AlmostThere said:
Your pause button should just set an internal variable (e.g. bool) so there is no update when you are calculating new positions for your moving objects. Just cache the time when the update function is called until your app is ready to un-pause, at which point you can start calculating the new positions again.
Your reset button should just call a function that sets your objects to some saved or initial state.
To be moe specific now...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 = 2*3.14*[self generateNumber];
angle2 = 2*3.14*[self generateNumber];
angle3 = 2*3.14*[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
