CoreGraphics框架中的CATransform3D類可用于設(shè)定CALayer及其子類的transform屬性板惑，控制layer的縮放龙致、旋轉(zhuǎn)和平移等操作绩脆。

1掰茶、定義:

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

2暇藏、原理:

一個(gè)任意的3D變換都能表示為 乘以一個(gè)4 x 4矩陣 ，即經(jīng)歷一個(gè)4x4的矩陣的變換濒蒋。

3盐碱、解讀:

當(dāng)一個(gè)點(diǎn)（x, y, z）經(jīng)過3D變換后變?yōu)榱硗庖粋€(gè)點(diǎn)（x1, y1, z1）的過程可以表示為：

/* The identity transform: [1 0 0 0; 0 1 0 0; 0 0 1 0; 0 0 0 1]. */
// 單位矩陣
CA_EXTERN const CATransform3D CATransform3DIdentity

// 判斷矩陣是否為3D單位矩陣
CA_EXTERN bool CATransform3DIsIdentity (CATransform3D t)

// 判斷兩個(gè)3D矩陣是否一樣
CA_EXTERN bool CATransform3DEqualToTransform (CATransform3D a, CATransform3D b)

/* Returns a transform that translates by '(tx, ty, tz)':
 * t' =  [1 0 0 0; 0 1 0 0; 0 0 1 0; tx ty tz 1]. */
// 平移
CA_EXTERN CATransform3D CATransform3DMakeTranslation (CGFloat tx, CGFloat ty, CGFloat tz)

/* Returns a transform that scales by `(sx, sy, sz)':
 * t' = [sx 0 0 0; 0 sy 0 0; 0 0 sz 0; 0 0 0 1]. */
// 縮放
CA_EXTERN CATransform3D CATransform3DMakeScale (CGFloat sx, CGFloat sy, CGFloat sz)

/* Returns a transform that rotates by 'angle' radians about the vector
 * '(x, y, z)'. If the vector has length zero the identity transform is returned. */
// 旋轉(zhuǎn)
CA_EXTERN CATransform3D CATransform3DMakeRotation (CGFloat angle, CGFloat x, CGFloat y, CGFloat z)

#prama -----------以上的矩陣變換均是針對(duì)默認(rèn)單位矩陣做出的變換；铩Ｎ屯纭！
#prama -----------即單獨(dú)使用別管你調(diào)用了那個(gè)围橡，調(diào)用了幾次暖混，最后結(jié)果僅僅是針對(duì)單位矩陣做了最后一步的變換！Ｎ淌凇拣播！

/* Translate 't' by '(tx, ty, tz)' and return the result: t' = translate(tx, ty, tz) * t. */
// 在某一3D變換的基礎(chǔ)上平移
CA_EXTERN CATransform3D CATransform3DTranslate (CATransform3D t, CGFloat tx, CGFloat ty, CGFloat tz)

/* Scale 't' by '(sx, sy, sz)' and return the result: t' = scale(sx, sy, sz) * t. */
// 在某一3D變換的基礎(chǔ)上縮放
CA_EXTERN CATransform3D CATransform3DScale (CATransform3D t, CGFloat sx, CGFloat sy, CGFloat sz)

/* Rotate 't' by 'angle' radians about the vector '(x, y, z)' and return the result.
 * If the vector has zero length the behavior is undefined: t' = rotation(angle, x, y, z) * t. */
// 在某一3D變換的基礎(chǔ)上旋轉(zhuǎn)
CA_EXTERN CATransform3D CATransform3DRotate (CATransform3D t, CGFloat angle, CGFloat x, CGFloat y, CGFloat z)

/* Concatenate 'b' to 'a' and return the result: t' = a * b.*/
// 組合兩個(gè)3D變換
CA_EXTERN CATransform3D CATransform3DConcat (CATransform3D a, CATransform3D b)

#prama -----------以上涉及矩陣變換的矩陣可以將多重效果組合使用晾咪！

/* Invert 't' and return the result. Returns the original matrix if 't' has no inverse. */
// 對(duì)某一3D變換結(jié)果取反
CA_EXTERN CATransform3D CATransform3DInvert (CATransform3D t)

/* Return a transform with the same effect as affine transform 'm'. */
// 實(shí)現(xiàn)與仿射變換函數(shù)效果相同的3D變換，即仿射變換轉(zhuǎn)換成3D變換
CA_EXTERN CATransform3D CATransform3DMakeAffineTransform (CGAffineTransform m)

/* Returns true if 't' can be represented exactly by an affine transform. */
// 判斷該3D變換是否可以通過仿射變換精確地表示贮配。因?yàn)樗蟹律渥儞Q都可以用3D變換來表示谍倦，但是反之則不行。
CA_EXTERN bool CATransform3DIsAffine (CATransform3D t)

/* Returns the affine transform represented by 't'. If 't' can not be
 * represented exactly by an affine transform the returned value is undefined. */
// 返回由't'表示的仿射變換泪勒。 如果't'不能通過仿射變換精確地表示昼蛀，則返回的值是未定義的
CA_EXTERN CGAffineTransform CATransform3DGetAffineTransform (CATransform3D t)

@interface NSValue (CATransform3DAdditions)
// NSValue與CATransform3D相互轉(zhuǎn)換的接口
+ (NSValue *)valueWithCATransform3D:(CATransform3D)t;
@property(readonly) CATransform3D CATransform3DValue;

@end

示例一、

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    _blueLayer = [CALayer layer];
    [_blueLayer setBackgroundColor:[UIColor blueColor].CGColor];
    [_blueLayer setFrame:CGRectMake(50, 100, 100, 100)];
    [self.view.layer addSublayer:_blueLayer];
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    if (once) {
        [UIView animateWithDuration:2.0 animations:^{
            _blueLayer.transform = CATransform3DMakeScale(0.5, 0.5, 0.5);
        }];
        once = NO;
    }else{
        [UIView animateWithDuration:2.0 animations:^{
            _blueLayer.transform = CATransform3DMakeTranslation(100, 0, 0);
        }];
        once = YES;
    }
}

示例一效果圖

示例二圆存、

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    _blueLayer = [CALayer layer];
    [_blueLayer setBackgroundColor:[UIColor blueColor].CGColor];
    [_blueLayer setContents:(id)[[UIImage imageNamed:@"lovesick"] CGImage]];
    [_blueLayer setFrame:CGRectMake(50, 100, 200, 350)];
    [self.view.layer addSublayer:_blueLayer];
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    [UIView animateWithDuration:10.0 animations:^{
        CGAffineTransform affineTransform_1 = CGAffineTransformMakeTranslation(200, 0);
        CGAffineTransform affineTransform_2 = CGAffineTransformMakeScale(0.5, 0.5);
        CGAffineTransform affineTransform_all = CGAffineTransformConcat(affineTransform_1, affineTransform_2);
        CATransform3D transform3D_1 = CATransform3DMakeAffineTransform(affineTransform_all);
        CATransform3D transform3D_2 = CATransform3DRotate(transform3D_1, M_PI/2, 0, 0.5, 0.5);
        _blueLayer.transform = transform3D_2;
    }];
}

示例二效果圖

（2曹洽、）其他方法

• 除了上述系統(tǒng)的函數(shù)外還可以直接修改結(jié)構(gòu)體參數(shù)來實(shí)現(xiàn)3D變換。

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    [UIView animateWithDuration:10.0 animations:^{
        CATransform3D transform3D = CATransform3DIdentity;
        transform3D.m41 = 200;
        _blueLayer.transform = transform3D;
    }];
}

直接修改參數(shù)示例

普通轉(zhuǎn)換的矩陣配置影響參數(shù):

在這里特別需要注意的是參數(shù)m34, 這一參數(shù)主要涉及到設(shè)置透視效果辽剧，但是必須要有旋轉(zhuǎn)角度才能顯示出來，否則無(wú)效果税产。