I move a simple CCSprite around the screen of an iOS device using this code:
[self schedule:#selector(update:) interval:0.0167];
- (void) update:(ccTime) delta {
CGPoint currPos = self.position;
currPos.x += xVelocity;
currPos.y += yVelocity;
self.position = currPos;
}
This works however the animation is not smooth. How can I improve the smoothness of my animation?
My scene is exceedingly simple (just has one full-screen CCSprite with a background image and a relatively small CCSprite that moves slowly).
I've logged the ccTime delta and it's not consistent (it's almost always greater than my specified interval of 0.0167... sometimes up to a factor of 4x).
I've considered tailoring the motion in the update method to the delta time (larger delta => larger movement etc). However given the simplicity of my scene it's seems there's a better way (and something basic that I'm probably missing).
The scheduler will try to accommodate and call your selector as per your interval but if there are other processes running, it can be earlier or later (hence why the inconsistency).
Instead, multiply your xVelocity and yVelocity by delta - this should scale the velocities into a far smoother motion.
For example:
- (void) update:(ccTime) delta {
CGPoint currPos = self.position;
currPos.x += (xVelocity * delta);
currPos.y += (yVelocity * delta);
self.position = currPos;
}
Try using the default [self scheduleUpdate] method rather than calling it directly as you are doing, see if that makes a difference. This method is designed for what you are doing and may be smoother.
Related
I'm developing a mobile game in Unity3d which the player needs to move a stick that is placed just a little bit higher then the finger with transform.position and block a ball that is moved with Force.Mode2D.impulse. The problem is that the ball goes through the stick if the stick is moved too fast. Could anyone please teach me how to code the stick movement with Force (or any other way that works) that still moves according to the finger position on touch screen ( A.K.A Input.mousePosition) instead of using buttons?
The code goes as such if anyone needs the info;
Stick:
float defencePosX = Mathf.Clamp( Input.mousePosition.x / Screen.width * 5.6f - 2.8f , -2.8f, 2.8f);
float defencePosY = Mathf.Clamp( Input.mousePosition.y / Screen.height * 10 - 4f, -3.3f, -0.5f);
this.transform.position = new Vector3 (defencePosX, defencePosY, 0);
Ball:
projectileSpeed = Random.Range (maxSpeed, minSpeed);
projectileSwing = Random.Range (-0.001f, 0.001f);
rb.AddForce (new Vector2 (projectileSwing * 1000, 0), ForceMode2D.Impulse);
rb.AddForce (new Vector2 (0, projectileSpeed), ForceMode2D.Impulse);
a video of the bug:
https://youtu.be/cr2LVBlP2O0
basicly if i dont move the stick it hits but if i move it fast the ball goes right through. (the bouncing sound effect doesnt work if itss too fast as well)
When working with physics objects, you'll want to use just the Rigidbody component when moving them. Otherwise, it's interpreted as a teleport and no physics is applied and no movement is calculated.
Try using Rigidbody.MovePosition instead of transform.position.
Also, make sure the Rigidbody components on your stick AND ball both have collisionDetectionMode set to 'Continuous Dynamic'. That's how you get small fast-moving physics objects to hit one another in between frames.
float defencePosX = Mathf.Clamp( Input.mousePosition.x / Screen.width * 5.6f - 2.8f , -2.8f, 2.8f);
float defencePosY = Mathf.Clamp( Input.mousePosition.y / Screen.height * 10 - 4f, -3.3f, -0.5f);
rb.MovePosition(new Vector3 (defencePosX, defencePosY, 0));
Id recommend that you set the balls force to Vector3.zero before adding force to it, or that you use the collider of your blocking movement as a bounce pad for the ball.
Please remember to check that your colliders are scaled correctly according to the blocker.
A video displaying your issue would be helpful to understand it better.
What is the standard method for smooth camera movement within SceneKit (OpenGL)?
Manually changing x,y isn't smooth enough, yet using CoreAnimation creates "pulsing" movement. The docs on SceneKit seem to be very limited so any examples would be appreciated, I'm currently doing this:
- (void)keyDown:(NSEvent *)theEvent {
int key = [theEvent keyCode];
int x = cameraNode.position.x;
int y = cameraNode.position.y;
int z = cameraNode.position.z;
int speed = 4;
if (key==123) {//left
x-=speed;
} else if (key==124) {//right
x+=speed;
} else if (key==125) {//down
y-=speed;
} else if (key==126) {//up
y+=speed;
}
//move the camera
[SCNTransaction begin];
[SCNTransaction setAnimationDuration: 1.0];
// Change properties
cameraNode.position = SCNVector3Make(x, y, z);
[SCNTransaction commit];
}
To minimise the pulsing movements (due to the key repeat) you can use an "easeOut" timingFunction:
//move the camera
[SCNTransaction begin];
[SCNTransaction setAnimationDuration: 1.0];
[SCNTransaction setAnimationTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut]];
// Change properties
cameraNode.position = SCNVector3Make(x, y, z);
[SCNTransaction commit];
That said, the best thing to do here is probably to manage a target position (a vector3) yourself and update the position of the camera at every frame to go to this target smoothly.
I've been experimenting with this. The best I've found so far is to record the state of the input keys in internal state, modified by keyDown: and keyUp:, and run an NSTimer to apply them. The timer uses the actual, measured time delta between firings to determine how far to move the camera. That way irregular timings don't have too much effect (and I can call my method to update the camera position at any time without worrying about changing its movement speed).
It takes some work to make this behave correctly, though. keyDown: and keyUp: have some obnoxious behaviours when it comes to game input. For example, repeating keys. Also, they may fire even after your view loses focus or your app goes to the background, if keys are held down across the transition. Etc. Not insurmountable, but annoying.
What I haven't yet done is add acceleration and deceleration, which I think will aid the perception of it being smooth. Otherwise it feels pretty good.
I move camera using this code:
let lerpX = (heroNode.position.x - followCamera.position.x) * 0.05
let lerpZ = (heroNode.position.z - followCamera.position.z) * 0.05
followCamera.position.x += lerpX
followCamera.position.z += lerpZ
I want to have a random sprite spawn and move across the screen.
I'm using CGRectIntersectsRect to detect collisions between the player and the randomly spawned sprites.
I've done this, the code works fine - when I have a set interval.
However, when I add randomness to the sprite's spawn times, collisions do not work all the time. Most collisions do not work at all.
I'm not sure what I'm doing wrong and would really appreciate any help in the right direction.
I think it has something to do with the schedule interval and how long it actually takes for the sprite to move across the screen.
Not sure though.
Also, if you could, I would also like to know the best way to remove enemySprite from the scene after it is off the screen?
Here's my code:
-(void)targetTimer {
[self schedule: #selector(enemySprite:) interval: 3.0f];
}
-(void)enemySprite:(id)sender {
CGSize winSize = [[CCDirector sharedDirector] winSize];
//SPAWN ENEYMY
enemySprite = [CCSprite spriteWithFile:#"eneymySprite.png"];
enemySprite.position = ccp (winSize.width/16, winSize.height/5);
[self addChild:enemySprite z:300];
CCAction *moveEnemyRight = [CCMoveTo actionWithDuration:3 position:ccp (winSize.width/1, winSize.height/5) ];
[enemySprite moveEnemyRight];
if ( enemySprite.position.y >= winSize.width ) {
//Best Way to Remove enemySprite from Scene?
}
NSLog(#"Collision");
[self unschedule:#selector(enemySprite:)];
unsigned int t = arc4random()%4 + 1;
[self schedule:#selector(enemySprite:) interval: t];
}
You have to craete an array of your enemies to be able to check if they leave game area (screen in your case). In your code this part
if ( enemySprite.position.y >= winSize.width ) {
//Best Way to Remove enemySprite from Scene?
}
will never be called. Because enemySprite.position.y >= winSize.width will be always NO as you just created this sprite and place it to the game area with coordinate
ccp(winSize.width/16, winSize.height/5)
I've been doing some programming for iPhone lately and now I'm venturing into the iPad domain. The concept I want to realise relies on a navigation that is similar to time machine in osx. In short I have a number of views that can be panned and zoomed, as any normal view. However, the views are stacked upon each other using a third dimension (in this case depth). the user will the navigate to any view by, in this case, picking a letter, whereupon the app will fly through the views until it reaches the view of the selected letter.
My question is: can somebody give the complete final code for how to do this? Just kidding. :) What I need is a push in the right direction, since I'm unsure how to even start doing this, and whether it is at all possible using the frameworks available. Any tips are appreciated
Thanks!
Core Animation—or more specifically, the UIView animation model that's built on Core Animation—is your friend. You can make a Time Machine-like interface with your views by positioning them in a vertical line within their parent view (using their center properties), having the ones farther up that line be scaled slightly smaller than the ones below (“in front of”) them (using their transform properties, with the CGAffineTransformMakeScale function), and setting their layers’ z-index (get the layer using the view’s layer property, then set its zPosition) so that the ones farther up the line appear behind the others. Here's some sample code.
// animate an array of views into a stack at an offset position (0 has the first view in the stack at the front; higher values move "into" the stack)
// took the shortcut here of not setting the views' layers' z-indices; this will work if the backmost views are added first, but otherwise you'll need to set the zPosition values before doing this
int offset = 0;
[UIView animateWithDuration:0.3 animations:^{
CGFloat maxScale = 0.8; // frontmost visible view will be at 80% scale
CGFloat minScale = 0.2; // farthest-back view will be at 40% scale
CGFloat centerX = 160; // horizontal center
CGFloat frontCenterY = 280; // vertical center of frontmost visible view
CGFloat backCenterY = 80; // vertical center of farthest-back view
for(int i = 0; i < [viewStack count]; i++)
{
float distance = (float)(i - offset) / [viewStack count];
UIView *v = [viewStack objectAtIndex:i];
v.transform = CGAffineTransformMakeScale(maxScale + (minScale - maxScale) * distance, maxScale + (minScale - maxScale) * distance);
v.alpha = (i - offset > 0) ? (1 - distance) : 0; // views that have disappeared behind the screen get no opacity; views still visible fade as their distance increases
v.center = CGPointMake(centerX, frontCenterY + (backCenterY - frontCenterY) * distance);
}
}];
And here's what it looks like, with a couple of randomly-colored views:
do you mean something like this on the right?
If yes, it should be possible. You would have to arrange the Views like on the image and animate them going forwards and backwards. As far as I know aren't there any frameworks for this.
It's called Cover Flow and is also used in iTunes to view the artwork/albums. Apple appear to have bought the technology from a third party and also to have patented it. However if you google for ios cover flow you will get plenty of hits and code to point you in the right direction.
I have not looked but would think that it was maybe in the iOS library but i do not know for sure.
CAAnimation does not provide a mechanism for assigning callback functions other than the standard "animationDidStart:"/"animationDidStop:" methods.
I have a custom UIControl that utilizes 2 CALayers that overlap. The purpose of this control is similar to an old fashioned sonar. The top layer's contents contains an image that gets rotated constantly (call this layer "wand"). Beneath that layer is a "spriteControl" layer that renders blips as the wand passes over them.
The objects that the blips represent are pre-fetched and organized into invisible CAShapeLayers by the spriteControl. I am using a CABasicAnimation to rotate the wand 10 degrees at a time, then utilizing the "animationDidStop:" method to invoke a method on the spriteControl that takes the current rotation value of the wand layer (a.k.a. heading) and animates the alpha setting from 1.0 to 0.0 for simulating the blip in and fade out effect. Finally, the process is started over again indefinitely.
While this approach of using the CAAnimation callbacks ensures that the timing of the wand reaching a "ping" position (i.e. 10deg, 20deg, 270deg, etc) always coincide with the lighting of the blips in the other layer, there is this issue of stopping, recalculating, and starting the animation every 10 degrees.
I could spawn an NSTimer to fire a method that queries the angle of the wand's presentation layer to get the heading value. However, this makes it more difficult to keep the wand and the blip highlighting in sync, and/or cause some to get skipped altogether. This approach is discussed a bit here: How can I callback as a CABasicAnimation is animating?
So my question is whether or not there is anything I can do to improve the performance of the wand layer rotation without reimplementing the control using OpenGL ES. (I realize that this would be easily solved in an OpenGL environment, however, to use it here would require extensive redesign that simply isn't worth it.) While the performance issue is minor, I can't shake the feeling that there is something simple and obvious that I could do that would allow the wand to animate indefinitely without pausing to perform expensive rotation calculations in between.
Here is some code:
- (void)rotateWandByIncrement
{
if (wandShouldStop)
return;
CGFloat newRotationDegree = (wandRotationDegree + WAND_INCREMENT_DEGREES);
if (newRotationDegree >= 360)
newRotationDegree = 0;
CATransform3D rotationTransform = CATransform3DMakeRotation(DEGREES_TO_RADIANS(newRotationDegree), 0, 0, 1);
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"transform"];
animation.toValue = [NSValue valueWithCATransform3D:rotationTransform];
animation.duration = WAND_INCREMENT_DURATION;
animation.fillMode = kCAFillModeForwards;
animation.removedOnCompletion = FALSE;
animation.delegate = self;
[wandLayer addAnimation:animation forKey:#"transform"];
}
- (void)animationDidStart:(CAAnimation *)theAnimation
{
if (wandShouldStop)
return;
NSInteger prevWandRotationDegree = wandRotationDegree - WAND_INCREMENT_DEGREES;
if (prevWandRotationDegree < 0)
prevWandRotationDegree += 360;
// Pulse the spriteControl
[[self spriteControl] pulseRayAtHeading:prevWandRotationDegree];
}
- (void)animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)flag
{
// update the rotation var
wandRotationDegree += WAND_INCREMENT_DEGREES;
if (wandRotationDegree >= 360)
wandRotationDegree = 0;
// This applies the rotation value to the model layer so that
// subsequent animations start where the previous one left off
CATransform3D rotationTransform = CATransform3DMakeRotation(DEGREES_TO_RADIANS(wandRotationDegree), 0, 0, 1);
[CATransaction begin];
[CATransaction setDisableActions:TRUE];
[wandLayer setTransform:rotationTransform];
[CATransaction commit];
//[wandLayer removeAnimationForKey:#"transform"];
[self rotateWandByIncrement];
}
Let's say it takes 10 seconds for the radar to make one complete rotation.
To get the wand to rotate indefinitely, attach a CABasicAnimation to it with its Duration property set to 10 and its RepeatCount property set to 1e100f.
The blips can each be animated using their own instance CAKeyframeAnimation. I won't write the details, but for each blip, you specify an array of opacity values (I assume opacity is how you're fading out the blips) and an array of time percentages (see Apple's documentation).