SpriteKit是否支持精灵/纹理/形状的密集镶嵌，以便它可以自由变形？ [英] Does SpriteKit support dense tessellation of a sprite / texture / shape so it can be warped freely?
问题描述
例如，如果您有蹦床的图像，并且有一个跳跃的角色。然后你想要设想蹦床在中心弯曲的方式。
For example if you have an image of a trampoline, and a character jumping on it. Then you want to animate how the trampoline bends down in the center.
要做到这一点，我必须采用位图并将其应用于密集镶嵌的OpenGL ES网格。然后将纹理应用于它。然后变形网格。
To do this I would have to take a bitmap and apply it to a densely tessellated OpenGL ES mesh. Then apply texture to it. Then deform the mesh.
SpriteKit是否支持此功能，还是只能按原样显示纹理？
Does SpriteKit support this or can it only display textures as-is?
推荐答案
使用iOS 10，添加了 SKWarpGeometry ，允许您变形精灵。使用包含八个控制点的源和目标网格定义扭曲，这些点定义扭曲变换; Sprite Kit将处理曲面细分和其他低级细节。
With iOS 10, SKWarpGeometry has been added that allows you to deform sprites. Warps are defined using a source and destination grid containing eight control points, these points define the warp transform; Sprite Kit will take care of tessellation and other low level details.
您可以直接设置精灵的包裹几何体，或使用SKActions设置变形动画。
You can set the wrap geometry for a sprite directly, or animate warping with SKActions.
SKAction.animate(withWarps: [SKWarpGeometry], times: [NSNumber]) -> SKAction?
SKAction.animate(withWarps: [SKWarpGeometry], times: [NSNumber], restore: Bool) -> SKAction?
SKAction.warp(to: SKWarpGeometry, duration: TimeInterval) -> SKAction?
2016年11月更新
在Xcode 8+上，可以在游乐场中使用以下代码片段：拖动控制点，看看生成的SKSpriteNode会相应地变形。
On Xcode 8+, the following code snippet can be used in a playground: Drag the control points and see the resulting SKSpriteNode get deformed accordingly.
// SpriteKit warp geometry example
// Copy the following in an Xcode 8+ playground
// and make sure your Assistant View is open
//
import UIKit
import PlaygroundSupport
import SpriteKit
let view = SKView(frame: CGRect(x: 0, y: 0, width: 480, height: 320))
let scene = SKScene(size: view.frame.size)
view.showsFPS = true
view.presentScene(scene)
PlaygroundSupport.PlaygroundPage.current.liveView = view
func drawCanvas1(frame: CGRect = CGRect(x: 0, y: 0, width: 200, height: 200)) -> UIImage {
UIGraphicsBeginImageContext(frame.size)
//// Star Drawing
let starPath = UIBezierPath()
starPath.move(to: CGPoint(x: frame.minX + 100.5, y: frame.minY + 24))
starPath.addLine(to: CGPoint(x: frame.minX + 130.48, y: frame.minY + 67.74))
starPath.addLine(to: CGPoint(x: frame.minX + 181.34, y: frame.minY + 82.73))
starPath.addLine(to: CGPoint(x: frame.minX + 149, y: frame.minY + 124.76))
starPath.addLine(to: CGPoint(x: frame.minX + 150.46, y: frame.minY + 177.77))
starPath.addLine(to: CGPoint(x: frame.minX + 100.5, y: frame.minY + 160))
starPath.addLine(to: CGPoint(x: frame.minX + 50.54, y: frame.minY + 177.77))
starPath.addLine(to: CGPoint(x: frame.minX + 52, y: frame.minY + 124.76))
starPath.addLine(to: CGPoint(x: frame.minX + 19.66, y: frame.minY + 82.73))
starPath.addLine(to: CGPoint(x: frame.minX + 70.52, y: frame.minY + 67.74))
starPath.close()
UIColor.red.setFill()
starPath.fill()
UIColor.green.setStroke()
starPath.lineWidth = 10
starPath.lineCapStyle = .round
starPath.lineJoinStyle = .round
starPath.stroke()
let image = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return image
}
class ControlNode : SKShapeNode {
override init() {
super.init()
self.path = CGPath(ellipseIn: CGRect.init(x: 0, y: 0, width: 10, height: 10), transform: nil)
self.fillColor = UIColor.red
self.isUserInteractionEnabled = true
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
typealias UpdateHandler = (ControlNode) -> ()
var positionUpdated: UpdateHandler? = nil
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
self.fillColor = UIColor.yellow
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first, let parent = self.parent {
let pos = touch.location(in: parent).applying(CGAffineTransform(translationX: -5, y: -5))
self.position = pos
positionUpdated?(self)
}
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
self.fillColor = UIColor.red
}
var warpPosition: vector_float2 {
if let parent = self.parent {
let size = parent.frame.size
let pos = self.position.applying(CGAffineTransform(translationX: -size.width/2 + 5, y: -size.height/2 + 5))
return vector_float2(
x: Float(1 + pos.x / size.width),
y: Float(1 + pos.y / size.height)
)
}
return vector_float2(x: 0, y: 0)
}
}
extension SKSpriteNode {
func addControlNode(x: CGFloat, y: CGFloat) -> ControlNode {
let node = ControlNode()
node.position = CGPoint(
x: x * frame.width - frame.width / 2 - 5,
y: y * frame.height - frame.height / 2 - 5
)
self.addChild(node)
return node
}
}
let texture = SKTexture(image: drawCanvas1())
let image = SKSpriteNode(texture: texture)
image.position = CGPoint(x: 200, y: 160)
scene.addChild(image)
let controlPoints: [(x:CGFloat, y:CGFloat)] = [
(0, 0),
(0.5, 0),
(1.0, 0),
(0, 0.5),
(0.5, 0.5),
(1.0, 0.5),
(0, 1.0),
(0.5, 1.0),
(1.0, 1.0),
]
let sourcePositions = controlPoints.map {
vector_float2.init(Float($0.x), Float($0.y))
}
var controlNodes: [ControlNode] = []
controlPoints.forEach { controlNodes.append(image.addControlNode(x: $0.x, y: $0.y)) }
for node in controlNodes {
node.positionUpdated = {
[weak image]
_ in
let destinationPoints = controlNodes.map {
$0.warpPosition
}
image?.warpGeometry = SKWarpGeometryGrid(columns: 2, rows: 2, sourcePositions: sourcePositions, destinationPositions: destinationPoints)
}
}
PS：我提到了 SKWarpGeometry 文档。
PS: I referred to the SKWarpGeometry documentation.
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