我正在尝试找到一种有效,正常或简单的方法来在我的Java程序中实现缓动功能。我已经启用了缓动功能,但是我觉得有一种更有效的方法可以实现。我看不到的那一个,可能是因为隧道视力。这是我的代码;有人可以向我展示我应该做些什么,或为我指明进行研究的方向
public class slide extends JPanel implements Runnable {
Thread ease = new Thread(this);
float total = 0;
float dur;
slide() {
ease.start();
setLayout(null);
}
public float calc(float t, float b, float c, float d) {
return c * t / d + b;
}
public void run() {
while (true) {
try {
if (total < 50) {
total += 1;
} else {
ease.stop();
}
setBounds(400, Math.round(200 * total / 50 + 0), 250, 150);
repaint();
System.out.println(total + " " + dur);
ease.sleep(10);
} catch (Exception e) {
}
}
}
}
我尝试为在线发现的线性缓动函数实现calc()方法,但是它几乎没有用,因为我被迫除非将方程式直接插入到其中就无法使它起作用。
最佳答案
好的,动画是一个相当复杂且深入的主题,在此不做介绍,它还涉及很多我不太了解的数学,因此我们不做大量介绍深度或细节,比我更好的人可以解释它,您可以在网络上阅读它
首先,我们做一些假设...
动画是时间的变化,其中时间是可变的。缓动是(在这种情况下)速度随时间的变化。这意味着动画的速度对于任何给定的时间点都是可变的。
基本上,我们要做的是对所有内容进行“标准化”。也就是说,在动画开始时,时间为0,在结束时为1,介于两者之间的所有其他值都是这两个值之间的分数。
如果您可以这样想,事情就会变得容易得多。因此,根据时间轴上的给定点,您可以决定应该做什么。例如,在50%的时间里,您应该位于起点和终点之间的中间位置
好的,但是这对我们有什么帮助?如果我们要绘制一个缓入缓出动画的图形,它看起来就像...
其中x轴是时间,y轴是速度(两个轴的0和1之间)。因此,在x上的任何给定点上(及时),我们应该能够计算出速度。
现在,我们可以使用贝塞尔曲线脊线/曲线进行一些数学运算,并在时间轴上给定点计算对象的速度。
现在,我直接从Timing Framework借用了大多数代码,但是如果您真的感兴趣,还可以查看Bézier Curves for your Games: A Tutorial
(nb:我实际上确实写过这样的内容,然后两天后,发现Timing Framework已经实现了……是一个有趣的练习……)
现在,关于此实现的重要说明是,它实际上不会返回您物体的速度,但是它将沿时间轴(0-1)返回时间的进展,好吧,这听起来很奇怪,但是它是什么确实允许您做的是沿着时间线计算起点和终点(startValue + ((endValue - startValue) * progress))
之间的当前位置
我不会对此进行详细介绍,因为我真的不懂数学,我只是知道如何应用它,但是基本上,我们计算曲线上的点(x / y),然后将这些值归一化(0-1),以便于查找。interpolate
方法使用二进制搜索来查找给定时间段内最接近的匹配点,然后计算该点的速度/ y位置
public class SplineInterpolator {
private final double points[];
private final List<PointUnit> normalisedCurve;
public SplineInterpolator(double x1, double y1, double x2, double y2) {
points = new double[]{ x1, y1, x2, y2 };
final List<Double> baseLengths = new ArrayList<>();
double prevX = 0;
double prevY = 0;
double cumulativeLength = 0;
for (double t = 0; t <= 1; t += 0.01) {
Point2D xy = getXY(t);
double length = cumulativeLength
+ Math.sqrt((xy.getX() - prevX) * (xy.getX() - prevX)
+ (xy.getY() - prevY) * (xy.getY() - prevY));
baseLengths.add(length);
cumulativeLength = length;
prevX = xy.getX();
prevY = xy.getY();
}
normalisedCurve = new ArrayList<>(baseLengths.size());
int index = 0;
for (double t = 0; t <= 1; t += 0.01) {
double length = baseLengths.get(index++);
double normalLength = length / cumulativeLength;
normalisedCurve.add(new PointUnit(t, normalLength));
}
}
public double interpolate(double fraction) {
int low = 1;
int high = normalisedCurve.size() - 1;
int mid = 0;
while (low <= high) {
mid = (low + high) / 2;
if (fraction > normalisedCurve.get(mid).getPoint()) {
low = mid + 1;
} else if (mid > 0 && fraction < normalisedCurve.get(mid - 1).getPoint()) {
high = mid - 1;
} else {
break;
}
}
/*
* The answer lies between the "mid" item and its predecessor.
*/
final PointUnit prevItem = normalisedCurve.get(mid - 1);
final double prevFraction = prevItem.getPoint();
final double prevT = prevItem.getDistance();
final PointUnit item = normalisedCurve.get(mid);
final double proportion = (fraction - prevFraction) / (item.getPoint() - prevFraction);
final double interpolatedT = prevT + (proportion * (item.getDistance() - prevT));
return getY(interpolatedT);
}
protected Point2D getXY(double t) {
final double invT = 1 - t;
final double b1 = 3 * t * invT * invT;
final double b2 = 3 * t * t * invT;
final double b3 = t * t * t;
final Point2D xy = new Point2D.Double((b1 * points[0]) + (b2 * points[2]) + b3, (b1 * points[1]) + (b2 * points[3]) + b3);
return xy;
}
protected double getY(double t) {
final double invT = 1 - t;
final double b1 = 3 * t * invT * invT;
final double b2 = 3 * t * t * invT;
final double b3 = t * t * t;
return (b1 * points[2]) + (b2 * points[3]) + b3;
}
public class PointUnit {
private final double distance;
private final double point;
public PointUnit(double distance, double point) {
this.distance = distance;
this.point = point;
}
public double getDistance() {
return distance;
}
public double getPoint() {
return point;
}
}
}
如果我们做类似...
SplineInterpolator si = new SplineInterpolator(1, 0, 0, 1);
for (double t = 0; t <= 1; t += 0.1) {
System.out.println(si.interpolate(t));
}
我们得到类似...
0.0
0.011111693284790492
0.057295031944523504
0.16510933001160544
0.3208510585798438
0.4852971690762217
0.6499037832761319
0.8090819765428142
0.9286158775101805
0.9839043020410436
0.999702
好的,现在您可能正在考虑,“请稍等,这是一个线性的过程!”,但是如果您将其绘制成图形,您会发现前三个和后三个值非常接近,而其他值则分布得很近不同程度地得出,这是我们的“进度”值,应该沿着时间轴走多远
所以大约现在,您的头应该快要爆炸了(这就是我的想法)-这就是为什么我说使用框架!
但是,您将如何使用它呢?这是有趣的部分,现在要记住,一切都是可变的,动画的持续时间,对象随时间的速度,滴答声或更新的次数,都是可变的...
这很重要,因为这正是这种力量的源头!例如,如果动画由于某种外部因素而停滞,则此实现方式能够简单地跳过那些“帧”,而不会出现瓶颈和交错现象。这听起来似乎是一件坏事,但是请相信我,这全是愚弄人的眼睛以“思考”某件事正在改变;)
(以下内容类似于8fps,因此非常糟糕)
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Point2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private int startAt = 0;
private int endAt;
private int x = startAt;
private Timer timer;
private SplineInterpolator splineInterpolator;
private long startTime = -1;
private long playTime = 5000; // 5 seconds
public TestPane() {
splineInterpolator = new SplineInterpolator(1, 0, 0, 1);
timer = new Timer(5, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (startTime < 0) {
startTime = System.currentTimeMillis();
}
long now = System.currentTimeMillis();
long duration = now - startTime;
double t = (double) duration / (double) playTime;
if (duration >= playTime) {
t = 1;
}
double progress = splineInterpolator.interpolate(t);
x = startAt + ((int) Math.round((endAt - startAt) * progress));
repaint();
}
});
timer.setInitialDelay(0);
addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
if (!timer.isRunning()) {
startTime = -1;
startAt = 0;
endAt = getWidth() - 10;
timer.start();
}
}
});
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.RED);
g2d.fillRect(x, (getHeight() / 2) - 5, 10, 10);
g2d.dispose();
}
}
public static class SplineInterpolator {
private final double points[];
private final List<PointUnit> normalisedCurve;
public SplineInterpolator(double x1, double y1, double x2, double y2) {
points = new double[]{x1, y1, x2, y2};
final List<Double> baseLengths = new ArrayList<>();
double prevX = 0;
double prevY = 0;
double cumulativeLength = 0;
for (double t = 0; t <= 1; t += 0.01) {
Point2D xy = getXY(t);
double length = cumulativeLength
+ Math.sqrt((xy.getX() - prevX) * (xy.getX() - prevX)
+ (xy.getY() - prevY) * (xy.getY() - prevY));
baseLengths.add(length);
cumulativeLength = length;
prevX = xy.getX();
prevY = xy.getY();
}
normalisedCurve = new ArrayList<>(baseLengths.size());
int index = 0;
for (double t = 0; t <= 1; t += 0.01) {
double length = baseLengths.get(index++);
double normalLength = length / cumulativeLength;
normalisedCurve.add(new PointUnit(t, normalLength));
}
}
public double interpolate(double fraction) {
int low = 1;
int high = normalisedCurve.size() - 1;
int mid = 0;
while (low <= high) {
mid = (low + high) / 2;
if (fraction > normalisedCurve.get(mid).getPoint()) {
low = mid + 1;
} else if (mid > 0 && fraction < normalisedCurve.get(mid - 1).getPoint()) {
high = mid - 1;
} else {
break;
}
}
/*
* The answer lies between the "mid" item and its predecessor.
*/
final PointUnit prevItem = normalisedCurve.get(mid - 1);
final double prevFraction = prevItem.getPoint();
final double prevT = prevItem.getDistance();
final PointUnit item = normalisedCurve.get(mid);
final double proportion = (fraction - prevFraction) / (item.getPoint() - prevFraction);
final double interpolatedT = prevT + (proportion * (item.getDistance() - prevT));
return getY(interpolatedT);
}
protected Point2D getXY(double t) {
final double invT = 1 - t;
final double b1 = 3 * t * invT * invT;
final double b2 = 3 * t * t * invT;
final double b3 = t * t * t;
final Point2D xy = new Point2D.Double((b1 * points[0]) + (b2 * points[2]) + b3, (b1 * points[1]) + (b2 * points[3]) + b3);
return xy;
}
protected double getY(double t) {
final double invT = 1 - t;
final double b1 = 3 * t * invT * invT;
final double b2 = 3 * t * t * invT;
final double b3 = t * t * t;
return (b1 * points[2]) + (b2 * points[3]) + b3;
}
public class PointUnit {
private final double distance;
private final double point;
public PointUnit(double distance, double point) {
this.distance = distance;
this.point = point;
}
public double getDistance() {
return distance;
}
public double getPoint() {
return point;
}
}
}
}
因此,除了
SplineInterpolator
之外,魔术发生在ActionListener
的javax.swing.Timer
内部(还有一些在mouseClicked
事件处理程序中)基本上,这会计算动画的播放时间(
duration
),这将成为我们在时间轴上的标准化时间t
或fraction
值(0-1),然后我们可以使用此时间来计算“ SplineInterpolator
通过时间轴进行“进度”,然后根据对象的开始位置和结束位置之间的差乘以当前“进度”来更新对象的位置if (startTime < 0) {
startTime = System.currentTimeMillis();
}
long now = System.currentTimeMillis();
long duration = now - startTime;
double t = (double) duration / (double) playTime;
if (duration >= playTime) {
t = 1;
}
double progress = splineInterpolator.interpolate(t);
x = startAt + ((int) Math.round((endAt - startAt) * progress));
repaint();
瞧,我们有一个缓入缓出动画!
现在,使用动画框架!太简单了:P
对于“快进/慢进”,可以使用
0, 0, 1, 1
对于“慢进/快出”,可以使用
0, 1, 0, 0
对于“慢进”,可以使用
1, 0, 1, 1
对于“慢速”,可以使用
0, 0, 0, 1
(或至少这些是我使用的值)
做实验,看看你得到什么
关于java - 如何使用线程实现缓动功能,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28335787/