2d and box2d frameworks.
If anybody have any idea, please help!
Use UIAccelerometerDelegate
UIAccelerometer *accelerometer;
In .m file
# pragma mark To Enable Acceleromete
self.isAccelerometerEnabled = YES;
self.accelerometer = [UIAccelerometer sharedAccelerometer];
self.accelerometer.updateInterval = 0.025;
self.accelerometer.delegate = self;
Use these delegates methods
#pragma Mark Accelerometer
-(void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration
{
// Set up variables
CGSize winSize = [CCDirector sharedDirector].winSize;
#define kFilteringFactor 0.5
#define kShipMaxPointsPerSec (winSize.height*0.5)
#define kRestAccelX (xCallib)
#define kMaxDiff 0.2
#define kRestAccelY (yCallib)
#define kMaxDiffY 0.1
UIAccelerationValue rollingX=0;
float accelX;
// High pass filter for reducing jitter
rollingX = (acceleration.x * kFilteringFactor) + (rollingX * (1.0 - kFilteringFactor));
accelX = acceleration.x - rollingX;
// Calculate movement for x and y axis
float accelDiffX = accelX - kRestAccelX;///
float accelFractionX = accelDiffX / kMaxDiff;//
movementX = kShipMaxPointsPerSec * accelFractionX;
// Thresh holds for x and y axis movement
willMoveX = YES;
if (((movementX < 45.0f) && (movementX > -45.0f)))
willMoveX = NO;
}
#pragma Mark Accelerometer Update Methods
-(void) update:(ccTime)dt
{
CCSprite *player =(CCSprite *) [self getChildByTag:objPlayerShipTag];
CGSize screenSize = [[CCDirector sharedDirector]winSize];
float oldX = [player position].x;
float newX;
if (willMoveX) {
newX = [player position].x + (movementX * dt);
} else newX = oldX;
if ((newX > (screenSize.width -45)) || newX < 45.0f ) {
newX = oldX;
}
[player setPosition:ccp(newX,90)];
// ++++++++ To generate Bullet and Bomb Power +++++++
[self checkForCollisionWithPowersBullets]; //NEW
[self checkForCollisionWithPowersBomb];
}
Hi everyone I'm french so scue me for my english. So I have a problem.What I'm doing is when I turn device to left or right with accelerometer an image rotate in the opposite direction of the rotation of the device it create a cool effect but when I rotate the device with accelerometer the image is rotating but it is always trembling, vibrating the movement is not smooth. What can I do ? here is the code:
#import "QuartzCore/QuartzCore.h"
#define CONST_fps 100.
#define CONST_map_shift 0.05
#implementation MapViewRotationViewController
- (void)viewDidLoad {
[super viewDidLoad];
// accelerometer settings
[[UIAccelerometer sharedAccelerometer] setDelegate:self];
[[UIAccelerometer sharedAccelerometer] setUpdateInterval:(1.0 / CONST_fps)];
}
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration
{
static CGFloat ZZ = 0.;
CGFloat z = (atan2(acceleration.x, acceleration.y) + M_PI);
if (fabsf(ZZ - z) > CONST_map_shift)
{
viewToRotate.layer.transform = CATransform3DMakeRotation(ZZ=z, 0., 0., 10.);
}
}
#end
You need to do a trick that is called high pass filter. It filters trembling, only significant changes will pass.
You can google it, or search on StackOverflow. For example, here: How do you implement a Highpass filter for the IPhone accelerometer?
i use following code to move my Box2D object into screen, but because gravity of my world or something else i dont know why my objects is forced to move down, i am new to box2d.
i want to move my object in entire world without gravity.
-(void) tick:(NSTimer *)timer {
int32 velocityIterations = 8;
int32 positionIterations = 1;
world->Step(1.0f/60.0f, velocityIterations, positionIterations);
for (b2Body* b = world->GetBodyList(); b; b = b->GetNext())
{
if (b->GetUserData() != NULL)
{
UIView *oneView = (UIView *)b->GetUserData();
CGPoint newCenter = CGPointMake(b->GetPosition().x * PTM_RATIO,self.view.bounds.size.height - b->GetPosition().y * PTM_RATIO);
oneView.center = newCenter;
CGAffineTransform transform = CGAffineTransformMakeRotation(- b->GetAngle());
oneView.transform = transform;
}
}
}
my accelerometer code is as follow.
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {
b2Vec2 gravity;
gravity.Set( acceleration.x * 1.81, acceleration.y * 1.81 );
world->SetGravity(gravity);
}
pleas if any one work around.
Thanks.
As i understand you want to move your object setting it's position. It's a bad idea because it will provide non-physical behavior of the bodies colliding with your object. That's because if you will only change the position of your body it's velocity for physics engine will be still zero and collision will be processed according to zero speed of your object.
A better solution is to use b2_kinematicBody type for your object. Then you will be able to control it's motion specifying it's velocity vector and physics will behave as expected. Also the gravity (and no other forces) will not be applied to your object because of it's type.
EDIT
//creation
b2BodyDef bDef;
bDef.type = b2_kinematicBody;
bDef.position.Set(5, 6);
b2Body *body = physWorld->CreateBody(&bDef);
//control
body->SetLinearVelocity(b2Vec2(3, 4));
I haven't had any experience with the accelerometer yet and i was wondering how i would move my UIImageView with the accelerometer, can anyone point me to any tutorials or give me a little help?
thanks,
harry
There are a collection of tutorials here http://www.iphonedevforums.com/forum/sdk-coding-help/854-how-use-accelerometer.html which should meet your needs.
//viewDidLoad
UIAccelerometer *accel = [UIAccelerometer sharedAccelerometer];
accel.delegate = self;
accel.updateInterval = 1.0f/60.0f;
//then
- (void)accelerometer:(UIAccelerometer *)acel didAccelerate:(UIAcceleration *)aceler {
//move your image here
//based on aceler.x aceler.y aceler.z
}