图片屏幕LibGdx--GearJoint齿轮关节

本文纯属个人见解，是对前面学习的总结，如有描述不正确的地方还请高手指正~

package com.joye3g.joint;



import com.badlogic.gdx.ApplicationListener;

import com.badlogic.gdx.Gdx;

import com.badlogic.gdx.graphics.GL10;

import com.badlogic.gdx.graphics.OrthographicCamera;

import com.badlogic.gdx.math.Vector2;

import com.badlogic.gdx.physics.box2d.Body;

import com.badlogic.gdx.physics.box2d.BodyDef;

import com.badlogic.gdx.physics.box2d.BodyDef.BodyType;

import com.badlogic.gdx.physics.box2d.Box2DDebugRenderer;

import com.badlogic.gdx.physics.box2d.CircleShape;

import com.badlogic.gdx.physics.box2d.EdgeShape;

import com.badlogic.gdx.physics.box2d.FixtureDef;

import com.badlogic.gdx.physics.box2d.World;

import com.badlogic.gdx.physics.box2d.joints.GearJointDef;

import com.badlogic.gdx.physics.box2d.joints.RevoluteJoint;

import com.badlogic.gdx.physics.box2d.joints.RevoluteJointDef;

import com.joye3g.joint.util.Transform;



public class GearJointDemo implements ApplicationListener{

	private Box2DDebugRenderer renderer;

	private OrthographicCamera camera;

	private static final float PXTM = 30;

	private World mWorld;

	@Override

	public void create() {

		float screenWidth = Gdx.graphics.getWidth();

		float screenHeight = Gdx.graphics.getHeight();

		renderer = new Box2DDebugRenderer();

		camera = new OrthographicCamera(screenWidth / PXTM, screenHeight / PXTM);

		mWorld = new World(new Vector2(0f, 0f), true);



		//绘制面地

		BodyDef bodyDef = new BodyDef();

		bodyDef.type = BodyType.StaticBody;

		bodyDef.position.set(-screenWidth / PXTM / 2, -screenHeight / PXTM / 2);

		Body mGroupBody = mWorld.createBody(bodyDef);

		EdgeShape edgeShape = new EdgeShape();

		edgeShape.set(new Vector2(0f, 1f), new Vector2(screenWidth / PXTM, 1f));

		FixtureDef fixtureDef = new FixtureDef();

		fixtureDef.shape = edgeShape;

		mGroupBody.createFixture(fixtureDef);



		//绘制一个半径为1米的圆形

		BodyDef mCircleBodyDef1 = new BodyDef();

		mCircleBodyDef1.type = BodyType.DynamicBody;

		//圆形的位置在屏幕(60,190)的位置

		Vector2 vector1 = Transform.ptm(60f, 190f, screenWidth, screenHeight, 0f, 0f, PXTM);

		mCircleBodyDef1.position.set(vector1);

		Body mCircle1 = mWorld.createBody(mCircleBodyDef1);

		CircleShape mCircleShape1 = new CircleShape();

		mCircleShape1.setRadius(1f);

		FixtureDef mCircleFix1 = new FixtureDef();

		mCircleFix1.shape = mCircleShape1;

		mCircleFix1.density = 3.0f;

		mCircle1.createFixture(mCircleFix1);



		//绘制一个半径为1米的圆形

		BodyDef mCircleBodyDef2 = new BodyDef();

		mCircleBodyDef2.type = BodyType.DynamicBody;

		//圆形的位置在屏幕(200,190)的位置

		Vector2 vector2 = Transform.ptm(200f, 190f, screenWidth, screenHeight, 0f, 0f, PXTM);

		mCircleBodyDef2.position.set(vector2);

		Body mCircle2 = mWorld.createBody(mCircleBodyDef2);

		CircleShape mCircleShape2 = new CircleShape();

		mCircleShape2.setRadius(1f);

		FixtureDef mCircleFix2 = new FixtureDef();

		mCircleFix2.shape = mCircleShape2;

		mCircleFix2.density = 3.0f;

		mCircle2.createFixture(mCircleFix2);



		//建创一个旋转节关

		RevoluteJointDef revoluteJointDef = new RevoluteJointDef();

		revoluteJointDef.initialize(mGroupBody, mCircle1, mCircle1.getWorldCenter());

		revoluteJointDef.maxMotorTorque = 20f;//马达的预期最大扭矩

		revoluteJointDef.motorSpeed = 50f;//马达的终究扭矩

		revoluteJointDef.enableMotor = true;//动启马达

		RevoluteJoint revoluteJoint1 = (RevoluteJoint) mWorld.createJoint(revoluteJointDef);



		//建创一个旋转节关

		RevoluteJointDef revoluteJointDef2 = new RevoluteJointDef();

		revoluteJointDef2.initialize(mGroupBody, mCircle2, mCircle2.getWorldCenter());

		RevoluteJoint revoluteJoint2 = (RevoluteJoint) mWorld.createJoint(revoluteJointDef2);

		

		//建创一个齿轮节关,mCircle1为驱动的Body,mCircle2为被驱动的Body

		GearJointDef gearJointDef = new GearJointDef();

		gearJointDef.bodyA = mCircle1;

		gearJointDef.bodyB = mCircle2;

		gearJointDef.joint1 = revoluteJoint1;

		gearJointDef.joint2 = revoluteJoint2;

		gearJointDef.ratio = 1f;

		mWorld.createJoint(gearJointDef);

	}



	@Override

	public void resize(int width, int height) {

	}



	@Override

	public void render() {

		GL10 gl=Gdx.graphics.getGL10();

		gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

		mWorld.step(Gdx.graphics.getDeltaTime(), 8, 6);

		renderer.render(mWorld, camera.combined);

	}



	@Override

	public void pause() {

	}



	@Override

	public void resume() {

	}



	@Override

	public void dispose() {

	}

}

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package com.joye3g.joint.util;



import com.badlogic.gdx.math.Vector2;



public class Transform {

	/**

	 * @param x_px				图片地点x标坐

	 * @param y_px				图片地点y标坐

	 * @param screenWidth		屏幕宽度

	 * @param screenHeight		屏幕度高

	 * @param width_px			图片宽度

	 * @param height_px			图片度高

	 * @param scale				缩放比例

	 * @return					（x,y）直接置设为body的position可以使body与图片重合

	 */

	public static Vector2 ptm(float x_px, float y_px, float screenWidth, float screenHeight, float width_px, float height_px, float scale){

		Vector2 vector2 = new Vector2();

		vector2.x = -(screenWidth - x_px * 2 - width_px) / scale / 2;

		vector2.y = -(screenHeight - y_px * 2 - height_px) / scale / 2;

		return vector2;

	}



	/**

	 * @param x_m				body地点x标坐

	 * @param y_m				body地点y标坐

	 * @param screenWidth		屏幕宽度

	 * @param screenHeight		屏幕度高

	 * @param wh				(x,y)body的宽高

	 * @param scale				缩放比例

	 * @return					（x,y）直接置设为图片的position可以使图片与body重合

	 */

	public static Vector2 mtp(float x_m, float y_m, float screenWidth, float screenHeight, Vector2 wh, float scale){

		Vector2 vector2 = new Vector2();

		vector2.x = x_m * scale + screenWidth / 2 - wh.x * scale;

		vector2.y = y_m * scale + screenHeight / 2 - wh.y * scale;

		return vector2;

	}

}

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