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drawing smooth curves methods needed


drawing smooth curves methods needed  using -'iphone,objective-c,ios,ipad,bezier-curve'

Like everyone before has asked, how do you smooth a set of points in an iOS drawing app WHILE MOVING? I have tried UIBezierpaths but all I get are jagged ends where they intersect, when I just shift the points 1,2,3,4 - 2,3,4,5. I have heard of spline curves and all the other types. I am quite new to iPhone programming and do not understand how to program it in my quartz drawing app. A solid example would be greatly appreciated, I have spent weeks running in circles and I can never seem to find any iOS code for this task. Most of the posts just link to a java simulation or pages on wikipedia about curve fitting which does nothing for me. Also I do not want to switch to openGL ES. I hope someone can finally provide code to answer this circulating question.

Thank You, Happy New Year!!!

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This was my code for the UIBezierPath which left edges at intersection///

UPDATED TO AN ANSWER BELOW

#define VALUE(_INDEX_) [NSValue valueWithCGPoint:points[_INDEX_]]
#define POINT(_INDEX_) [(NSValue *)[points objectAtIndex:_INDEX_] CGPointValue]

- (UIBezierPath*)smoothedPathWithGranularity:(NSInteger)granularity
{
    NSMutableArray *points = [(NSMutableArray*)[self pointsOrdered] mutableCopy];

    if (points.count < 4) return [self bezierPath];

    // Add control points to make the math make sense
    [points insertObject:[points objectAtIndex:0] atIndex:0];
    [points addObject:[points lastObject]];

    UIBezierPath *smoothedPath = [self bezierPath];
    [smoothedPath removeAllPoints];

    [smoothedPath moveToPoint:POINT(0)];

    for (NSUInteger index = 1; index < points.count - 2; index++)
    {
        CGPoint p0 = POINT(index - 1);
        CGPoint p1 = POINT(index);
        CGPoint p2 = POINT(index + 1);
        CGPoint p3 = POINT(index + 2);

        // now add n points starting at p1 + dx/dy up until p2 using Catmull-Rom splines
        for (int i = 1; i < granularity; i++)
        {
            float t = (float) i * (1.0f / (float) granularity);
            float tt = t * t;
            float ttt = tt * t;

            CGPoint pi; // intermediate point
            pi.x = 0.5 * (2*p1.x+(p2.x-p0.x)*t + (2*p0.x-5*p1.x+4*p2.x-p3.x)*tt + (3*p1.x-p0.x-3*p2.x+p3.x)*ttt);
            pi.y = 0.5 * (2*p1.y+(p2.y-p0.y)*t + (2*p0.y-5*p1.y+4*p2.y-p3.y)*tt + (3*p1.y-p0.y-3*p2.y+p3.y)*ttt);
            [smoothedPath addLineToPoint:pi];
        }

        // Now add p2
        [smoothedPath addLineToPoint:p2];
    }

    // finish by adding the last point
    [smoothedPath addLineToPoint:POINT(points.count - 1)];

    return smoothedPath;
}
- (PVPoint *)pointAppendingCGPoint:(CGPoint)CGPoint
{
    PVPoint *newPoint = [[PVPoint alloc] initInsertingIntoManagedObjectContext:[self managedObjectContext]];
    [newPoint setCGPoint:CGPoint];
    [newPoint setOrder:[NSNumber numberWithUnsignedInteger:[[self points] count]]];
    [[self mutableSetValueForKey:@"points"] addObject:newPoint];
    [(NSMutableArray *)[self pointsOrdered] addObject:newPoint];
    [[self bezierPath] addLineToPoint:CGPoint];
    return [newPoint autorelease];

    if ([self bezierPath] && [pointsOrdered count] > 3)
    {
        PVPoint *control1 = [pointsOrdered objectAtIndex:[pointsOrdered count] - 2];
        PVPoint *control2 = [pointsOrdered objectAtIndex:[pointsOrdered count] - 1];
        [bezierPath moveToPoint:[[pointsOrdered objectAtIndex:[pointsOrdered count] - 3] CGPoint]];
        [[self bezierPath] addCurveToPoint:CGPoint controlPoint1:[control1 CGPoint] controlPoint2:[control2 CGPoint]];

    }

}

- (BOOL)isComplete { return [[self points] count] > 1; }

- (UIBezierPath *)bezierPath
{
    if (!bezierPath)
    {
        bezierPath = [UIBezierPath bezierPath];
        for (NSUInteger p = 0; p < [[self points] count]; p++)
        {
            if (!p) [bezierPath moveToPoint:[(PVPoint *)[[self pointsOrdered] objectAtIndex:p] CGPoint]];
            else [bezierPath addLineToPoint:[(PVPoint *)[[self pointsOrdered] objectAtIndex:p] CGPoint]];
        }
        [bezierPath retain];
    }

    return bezierPath;
}

- (CGPathRef)CGPath
{
    return [[self bezierPath] CGPath];
}



    

asked Sep 29, 2015 by yashwantpinge
0 votes
14 views



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