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() {
}
}
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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