Android Game development Collision Detection (rectangular collision, circular collision, pixel collision) _android

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The principle of rectangular collision : Four kinds of two rectangular positions not in these four cases are collisions

Circular Collision principle: Using the distance between the two centers to determine. When the distance between two centers is less than the radius of the collision.

Pixel Collision principle: Not applicable traversal all pixel detection too much

Multi-Rectangular collision principle: To set up multiple rectangular collision detection areas to detect the position relationship between a collision rectangular array and another colliding rectangular array.

Rectangular Collision Code:

public class Mysurfaceview extends Surfaceview implements Callback, Runnable {private Surfaceholder sfh;
  Private Paint Paint;
  private Thread th;
  Private Boolean flag;
  Private Canvas Canvas;
  private int screenw, screenh;
  Defines a two-rectangle wide-high coordinate private int x1 = ten, y1 =, W1 =, H1 = 40;
  private int x2 = y2 =, W2 =, H2 = 40;

  Easy to see if there is a collision setting an identity bit private Boolean iscollsion;
    /** * Surfaceview initialization function/public Mysurfaceview {super (context);
    SFH = This.getholder ();
    Sfh.addcallback (this);
    Paint = new paint ();
    Paint.setcolor (Color.White);
    Paint.setantialias (TRUE);
  Setfocusable (TRUE); /** * Surfaceview View creation, response to this function/@Override public void surfacecreated (Surfaceholder holder) {screenw = t
    His.getwidth ();
    Screenh = This.getheight ();
    Flag = true;
    instance thread th = new thread (this);
  Start thread Th.start (); /** * Game drawing/public void Mydraw () {try {canvas = Sfh.lockcanvas ();
        if (canvas!= null) {Canvas.drawcolor (color.black);
          if (iscollsion) {paint.setcolor (color.red);
          Paint.settextsize (20); Canvas.drawtext ("collision!
        ", 0, paint);
        else {paint.setcolor (color.white);
        //Draw two rectangular canvas.drawrect (x1, y1, x1 + W1, y1 + h1, paint);
      Canvas.drawrect (x2, y2, x2 + w2, y2 + h2, paint); } catch (Exception e) {//Todo:handle Exception} finally {if (canvas!= null) sfh.unlock
    Canvasandpost (canvas); /** * Touchscreen Event Monitor/@Override public boolean ontouchevent (Motionevent event) {//Let rectangle 1 move with touchscreen position x1 =
    (int) Event.getx ()-w1/2;
    y1 = (int) event.gety ()-h1/2;
    if (Iscollsionwithrect (x1, y1, W1, H1, X2, y2, W2, H2)) {iscollsion = true;
    else {iscollsion = false;
  return true; /** * Button Event Monitor/@Override public boolean onKeyDown (int KeyCode, KeyEvent event) {return Super.onkeydown (KeyCode, event); /** * Game logic/private void logic () {} public boolean iscollsionwithrect (int x1, int y1, int w1, int H1
    , int x2, int y2, int w2, int h2) {if (x1 >= x2 && x1 >= x2 + W2) {return false;
    else if (x1 <= x2 && x1 + W1 <= x2) {return false;
    else if (y1 >= y2 && y1 >= y2 + H2) {return false;
    else if (y1 <= y2 && y1 + h1 <= y2) {return false;
  return true;
      @Override public void Run () {while (flag) {Long start = System.currenttimemillis ();
      Mydraw ();
      Logic ();
      Long end = System.currenttimemillis ();
        try {if (End-start <) {Thread.Sleep (End-start));
      } catch (Interruptedexception e) {e.printstacktrace (); /** * Surfaceview view state changed in response to this function/* @Override public voidSurfacechanged (surfaceholder holder, int format, int width, int height) {}/** * Surfaceview View dies, respond to this function * *
  Override public void surfacedestroyed (Surfaceholder holder) {flag = false;

 }
}

Round Collision Code:

public class Mysurfaceview extends Surfaceview implements Callback, Runnable {private Surfaceholder sfh;
  Private Paint Paint;
  private Thread th;
  Private Boolean flag;
  Private Canvas Canvas;
  private int screenw, screenh;
  Defines two rounded radii with coordinates private int r1 = r2 = 20;
  private int x1 = Y1 = +, x2 = $, y2 = 100;

  Defines a collision identifier bit private Boolean iscollision;
    /** * Surfaceview initialization function/public Mysurfaceview {super (context);
    SFH = This.getholder ();
    Sfh.addcallback (this);
    Paint = new paint ();
    Paint.setcolor (Color.White);
    Paint.setantialias (TRUE);
  Setfocusable (TRUE); /** * Surfaceview View creation, response to this function/@Override public void surfacecreated (Surfaceholder holder) {screenw = t
    His.getwidth ();
    Screenh = This.getheight ();
    Flag = true;
    instance thread th = new thread (this);
  Start thread Th.start ();
      /** * Game drawing/public void Mydraw () {try {canvas = Sfh.lockcanvas ();if (canvas!= null) {Canvas.drawcolor (color.black);
          if (iscollision) {paint.setcolor (color.red);
          Paint.settextsize (20);
        Canvas.drawtext ("collision!", 0, paint);
        else {paint.setcolor (color.white);
        } canvas.drawcircle (x1, y1, r1, paint);
      Canvas.drawcircle (x2, y2, r2, paint); } catch (Exception e) {//Todo:handle Exception} finally {if (canvas!= null) sfh.unlock
    Canvasandpost (canvas); 
    /** * Touchscreen Event Monitor/@Override public boolean ontouchevent (Motionevent event) {x1 = (int) event.getx ();
    y1 = (int) event.gety ();
    if (iscollisionwithcircle (x1, y1, x2, y2, R1, R2)) {iscollision = true;
    else {iscollision = false;
  return true;
   /** * Circular collision * @param X1 Circle 1 's Center x coordinate * @param y1 Circle 2 's Center x coordinate * @param x2 Circle 1 's Center y coordinate * @param y2 Circle 2 's Center y-coordinate * @param R1 Circle 1 radius * @param R2 Circle 2 radius *return */Private Boolean iscollisionwithcircle (int x1, int y1, int x2, int y2, int r1, int r2) {//math.sqrt: Open squared 
      Math.pow (double x, double y): X's Y-square if (Math.sqrt (Math.pow (X1-X2, 2) + Math.pow (Y1-y2, 2)) <= R1 + R2) {
    If the center distance of two circles is less than or equal to two circle radius, the collision return true is considered;
  return false; /** * Button Event Monitor/@Override public boolean onKeyDown (int keycode, keyevent event) {return Super.onkeydow
  N (keycode, event); /** * Game logic/private void logic () {} @Override public void Run () {while (flag) {Long STA
      RT = System.currenttimemillis ();
      Mydraw ();
      Logic ();
      Long end = System.currenttimemillis ();
        try {if (End-start <) {Thread.Sleep (End-start));
      } catch (Interruptedexception e) {e.printstacktrace ();  /** * Surfaceview view state changed in response to this function */@Override public void surfacechanged (surfaceholder holder, int ForMat, int width, int height) {}/** * Surfaceview View dies, respond to this function */@Override public void surfacedestroyed (Surf
  Aceholder holder) {flag = false;

 }
}

Multi-Rectangular collision code

public class Mysurfaceview extends Surfaceview implements Callback, Runnable {private Surfaceholder sfh;
  Private Paint Paint;
  private Thread th;
  Private Boolean flag;
  Private Canvas Canvas;
  private int screenw, screenh;
  Defines the wide-high coordinates of two rectangular graphics private int rectX1 = ten, rectY1 = ten, rectW1 =, rectH1 = 40;
  private int rectX2 = RectY2 =, rectW2 =, rectH2 = 40;
  Easy to see if there is a collision setting an identity bit private Boolean iscollsion;
  Defines the rectangular array of collisions for the first rectangle private Rect ClipRect1 = new Rect (0, 0, 15, 15);
  Private Rect ClipRect2 = new Rect (rectw1-15, recth1-15, rectW1, rectH1);
  Private rect[] ArrayRect1 = new rect[] {clipRect1, clipRect2};
  Defines a rectangular array of collisions for the second rectangle private Rect clipRect3 = new Rect (0, 0, 15, 15);
  Private Rect ClipRect4 = new Rect (rectw2-15, recth2-15, rectW2, rectH2);

  Private rect[] ArrayRect2 = new rect[] {clipRect3, clipRect4};
    /** * Surfaceview initialization function/public Mysurfaceview {super (context);
    SFH = This.getholder ();Sfh.addcallback (this);
    Paint = new paint ();
    Paint.setcolor (Color.White);
    Paint.setantialias (TRUE);
  Setfocusable (TRUE); /** * Surfaceview View creation, response to this function/@Override public void surfacecreated (Surfaceholder holder) {screenw = t
    His.getwidth ();
    Screenh = This.getheight ();
    Flag = true;
    instance thread th = new thread (this);
  Start thread Th.start ();
      /** * Game drawing/public void Mydraw () {try {canvas = Sfh.lockcanvas ();
        if (canvas!= null) {Canvas.drawcolor (color.black);
        Paint.setcolor (Color.White);
        Paint.setstyle (Style.fill);
          if (iscollsion) {paint.settextsize (20); Canvas.drawtext ("collision!
        ", 0, paint);
        //Draw two rectangular canvas.drawrect (rectX1, rectY1, rectX1 + rectW1, rectY1 + rectH1, paint);
        Canvas.drawrect (rectX2, rectY2, rectX2 + rectW2, rectY2 + rectH2, paint); ---Draw the collision area using a paint.setstyle and set the brush color white (style.stroke);
        Paint.setcolor (color.red);  Draws all rectangular collision areas for the first rectangle for (int i = 0; i < arrayrect1.length i++) {canvas.drawrect (Arrayrect1[i].left + THIS.RECTX1, Arrayrect1[i].top + this.recty1, Arrayrect1[i].right + this.rectx1, Arrayrect1[i].bottom + thi
        S.recty1, paint); ///Draw all rectangular collision areas for the second rectangle for (int i = 0; i < arrayrect2.length i++) {canvas.drawrect (arrayRect2
              [I].left + this.rectx2, Arrayrect2[i].top + this.recty2, Arrayrect2[i].right + this.rectx2, ArrayRect2[i].bottom
        + rectY2, paint); (Exception e) {//Todo:handle Exception} finally {if (Canvas!= null) SF
    H.unlockcanvasandpost (canvas); /** * Touchscreen Event Monitor/@Override public boolean ontouchevent (Motionevent event) {//Let rectangle 1 move with touchscreen position Rectx
    1 = (int) event.getx ()-rectw1/2;
    rectY1 = (int) event.gety ()-recth1/2; if (Iscollsionwithrect (ArrayRect1, Arrayrect2)) {iscollsion = true;
    else {iscollsion = false;
  return true; /** * Button Event Monitor/@Override public boolean onKeyDown (int keycode, keyevent event) {return Super.onkeydow
  N (keycode, event);      }/** * Game logic/private void logic () {}//rect class four properties top bottom left right//respectively indicates the top and bottom of this rectangle
    Left and right public boolean iscollsionwithrect (rect[] Rectarray, rect[] rect2array) {Rect Rect = null;
    Rect rect2 = null;
      for (int i = 0; i < rectarray.length; i++) {//to sequentially remove each rectangular instance of the first rectangular array rect = rectarray[i];
      Gets the property value int x1 = rect.left + this.rectx1 for each rectangle element in the first rectangular array;
      int y1 = rect.top + this.recty1;
      int w1 = Rect.right-rect.left;
      int h1 = Rect.bottom-rect.top;
        for (int j = 0; J < Rect2array.length; J +) {//to sequentially remove each rectangular instance of the second rectangular array rect2 = rect2array[j];
        Gets the property value int x2 = rect2.left + this.rectx2 for each rectangle element in the second rectangular array; int y2 = Rect2.top + This.recty2;
        int w2 = Rect2.right-rect2.left;
        int h2 = Rect2.bottom-rect2.top; Loop through two rectangular collisions. The position relationship between all elements of an array if (x1 >= x2 && x1 >= x2 + w2) {} else if (x1 <= x2 &&am P x1 + W1 <= x2) {} else if (y1 >= y2 && y1 >= y2 + h2) {} else if (y1 <= y2 &&amp ;
        Y1 + h1 <= y2) {} else {//As long as there is a collision between a colliding rectangular array and another colliding rectangular array, the collision is considered to be true;
  }} return false;
      @Override public void Run () {while (flag) {Long start = System.currenttimemillis ();
      Mydraw ();
      Logic ();
      Long end = System.currenttimemillis ();
        try {if (End-start <) {Thread.Sleep (End-start));
      } catch (Interruptedexception e) {e.printstacktrace ();  /** * Surfaceview view state changed in response to this function */@Override public void surfacechanged (surfaceholder holder, int format, int Width, int height) {}/** * Surfaceview View dies, respond to this function */@Override public void surfacedestroyed (Surfaceholder hol
  Der) {flag = false;

 }
}

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