Question

首先，让我说我刚刚开始探索Box2D和LibGDX的世界。所以，如果我正在做什么/问什么是非常新秀...好吧 - 现在你知道为什么了！

我正在尝试创建一个Box2d World，它具有落在地面上的坠落体（动态）（静态）

世界的重力为-9.8f。
地面有0.0f摩擦
落体具有0.0f的角速度，角阻尼和线性阻尼。
下落体的起始线速度为20.0f / L.

我注意到的奇怪的“问题”是当身体坠落时，它会失去线速度。

玩家的起点越高 - 他到达地面时的线速度越低。

这是我正在使用的代码。

import com.badlogic.gdx.ApplicationListener;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Input.Keys;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.Texture;
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.FixtureDef;
import com.badlogic.gdx.physics.box2d.PolygonShape;
import com.badlogic.gdx.physics.box2d.World;

public class TestGame implements ApplicationListener {
    private OrthographicCamera camera;
    private int GAME_WIDTH = 1024 ;
    private int GAME_HEIGHT = 768 ;


    Box2DDebugRenderer renderer;
    World world ;

    BodyDef bdefPlayer;
    FixtureDef fdefPlayer;
    PolygonShape shapePlayer;
    Body fallingObject;
    int fallingObjectHeight = 64;
    int fallingObjectWidth = 64;

    BodyDef bdefGround;
    FixtureDef fdefGround;
    PolygonShape shapeGround;
    int numberOfGroundUnitsToCreate = 100;
    int groundUnitHeight = 64;
    int groundUnitWidth = 64;
    Body groundUnitsList[] = new Body[numberOfGroundUnitsToCreate];

    boolean isDebugMode = true;

    @Override
    public void create() {
        Texture.setEnforcePotImages(false);

        // Create World
        world = new World(new Vector2(0.0f, -9.8f), false);

        // Create debug render
        renderer = new Box2DDebugRenderer();

        // Initiate camera
        camera = new OrthographicCamera(GAME_WIDTH, GAME_HEIGHT);
        camera.setToOrtho(false);
        camera.position.set(GAME_WIDTH/2, GAME_HEIGHT/2, 0);

        // Create Player
        createPlayer();

        // Create Ground
        createGround();

    }

    public void render() {              
        Gdx.gl.glClearColor(0, 0, 0, 0);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        // Setup camera to follow Player
        camera.position.x = fallingObject.getPosition().x + 50; 
        camera.update();    

        // Update and render the world
        world.step(1/12f, 6, 2);
        if(isDebugMode) {
            renderer.render(world, camera.combined);            
        }

        System.out.println(
                            "Linear Velocity: " + fallingObject.getLinearVelocity() +
                            " Linear Damping: " + fallingObject.getLinearDamping() +
                            " Angular Velocity: " + fallingObject.getAngularVelocity() +
                            " Angular Damping: " + fallingObject.getAngularDamping() +
                            " World Gravity: " + world.getGravity() +
                            " Density: " + fallingObject.getMass() 
                          );

        handleInput();
    }

    private void createPlayer() { 
        bdefPlayer = new BodyDef();
        fdefPlayer = new FixtureDef();
        shapePlayer = new PolygonShape();

        // create player
        bdefPlayer.type = BodyType.DynamicBody;
        bdefPlayer.linearVelocity.x = 20.0f;
        bdefPlayer.linearDamping = 0.00f;
        bdefPlayer.angularDamping = 0.0f;
        bdefPlayer.angularVelocity = 0.0f;
        bdefPlayer.position.set(50,  250);
        fallingObject = world.createBody(bdefPlayer);

        shapePlayer.setAsBox(fallingObjectHeight/2 , fallingObjectWidth/2);
        fdefPlayer.shape = shapePlayer;
        fallingObject.createFixture(fdefPlayer);

        // create foot sensor
        shapePlayer.setAsBox(fallingObjectWidth/2 , 10); 
        fdefPlayer.shape = shapePlayer;
        fdefPlayer.isSensor = true;
        fallingObject.createFixture(fdefPlayer);
    }

    private void createGround() {
        bdefGround = new BodyDef();
        fdefGround = new FixtureDef();
        shapeGround = new PolygonShape();

        for (int i=0; i<numberOfGroundUnitsToCreate; i++) {
            bdefGround.type = BodyType.StaticBody;
            bdefGround.position.set((float) ((groundUnitWidth + 0.5) *i )  , 0);
            shapeGround.setAsBox(groundUnitWidth/2 , groundUnitHeight/2);
            fdefGround.shape = shapeGround;
            fdefGround.friction = 0.0f;
            Body grassTileBodyTemp = world.createBody(bdefGround);
            grassTileBodyTemp.createFixture(fdefGround);

            groundUnitsList[i]= grassTileBodyTemp;
        }
    }

    public void handleInput() {
        if(Gdx.input.isKeyPressed(Keys.SPACE)) 
            fallingObject.applyForceToCenter(0, 20.0f, true);

        if(Gdx.input.isKeyPressed(Keys.RIGHT)) 
            fallingObject.applyForceToCenter(20.0f, 0, true);
    }

    @Override
    public void dispose() {
        // TODO Auto-generated method stub

    }

    @Override
    public void pause() {
        // TODO Auto-generated method stub

    }

    @Override
    public void resize(int arg0, int arg1) {
        // TODO Auto-generated method stub

    }

    @Override
    public void resume() {
        // TODO Auto-generated method stub

    }
}

对于我可能导致此问题的错误而言，我最终会陷入困境。

Libgdx Box2D - 身体跌倒时线性速度下降

0 个答案: