本文共 5072 字，大约阅读时间需要 16 分钟。

Objective-C实现科赫雪花算法

科赫雪花是一种经典的 fractal，通过递归分割和重复生成形状。以下是实现该算法的详细步骤。

首先，导入必要的头文件：

#import 
   
    #import 
    
   

接下来，实现绘制科赫雪花的函数。该函数将接受绘图上下文和递归深度。

- (void)drawKochWithDepth:(int)depth inContext:(CGContextRef)context{    // 基本形状大小    CGSize squareSize = CGSizeMake(100, 100);        // 初始位置    CGRect squareRect = CGRectMake(0, 0, squareSize.width, squareSize.height);        // 递归绘制    [self recursiveKochWithDepth:depth inContext:context fromRect:squareRect toRect:squareRect];}

递归绘制函数：

- (void)recursiveKochWithDepth:(int)depth inContext:(CGContextRef)context fromRect:(CGRect)fromRect toRect:(CGRect)toRect{    if (depth == 0) {        // 绘制初始正方形        [self drawSquare:context fromRect:fromRect toRect:toRect];        return;    }        // 绘制当前边    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];        // 递归生成下一个级别    [self recursiveKochWithDepth:depth - 1 inContext:context fromRect:fromRect toRect:toRect];        // 绘制下一个分割边    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];        // 绘制当前边    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];        // 递归生成下一个级别    [self recursiveKochWithDepth:depth - 1 inContext:context fromRect:fromRect toRect:toRect];        // 绘制下一个分割边    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];        // 绘制当前边    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];}

绘制正方形：

- (void)drawSquare:(CGContextRef)context fromRect:(CGRect)fromRect toRect:(CGRect)toRect{    // 绘制左上角    [self drawLine:context fromPoint:fromRect.origin toPoint:fromRect.origin];        // 绘制右上角    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];        // 绘制左下角    [self drawLine:context fromPoint:toRect.origin toPoint:toRect.origin];        // 绘制右下角    [self drawLine:context fromPoint:toRect.origin toPoint:fromRect.origin];}

绘制线条：

- (void)drawLine:(CGContextRef)context fromPoint:(CGPoint)start toPoint:(CGPoint)end{    CGPathRef path = CGPathCreateLinearCGPathFromPoints(context, start, end);    CGPathDraw(path, context);    CGPathRelease(path);}

在主函数中初始化并绘制：

int main(int argc, const char *argv){    @autoreleasepool    {        CGContextRef context = CGContextCreateWindow(0, 0, 0, 0, CGRectMake(0, 0, 300, 300), NULL);                // 初始化绘图        [self drawKochWithDepth:4 inContext:context];                CGContextRelease(context);    }    return 0;}

完整代码：

#import 
   
    #import 
    
     @interface KochSnowflake : NSObject{}+ (void)drawKochWithDepth:(int)depth inContext:(CGContextRef)context;- (void)drawSquare:(CGContextRef)context fromRect:(CGRect)fromRect toRect:(CGRect)toRect;- (void)drawLine:(CGContextRef)context fromPoint:(CGPoint)start toPoint:(CGPoint)end;- (void)recursiveKochWithDepth:(int)depth inContext:(CGContextRef)context fromRect:(CGRect)fromRect toRect:(CGRect)toRect;@end@implementation KochSnowflake+ (void)drawKochWithDepth:(int)depth inContext:(CGContextRef)context{    CGSize squareSize = CGSizeMake(100, 100);    CGRect squareRect = CGRectMake(0, 0, squareSize.width, squareSize.height);        [self recursiveKochWithDepth:depth inContext:context fromRect:squareRect toRect:squareRect];}- (void)recursiveKochWithDepth:(int)depth inContext:(CGContextRef)context fromRect:(CGRect)fromRect toRect:(CGRect)toRect{    if (depth == 0) {        [self drawSquare:context fromRect:fromRect toRect:toRect];        return;    }        // 绘制当前边    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];        // 递归生成下一个级别    [self recursiveKochWithDepth:depth - 1 inContext:context fromRect:fromRect toRect:toRect];        // 绘制下一个分割边    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];        // 绘制当前边    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];        // 递归生成下一个级别    [self recursiveKochWithDepth:depth - 1 inContext:context fromRect:fromRect toRect:toRect];        // 绘制下一个分割边    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];        // 绘制当前边    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];}- (void)drawSquare:(CGContextRef)context fromRect:(CGRect)fromRect toRect:(CGRect)toRect{    // 绘制左上角    [self drawLine:context fromPoint:fromRect.origin toPoint:fromRect.origin];        // 绘制右上角    [self drawLine:context fromPoint:fromRect.origin toPoint:toRect.origin];        // 绘制左下角    [self drawLine:context fromPoint:toRect.origin toPoint:toRect.origin];        // 绘制右下角    [self drawLine:context fromPoint:toRect.origin toPoint:fromRect.origin];}- (void)drawLine:(CGContextRef)context fromPoint:(CGPoint)start toPoint:(CGPoint)end{    CGPathRef path = CGPathCreateLinearCGPathFromPoints(context, start, end);    CGPathDraw(path, context);    CGPathRelease(path);}int main(int argc, const char *argv){    @autoreleasepool    {        CGContextRef context = CGContextCreateWindow(0, 0, 0, 0, CGRectMake(0, 0, 300, 300), NULL);                [self drawKochWithDepth:4 inContext:context];                CGContextRelease(context);    }    return 0;}
    
   

转载地址：http://lanfk.baihongyu.com/