CATransform3D

1. 首先明白CATransform3D是个什么东西,是一个四维变换矩阵,描述3d空间

struct CATransform3D
{
  CGFloat m11, m12, m13, m14;
  CGFloat m21, m22, m23, m24;
  CGFloat m31, m32, m33, m34;
  CGFloat m41, m42, m43, m44;
};

• 每个参数的含义分别是:

m11：x轴方向进行缩放

m12：和m21一起决定z轴的旋转

m13:和m31一起决定y轴的旋转

m14:

m21:和m12一起决定z轴的旋转

m22:y轴方向进行缩放

m23:和m32一起决定x轴的旋转

m24:

m31:和m13一起决定y轴的旋转

m32:和m23一起决定x轴的旋转

m33:z轴方向进行缩放

m34:透视效果m34= -1/D，D越小，透视效果越明显，必须在有旋转效果的前提下，才会看到透视效果

m41:x轴方向进行平移

m42:y轴方向进行平移

m43:z轴方向进行平移

m44:初始为1

2.一些常用的方法

//初始化一个transform3D对象，不做任何变换
const CATransform3D CATransform3DIdentity;
//判断一个transform3D对象是否是初始化的对象
bool CATransform3DIsIdentity (CATransform3D t);
//比较两个transform3D对象是否相同
bool CATransform3DEqualToTransform (CATransform3D a, CATransform3D b);
//将两个 transform3D对象变换属性进行叠加，返回一个新的transform3D对象
CATransform3D CATransform3DConcat (CATransform3D a, CATransform3D b);

• 不带make和带make的区别是,没有Make的是叠加原理
  带make的可以使用 CATransform3DConcat (CATransform3D a, CATransform3D b);达到和不带Make的一样的效果

//返回一个平移变换的transform3D对象 tx，ty，tz对应x，y，z轴的平移
CATransform3D CATransform3DMakeTranslation (CGFloat tx, CGFloat ty, CGFloat tz);
//在某个transform3D变换的基础上进行平移变换，t是上一个transform3D，其他参数同上
CATransform3D CATransform3DTranslate (CATransform3D t, CGFloat tx, CGFloat ty, CGFloat tz);

//缩放
CATransform3D CATransform3DMakeScale (CGFloat sx, CGFloat sy,
    CGFloat sz)
CATransform3D CATransform3D CATransform3DScale (CATransform3D t, CGFloat sx,
                                      CGFloat sy, CGFloat sz)

//旋转
CATransform3D CATransform3DMakeRotation (CGFloat angle, CGFloat x,
    CGFloat y, CGFloat z)
 CATransform3DRotate (CATransform3D t, CGFloat angle,
    CGFloat x, CGFloat y, CGFloat z)
//反转't'并返回结果。 如果't'没有逆，返回原始矩阵。
CATransform3D CATransform3DInvert (CATransform3D t)

• 代码案列

    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];
    CATransform3D t0 = CATransform3DIdentity;
    NSValue *value1 = [NSValue valueWithCATransform3D:t0];
    animation.fromValue = value1;
    
    CATransform3D t1 = CATransform3DMakeScale(0.5, 0.5, 1.0);
    NSValue *value2 = [NSValue valueWithCATransform3D:t1];
    animation.toValue = value2;
    
    animation.duration = 2.0;
    animation.autoreverses = YES;
    animation.repeatCount = 2;
    animation.removedOnCompletion = NO;
    //不加这句话,执行完动画会回到原来
    self.imageView.layer.transform = t1;
    [self.imageView.layer addAnimation:animation forKey:nil];

• 不带make的效果叠加

 CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];
    CATransform3D t0 = CATransform3DIdentity;
    NSValue *value1 = [NSValue valueWithCATransform3D:t0];
    animation.fromValue = value1;
    
    //不带make的效果叠加
    CATransform3D t1 = CATransform3DScale(t0, 0.5, 0.5, 1.0);
    t1 = CATransform3DTranslate(t1, 100, 100, 0);
    t1 = CATransform3DRotate(t1, M_PI_4, 0, 1, 0);
    NSValue *value2 = [NSValue valueWithCATransform3D:t1];
    animation.toValue = value2;
    
    animation.duration = 0.5;
    animation.autoreverses = NO;
    animation.removedOnCompletion = NO;
    //不加这句话,执行完动画会回到原来
    self.imageView.layer.transform = t1;
    [self.imageView.layer addAnimation:animation forKey:nil];

• 带make的叠加

    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];
    CATransform3D t0 = CATransform3DIdentity;
    NSValue *value1 = [NSValue valueWithCATransform3D:t0];
    animation.fromValue = value1;
    
    //带make的叠加
    CATransform3D t1 = CATransform3DMakeScale( 0.5, 0.5, 1.0);
    CATransform3D t2 = CATransform3DMakeTranslation(100, 100, 0);
    CATransform3D t3 = CATransform3DMakeRotation(M_PI_4, 0, 1, 0);

    CATransform3D t4 = CATransform3DConcat(t1, t2);
    CATransform3D t5 = CATransform3DConcat(t4, t3);
    
    NSValue *value2 = [NSValue valueWithCATransform3D:t5];
    animation.toValue = value2;
    
    animation.duration = 0.5;
    animation.autoreverses = NO;
    animation.removedOnCompletion = NO;
    //不加这句话,执行完动画会回到原来
    self.imageView.layer.transform = t5;
    [self.imageView.layer addAnimation:animation forKey:nil];

• m34使用方法,透视效果m34= -1/D，D越小，透视效果越明显，必须在有旋转效果的前提下，才会看到透视效果

    CATransform3D t3 = CATransform3DIdentity;
    t3.m34 = -1/100.0;
    t3 = CATransform3DRotate(t3,M_PI_4, 0, 1, 0);

    //不加这句话,执行完动画会回到原来
    self.imageView.layer.transform = t3;

• 旋转反转变换

  UIImageView * imageView = [[UIImageView alloc]initWithFrame:CGRectMake(100, 100, 100, 100)];
    imageView.image = [UIImage imageNamed:@"屏幕快照 2015-12-06 下午3.27.15.png"];
    imageView.layer.transform = CATransform3DMakeRotation(M_PI/4, 0, 0, 1);
    [self.view addSubview:imageView];
    
    UIImageView * newImageView = [[UIImageView alloc]initWithFrame:CGRectMake(100, 300, 100, 100)];
    newImageView.image=[UIImage imageNamed:@"屏幕快照 2015-12-06 下午3.27.15.png"];
    [self.view addSubview:newImageView];
    CATransform3D trans = CATransform3DMakeRotation(M_PI/4, 0, 0, 1);
    trans = CATransform3DInvert(trans);
    
    newImageView.layer.transform =trans;

3.CATransform和CGAffineTransform的区别,前者用于3d变换,作用在layer上,配合coreAnimation使用,后者是UIview的2d变化,作用在view上

//将一个CGAffinrTransform转化为CATransform3D
CATransform3D CATransform3DMakeAffineTransform (CGAffineTransform m);
//判断一个CATransform3D是否可以转换为CAAffineTransform
bool CATransform3DIsAffine (CATransform3D t);
//将CATransform3D转换为CGAffineTransform
CGAffineTransform CATransform3DGetAffineTransform (CATransform3D t);