如何使用SpriteKit进行聚光灯效果

Question

在提出此问题之前，我仔细检查了以下问题和示例：

1. Skcropnode在模拟器上工作时无法在设备上工作

2. Swift 3：在SKSpritenode中切一个孔

上面的所有模拟器都很好地工作，但是它在真实设备上不起作用。

我在objetivec中的代码：

SKSpriteNode* mask = [SKSpriteNode spriteNodeWithColor:[UIColor blackColor] size:size];
mask.position = CGPointMake(size.width/2, size.height/2);
mask.name = @"Mask";
mask.alpha = 0.5;
mask.zPosition = 3;
SKSpriteNode* node = [SKSpriteNode spriteNodeWithColor:[UIColor whiteColor] size:size];
node.position = CGPointMake(size.width/2, size.height/2);
node.name = @"circleMask";
node.zPosition = 1;
node.alpha = 1;
SKShapeNode* circleNode = [SKShapeNode shapeNodeWithCircleOfRadius:100/2+20];
circleNode.fillColor = [UIColor whiteColor];
circleNode.lineWidth = 0;
circleNode.alpha = 1;
circleNode.position = CGPointMake(80, -200);
circleNode.name = @"circleNode";
circleNode.zPosition = 1;
circleNode.blendMode = SKBlendModeSubtract;
[node addChild:circleNode];
SKCropNode* cropNode = [[SKCropNode alloc] init];
cropNode.name = @"cropNode";
cropNode.position = CGPointZero;
cropNode.zPosition = 2;
[cropNode setMaskNode: node];
[cropNode addChild:mask];
[scene addChild:cropNode];

我想知道某人是否已经成功地实现了上面类似方法的功能，如果是，请稍微澄清一下，如果不是，您可以发布解决方案吗？非常感谢。

我附加了一张图片，以显示在模拟器和iPhone 6上运行的相同代码：图片显示问题

我的计划：

我将通过编程性创建一个带有孔在正确位置的孔并将其作为SKSpritenode的纹理的UIIMAGE而不是使用Skcropnode。我已经通过Init Skspritenode实现了该功能，并具有创建的UIImage：

-(instancetype)init{
    CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);
    CGRect spotLightRect = CGRectMake(100,100,200,200); // adjust this as desired!
    UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);
    CGContextRef c = UIGraphicsGetCurrentContext();
    UIColor*bColor = [UIColor colorWithRed:0 green:0.0 blue:0 alpha:0.5];
    CGContextSetFillColorWithColor(c, bColor.CGColor);
    CGContextFillRect(c, rect); //the mask
    UIColor*aColor = [UIColor colorWithRed:0 green:0.0 blue:0 alpha:1];
    CGContextSetFillColorWithColor(c, aColor.CGColor);
    CGContextSetBlendMode(c, kCGBlendModeClear);
    CGContextFillEllipseInRect(c, spotLightRect); //the hole
    UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    SKTexture* texture = [SKTexture textureWithImage:image];
    self = [super initWithTexture:texture];
    return self;
}

Answer 1

您的位置和数学有问题，我将分解

离开：

SKSpriteNode* mask = [SKSpriteNode spriteNodeWithColor:[UIColor blackColor] size:size];

删除：

mask.position = CGPointMake(size.width/2, size.height/2);

离开：

mask.name = @"Mask";
mask.alpha = 0.5;

删除：

mask.zPosition = 3;

离开：

SKSpriteNode* node = [SKSpriteNode spriteNodeWithColor:[UIColor whiteColor] size:size];

删除：

node.position = CGPointMake(size.width/2, size.height/2);

离开：

node.name = @"circleMask";

删除：

node.zPosition = 1;

离开：

node.alpha = 1;
SKShapeNode* circleNode = [SKShapeNode shapeNodeWithCircleOfRadius:100/2 + 20];
circleNode.fillColor = [UIColor whiteColor];
circleNode.lineWidth = 0;
circleNode.alpha = 1;
circleNode.position = CGPointMake(80, -200);
circleNode.name = @"circleNode";

删除：

circleNode.zPosition = 1;

离开：

circleNode.blendMode = SKBlendModeSubtract;
[node addChild:circleNode];
SKCropNode* cropNode = [[SKCropNode alloc] init];
cropNode.name = @"cropNode";
cropNode.position = CGPointZero;
cropNode.zPosition = 2;
[cropNode setMaskNode: node];
[cropNode addChild:mask];
[scene addChild:cropNode];

最终结果：

SKSpriteNode* mask = [SKSpriteNode spriteNodeWithColor:[UIColor blackColor] size:size];
mask.name = @"Mask";
mask.alpha = 0.5;
SKSpriteNode* node = [SKSpriteNode spriteNodeWithColor:[UIColor whiteColor] size:size];
node.name = @"circleMask";
node.alpha = 1;
SKShapeNode* circleNode = [SKShapeNode shapeNodeWithCircleOfRadius:100/2+20];
circleNode.fillColor = [UIColor whiteColor];
circleNode.lineWidth = 0;
circleNode.alpha = 1;
circleNode.position = CGPointMake(80, -200);
circleNode.name = @"circleNode";
circleNode.blendMode = SKBlendModeSubtract;
[node addChild:circleNode];
SKCropNode* cropNode = [[SKCropNode alloc] init];
cropNode.name = @"cropNode";
cropNode.position = CGPointZero;
cropNode.zPosition = 2;
[cropNode setMaskNode: node];
[cropNode addChild:mask];
[scene addChild:cropNode];

您现在应该有一个黑屏，带有80，-200