So I'm trying to just recreate a bouncing ball app using xcode and C4. What I'm trying to do right now is re-create some of the examples in Dan Shiffmans Nature of Code book in C4.
So far I've managed to create my own class of "Mover" objects that bounce around the screen. That's all working great. The next step was to start "applying some forces" to the movers and play around with that.
I seem to be getting an exception thats crashing the program now that I've added methods to apply force. I put on exception breakpoints and this line in C4Control.m is where it stops:
if(_animationDuration == 0.0f) super.center = center;
Looking into this more, I notice that neither super.center or center properties have a value assigned to them (both of NaN). I'm not sure what's causing this? This seemed to start once I decided to set each Movers initial velocity/accel to 0 and only assign "fores" (C4Vectors for wind and gravity) to create motion in these objects. When I comment out the 2 lines that apply each force, the problem goes away.
This is the implementation of my mover class:
//Init Method
- (id)initWithPoint:(CGPoint)point andCanvasController:(C4CanvasController *)canvasController {
self = [super init];
if (self) {
canvasFrame = CGPointMake(canvasController.canvas.width,
canvasController.canvas.height);
diam = [C4Math randomInt:70];
mass = diam * 0.5f;
CGRect ellipseFrame = CGRectMake(0, 0, diam, diam);
[self ellipse:ellipseFrame];
self.lineWidth = 0.0f;
self.fillColor = [UIColor colorWithRed:[C4Math randomInt:60]/60
green:[C4Math randomInt:100]/100.0f
blue:0.9f
alpha:0.3f];
int foo = arc4random() % (int)([canvasController.canvas height]);
int bar = arc4random() % (int)([canvasController.canvas width]);
self.location = [C4Vector vectorWithX:foo
Y:bar
Z:0.0f];
self.origin = self.location.CGPoint;
self.accel = [C4Vector vectorWithX:0.00f Y:0.0f Z:0.0f];
self.vel = [C4Vector vectorWithX:0.00f Y:0.0f Z:0.0f];
}
return self;
}
//Method to calculate updated mover position
-(void)update{
[self.vel add:self.accel];
[self.location add:self.vel];
self.origin = self.location.CGPoint;
[self.accel multiplyScalar:0];
[self checkBounds];
}
//Checking if mover has reached edge of screen
-(void)checkBounds{
if (self.origin.x > canvasFrame.x - diam){
self.location.x = canvasFrame.x - diam;
self.vel.x *= -1;
}
else if (self.origin.x < 0){
self.vel.x *= -1;
self.location.x = 0;
}
if(self.origin.y > canvasFrame.y - diam){
self.location.y = canvasFrame.y - diam;
self.vel.y *= -1;
}
else if(self.origin.y < 0){
self.vel.y *= -1;
self.location.y = 0;
}
}
//Start C4Timer to run update every 1/60th of a second
- (void) run{
updateTimer = [C4Timer automaticTimerWithInterval:1/60.0f
target:self
method:@"update"
repeats:YES];
}
//Calculate a force to apply to mover
- (void)applyForce:(C4Vector *)force{
[force divideScalar:mass];
[self.accel add:force];
}
In my C4WorkSpace.m file:
#import "C4Workspace.h"
#import "Mover.h"
@implementation C4WorkSpace{
Mover *testMover;
NSMutableArray *moverArray;
}
-(void)setup {
C4Vector *gravity = [C4Vector vectorWithX:0.01f Y:0.0 Z:0.0f];
C4Vector *wind = [C4Vector vectorWithX:0 Y:0.4 Z:0];
moverArray = [[NSMutableArray alloc]init];
//Not using foo/bar variables right now, but usually use them to create CGPoint p
//int foo = arc4random() % (int)([self.canvas height]);
//int bar = arc4random() % (int)([self.canvas width]);
for (int i = 0; i < 500; i++) {
CGPoint p = CGPointMake(0,0);
Mover *m = [[Mover alloc]initWithPoint:p andCanvasController:self];
[moverArray addObject:m];
}
for (Mover *m in moverArray){
[self addShape:m];
[m run];
[m applyForce:gravity];
[m applyForce:wind];
}
}
@end
Sorry for how long this was, any and all help is much appreciated!
