CocoaDev

I am posting this program I wrote sometime back, which makes a triangle using OpenGl. There are three text boxes, where the user can enter the initial velocities for each of the three triangle nodes. Then I specify the number of time steps this triangle should redraw itself doing what I ask it to do in the program (which normally is to change its angle randomly and move eaach node). I am using a button to start this process after I specify the velocities and the timesteps. This button is a “toggle” type NSButton which has its alternate title set to Pause. however once I start the program and once the program start redrawing the triangle, I cannot stop it in between. I am looking for ways in which I might be able to discontinue this operation/program by pressing the button again when it displays the “pause” state

#import "Triangle.h" #include <stdlib.h> #include <time.h> #include <OpenGL/gl.h>

@implementation Triangle

• (id) initWithCoder: (NSCoder *) coder { NSOpenGLPixelFormatAttribute attrs[] = { NSOpenGLPFADoubleBuffer, nil };

  NSOpenGLPixelFormat* pixFmt ; long swapInterval ;

  self = [super initWithCoder: coder] ; ver1.x = 0.556; ver1.y = 0.2; ver2.x = -0.343; ver2.y = 0.443; ver3.x = 0.02; ver3.y = 0.66; vel1 = 0.; vel2 = 0.; vel3 = 0.; steps = 0; flipped = NO; a1 = time(NULL); r = 0.0; g = 1.0; b = 0.0; angle1 = 23.14[self generateNumber]; angle2 = 23.14[self generateNumber]; angle3 = 23.14[self generateNumber];

  pixFmt = [[NSOpenGLPixelFormat alloc] initWithAttributes: attrs] ; [self setPixelFormat: pixFmt] ; swapInterval = 1 ; self openGLContext] setValues: &swapInterval forParameter: [[NSOpenGLCPSwapInterval ] ; return self ; }

-(void) awakeFromNib { [velocity1 setFloatValue:vel1]; [velocity2 setFloatValue:vel2]; [velocity3 setFloatValue:vel3]; [timesteps setFloatValue:steps]; }

-(float)generateNumber { srand(a1); int a2,b2; float c; a2 = rand(); a1 = a2; b2 = RAND_MAX; float tempa, tempb; tempa = a2; tempb = b2; c = tempa/tempb; return c; }

-(NSPoint)boundaryCondition:(NSPoint)var { NSPoint tempPoint; tempPoint.x = var.x; tempPoint.y = var.y;

if (tempPoint.x < -1.0) 
{tempPoint.x = tempPoint.x +2.0;
flipped = YES;}
if (tempPoint.x > 1.0)
{ tempPoint.x = tempPoint.x -2.0;
flipped = YES;}

if (tempPoint.y < -1.0) 
{ tempPoint.y = 2.0+ tempPoint.y;
flipped = YES;}
if (tempPoint.y > 1.0)
{ tempPoint.y = tempPoint.y - 2.0;
flipped = YES;}

return tempPoint;	 }

• (IBAction)move:(id)sender { vel1 = [velocity1 floatValue]; vel2 = [velocity2 floatValue]; vel3 = [velocity3 floatValue]; steps = [timesteps floatValue]; int t;

for (t=0; t<=steps; t++) { float angle, interval; flipped = NO; interval =0.005;

NSLog(@"Time Step %d", t);

angle1 += [self generateNumber]*0.01;
ver1.x = ver1.x + interval*vel1*cos(angle1);
ver1.y = ver1.y + interval*vel1*sin(angle1);
ver1 = [self boundaryCondition:ver1];

angle2 += [self generateNumber]*0.01;
ver2.x = ver2.x + interval*vel2*cos(angle2);
ver2.y = ver2.y + interval*vel2*sin(angle2);
ver2 = [self boundaryCondition:ver2];

angle3 += [self generateNumber]*0.01;
ver3.x = ver3.x + interval*vel3*cos(angle3);
ver3.y = ver3.y + interval*vel3*sin(angle3);
ver3 = [self boundaryCondition:ver3];

[self lockFocus];
[self drawRect:[self frame]];
[self unlockFocus];
} }

-(void)drawRect:(NSRect)rect { if (flipped == YES) { r = [self generateNumber]; b = [self generateNumber]; g = [self generateNumber]; }

glClearColor( 0, 0, 0, 0 ) ;
glClear( GL_COLOR_BUFFER_BIT ) ;
glColor3f( r,g,b ) ;
glBegin( GL_TRIANGLES) ;
{
    glVertex3f( ver1.x, ver1.y, 0.0 ) ;
    glVertex3f( ver2.x, ver2.y, 0.0 ) ;
    glVertex3f( ver3.x , ver3.y, 0.0 ) ;
}
glEnd() ;
glFinish() ;
[[self openGLContext] flushBuffer]; } @end