add simple body test render by canvas

huzongyao · May 18, 2018 · 492a302 · 492a302
1 parent 9164fc3
commit 492a302
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Showing 8 changed files with 265 additions and 4 deletions.
diff --git a/README.md b/README.md
@@ -10,13 +10,15 @@ To Learn JBox2D and try to create some 2D physics engine based effects for Andro
  }
  ```
  * Learn JBox2D With Testbed Cases
+ * JBox2D may not so efficient as Box2D C++ Version
  * For More Information: https://github.com/jbox2d/jbox2d
+ * Box2D C++: https://github.com/erincatto/Box2D
 
 
 #### screenshot
-| TestBed        	| MobikeTag           | TestBed  	|
+| Simple Body   | MobikeTag     | TestBed  	|
 | ------------- |:-------------:| ---------:|
-| ![image](https://raw.githubusercontent.com/huzongyao/JBox2DEffects/master/misc/testbed.gif)| ![image](https://raw.githubusercontent.com/huzongyao/JBox2DEffects/master/misc/mobike_tag.gif)| ![image](https://raw.githubusercontent.com/huzongyao/JBox2DEffects/master/misc/testbed.gif) |
+| ![image](https://raw.githubusercontent.com/huzongyao/JBox2DEffects/master/misc/simple_body.gif)| ![image](https://raw.githubusercontent.com/huzongyao/JBox2DEffects/master/misc/mobike_tag.gif)| ![image](https://raw.githubusercontent.com/huzongyao/JBox2DEffects/master/misc/testbed.gif) |
 
 
 ### About Me

diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
@@ -21,6 +21,9 @@
         <activity
             android:name=".activity.EndlessBallActivity"
             android:label="Endless Ball" />
+        <activity
+            android:name=".activity.SimpleBodyActivity"
+            android:label="Simple Ball" />
     </application>
 
 </manifest>
diff --git a/app/src/main/java/com/hzy/jbox2d/effects/activity/MainActivity.java b/app/src/main/java/com/hzy/jbox2d/effects/activity/MainActivity.java
@@ -18,7 +18,12 @@ protected void onCreate(Bundle savedInstanceState) {
         ButterKnife.bind(this);
     }
 
-    @OnClick(R.id.button_simple_ball)
+    @OnClick(R.id.button_simple_body)
+    public void onMButtonSimpleClicked() {
+        startActivity(new Intent(this, SimpleBodyActivity.class));
+    }
+
+    @OnClick(R.id.button_endless_ball)
     public void onMButtonSimpleBallClicked() {
         startActivity(new Intent(this, EndlessBallActivity.class));
     }

diff --git a/app/src/main/java/com/hzy/jbox2d/effects/activity/SimpleBodyActivity.java b/app/src/main/java/com/hzy/jbox2d/effects/activity/SimpleBodyActivity.java
@@ -0,0 +1,14 @@
+package com.hzy.jbox2d.effects.activity;
+
+import android.os.Bundle;
+
+import com.hzy.jbox2d.effects.R;
+
+public class SimpleBodyActivity extends BaseActivity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_simple_body);
+    }
+}
diff --git a/app/src/main/java/com/hzy/jbox2d/effects/view/SimpleBodyView.java b/app/src/main/java/com/hzy/jbox2d/effects/view/SimpleBodyView.java
@@ -0,0 +1,218 @@
+package com.hzy.jbox2d.effects.view;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.support.annotation.Nullable;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+
+import org.jbox2d.collision.shapes.CircleShape;
+import org.jbox2d.collision.shapes.EdgeShape;
+import org.jbox2d.collision.shapes.PolygonShape;
+import org.jbox2d.common.Vec2;
+import org.jbox2d.dynamics.Body;
+import org.jbox2d.dynamics.BodyDef;
+import org.jbox2d.dynamics.BodyType;
+import org.jbox2d.dynamics.FixtureDef;
+import org.jbox2d.dynamics.World;
+
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * Created by huzongyao on 2018/5/14.
+ */
+
+public class SimpleBodyView extends View {
+
+    private Paint mPaint;
+    // assume the world width is 8m
+    private float mWorldWidth = 8f;
+    //pixels in per meter
+    private float mDpm;
+    private float mWorldHeight;
+    private World mWorld;
+    private float mBallRadius = 0.20f;
+    private int mColorFill;
+    private int mColorStroke;
+    private List<Body> mBallList;
+    private List<Body> mCubeList;
+
+    public SimpleBodyView(Context context) {
+        this(context, null);
+    }
+
+    public SimpleBodyView(Context context, @Nullable AttributeSet attrs) {
+        this(context, null, 0);
+    }
+
+    public SimpleBodyView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        init();
+    }
+
+    private void init() {
+        mPaint = new Paint();
+        mPaint.setAntiAlias(true);
+        mColorFill = Color.parseColor("#44ff4488");
+        mColorStroke = Color.parseColor("#ff994488");
+        mBallList = new LinkedList<>();
+        mCubeList = new LinkedList<>();
+    }
+
+    @Override
+    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
+        super.onSizeChanged(w, h, oldw, oldh);
+        mDpm = w / mWorldWidth;
+        mWorldHeight = h / mDpm;
+    }
+
+    @Override
+    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
+        super.onLayout(changed, left, top, right, bottom);
+        createNewWorld();
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        if (event.getAction() == MotionEvent.ACTION_DOWN) {
+            createMixBodies();
+        }
+        return super.onTouchEvent(event);
+    }
+
+    private float getScreenRotate(float radians) {
+        return (float) (radians * 180f / Math.PI);
+    }
+
+    /**
+     * create the world
+     */
+    private void createNewWorld() {
+        mWorld = new World(new Vec2(0f, 9.8f));
+        createBorder();
+        createMixBodies();
+    }
+
+    private void createMixBodies() {
+        for (int i = 0; i < 8; i++) {
+            mBallList.add(createBallBody(i));
+            mCubeList.add(createCubeBody(i));
+        }
+    }
+
+    /**
+     * create the moving ball
+     */
+    private Body createBallBody(int index) {
+        BodyDef bodyDef = new BodyDef();
+        bodyDef.type = BodyType.DYNAMIC;
+        // set original position
+        bodyDef.position.set(mWorldWidth / 2 + 0.1f, 0.1f * index);
+        CircleShape shape = new CircleShape();
+        shape.setRadius(mBallRadius);
+        FixtureDef fixture = new FixtureDef();
+        fixture.shape = shape;
+        // so the body will move forever
+        fixture.friction = 0.1f;
+        fixture.restitution = 0.7f;
+        fixture.density = 0.3f;
+        Body body = mWorld.createBody(bodyDef);
+        body.createFixture(fixture);
+        return body;
+    }
+
+    private Body createCubeBody(int index) {
+        BodyDef bodyDef = new BodyDef();
+        bodyDef.type = BodyType.DYNAMIC;
+        // set original position
+        bodyDef.position.set(mWorldWidth / 2 + 0.1f * index, 0.1f);
+        PolygonShape shape = new PolygonShape();
+        shape.setAsBox(mBallRadius, mBallRadius);
+        FixtureDef fixture = new FixtureDef();
+        fixture.shape = shape;
+        // so the body will move forever
+        fixture.friction = 0.2f;
+        fixture.restitution = 0.5f;
+        fixture.density = 0.6f;
+        Body body = mWorld.createBody(bodyDef);
+        body.createFixture(fixture);
+        body.applyForceToCenter(new Vec2(0.1f, 0.3f));
+        return body;
+    }
+
+    /**
+     * create the borders for the world
+     */
+    private void createBorder() {
+        BodyDef bodyDef = new BodyDef();
+        Body groundBody = mWorld.createBody(bodyDef);
+        EdgeShape edge = new EdgeShape();
+        FixtureDef boxShapeDef = new FixtureDef();
+        boxShapeDef.shape = edge;
+        // top
+        edge.set(new Vec2(0f, 0f), new Vec2(mWorldWidth, 0f));
+        groundBody.createFixture(boxShapeDef);
+        // left
+        edge.set(new Vec2(0f, 0f), new Vec2(0f, mWorldHeight));
+        groundBody.createFixture(boxShapeDef);
+        // right
+        edge.set(new Vec2(mWorldWidth, 0f), new Vec2(mWorldWidth, mWorldHeight));
+        groundBody.createFixture(boxShapeDef);
+        // bottom
+        edge.set(new Vec2(0f, mWorldHeight), new Vec2(mWorldWidth, mWorldHeight));
+        groundBody.createFixture(boxShapeDef);
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        mWorld.step(1f / 60, 8, 12);
+        // draw background
+        canvas.drawColor(Color.parseColor("#cccccc"));
+        for (Body body : mBallList) {
+            drawBallBody(canvas, body);
+        }
+        for (Body body : mCubeList) {
+            drawCubeBody(canvas, body);
+        }
+        invalidate();
+    }
+
+    private void drawCubeBody(Canvas canvas, Body body) {
+        canvas.save();
+        canvas.translate(body.getPosition().x * mDpm, body.getPosition().y * mDpm);
+        canvas.scale(mBallRadius * mDpm, mBallRadius * mDpm);
+        canvas.rotate(getScreenRotate(body.getAngle()));
+
+        mPaint.setStyle(Paint.Style.FILL);
+        mPaint.setColor(mColorFill);
+        canvas.drawRect(-1f, -1f, 1f, 1f, mPaint);
+
+        mPaint.setStyle(Paint.Style.STROKE);
+        mPaint.setColor(mColorStroke);
+        canvas.drawRect(-1f, -1f, 1f, 1f, mPaint);
+
+        canvas.restore();
+    }
+
+    private void drawBallBody(Canvas canvas, Body body) {
+        canvas.save();
+        canvas.translate(body.getPosition().x * mDpm, body.getPosition().y * mDpm);
+        canvas.scale(mBallRadius * mDpm, mBallRadius * mDpm);
+        canvas.rotate(getScreenRotate(body.getAngle()));
+
+        mPaint.setStyle(Paint.Style.FILL);
+        mPaint.setColor(mColorFill);
+        canvas.drawCircle(0f, 0f, 1f, mPaint);
+
+        mPaint.setStyle(Paint.Style.STROKE);
+        mPaint.setColor(mColorStroke);
+        canvas.drawCircle(0f, 0f, 1f, mPaint);
+        canvas.drawLine(0f, 0f, 1f, 0f, mPaint);
+
+        canvas.restore();
+    }
+}
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
@@ -11,7 +11,14 @@
         android:orientation="vertical">
 
         <Button
-            android:id="@+id/button_simple_ball"
+            android:id="@+id/button_simple_body"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="8dp"
+            android:text="Simple Body View" />
+
+        <Button
+            android:id="@+id/button_endless_ball"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:layout_marginTop="8dp"

diff --git a/app/src/main/res/layout/activity_simple_body.xml b/app/src/main/res/layout/activity_simple_body.xml
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context="com.hzy.jbox2d.effects.activity.SimpleBodyActivity">
+
+    <com.hzy.jbox2d.effects.view.SimpleBodyView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+
+</FrameLayout>
diff --git a/misc/simple_body.gif b/misc/simple_body.gif