我目前正在开发一款2D Android 游戏,
在这个游戏中,一个ViewObject(Bitmap)在Parabola Path上在屏幕上移动,就像在这个图像中一样,但是这个路径是静态的,静态路径正在穿过在 Canvas 上用手指绘图,
与签名图相同。
此静态路径上的位图移动代码是
//animation step
private static int iMaxAnimationStep = 900;
private int iCurStep = 0;
private Path ptCurve = new Path(); //curve
private PathMeasure pm; //curve measure
private float fSegmentLen; //curve segment length
//init smooth curve
PointF point = aPoints.get(0);
ptCurve.moveTo(point.x, point.y);
for(int i = 0; i < aPoints.size() - 1; i++){
point = aPoints.get(i);
PointF next = aPoints.get(i+1);
ptCurve.quadTo(point.x, point.y, (next.x + point.x) / 2, (point.y + next.y) / 2);
}
pm = new PathMeasure(ptCurve, false);
fSegmentLen = pm.getLength() / iMaxAnimationStep;//20 animation steps
//animate the Bitmap
Matrix mxTransform = new Matrix();
if (iCurStep <= iMaxAnimationStep)
{
pm.getMatrix(fSegmentLen * iCurStep, mxTransform,
PathMeasure.POSITION_MATRIX_FLAG);
mxTransform.preTranslate(-Bitmap.getWidth(), -Bitmap.getHeight());
canvas.drawBitmap(Bitmap, mxTransform, null);
iCurStep++; //advance to the next step
mPauseViewHandler.post(mPauseViewRunnable);
} else {
iCurStep = 0;
}
但我的问题是我想在动态路径(抛物线)上移动这个ViewObject(Bitmap) 并且动态曲线路径适用于任何设备。
我已经搜索了 Lot,但找不到如何获得动态路径(抛物线曲线)的解决方案。
救命啊!如果您对这篇文章有任何解决方案、建议、想法和教程,我们将不胜感激。
最佳答案
根据您的屏幕尺寸填充 aPoints
数组,并根据这些点获得抛物线路径,这非常简单。我已经删除了所有位图/动画代码,下面的代码将计算路径并将其绘制在屏幕上。
我们需要一个新变量来设置屏幕中需要多少条曲线。如果您愿意,可以很容易地更改数学并改为定义曲线的大小。
private int numberOfCurves = 5;
这样很容易为每个抛物线计算 3 个点:
public void calculatePoints(){
float w = v.getWidth(); //Screen width
float h = v.getHeight(); //Screen height
float curveSize = w/numberOfCurves; // Curve size
float curveHeight = (h/100) * 20; //80% of the screen size
Log.d(TAG,"h:"+h +" - w:" + w);
float lastX = 0; //last used X coordinate
for (int i=0;i<numberOfCurves;i++){ //for each curve we'll need 3 points
float newX = lastX + curveSize;
PointF p = new PointF(lastX, h); //first point is the last point
PointF p1 = new PointF((lastX + newX)/2, curveHeight); //the middle point is halfway between the last and the new point
PointF p2 = new PointF(newX,h); // the new point is last point + the size of our curve
aPoints.add(p); //fill in the array
aPoints.add(p1);
aPoints.add(p2);
lastX = newX; //update last point
}
//log our points
for (PointF p : aPoints){
Log.d(TAG,p.x +"-"+p.y);
}
}
现在我们有一组定义每条抛物线的点,我们需要绘制它。不要使用 quadTo,而是使用 cubicTo .它需要 3 个点并绘制连接它们的曲线。将其放在 Draw 上,您就可以在屏幕上绘制抛物线。
private Path ptCurve = new Path(); //curve
@Override
public void onDraw(Canvas canvas) {
calculatePoints();
Log.d(TAG,"DRAWING");
PointF point = aPoints.get(0);
ptCurve.moveTo(point.x, point.y);
for(int i = 0; i < aPoints.size() - 1; i+=3){
point = aPoints.get(i);
PointF middle = aPoints.get(i+1);
PointF next = aPoints.get(i+2);
ptCurve.cubicTo(point.x, point.y, middle.x,middle.y, next.x , next.y);
}
canvas.drawPath(ptCurve, paint);
}
因此,您的 ptCurve
变量现在填充了一条抛物线路径,其中包含您之前定义的尽可能多的曲线,并且它适用于任何屏幕尺寸。
关于android - 我们如何定义 ViewObject(位图)的动态(抛物线)路径,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/16932668/