Android - 2D 平台碰撞检测 /w Gravity Physics

Question

由于这似乎是“堆栈”上反复出现的主题，因此我将强调我的问题，因为它没有涵盖。已经涵盖的是平台游戏等的 2D 瓷砖碰撞，但是根据我制作游戏的方式，没有瓷砖。我也没有使用额外的库，一切都是我自己写的。

我所拥有的是为游戏中的每个对象绑定 Rect。到目前为止，只有两个对象类在使用，Platform 和 Entity。 Entity 包含玩家移动等的所有东西，而 Platform 是一个坚固的非移动平台。

平台.java：

package com.toongames.game.objects;

import android.graphics.Color;
import android.graphics.Rect;

import com.toongames.framework.Graphics;

public class Platform {

    private int x, y;
    private int width, height;

    public Platform(int par1, int par2, int par3, int par4) {
        x = par1;
        y = par2;
        width = par3;
        height = par4;
    }

    public Rect getBounds() {
        return new Rect(x, y, x + width, y + height);
    }
}

Entity.java：

    package com.toongames.game.entity;

import android.graphics.Color;
import android.graphics.Point;
import android.graphics.Rect;

import com.toongames.framework.Graphics;
import com.toongames.framework.Image;

public class Entity {

    public final float GRAVITY = 0.1F;

    private String entityID;
    private Point pos;
    private int dx;
    private float vel;

    public Point desiredPos;
    public boolean onGround;

    public Entity(String par0String, int par1, int par2) {
        entityID = par0String;
        pos = new Point(par1, par2);

        desiredPos = pos;
        dx = 0;
        vel = 0;
    }

    public void update(float deltaTime) {
        vel = vel + (GRAVITY * deltaTime);

        pos.y += (vel * deltaTime);
        pos.x += dx;
    }

    public void setDx(int par1) {
        dx = par1;
    }

    public int getDx() {
        return dx;
    }

    public void setVelocity(int par1) {
        vel = par1;
    }

    public float getVelocity() {
        return vel;
    }

    public void setPos() {
        pos = desiredPos;
    }

    public Rect getBounds() {
        return new Rect(desiredPos.x, desiredPos.y, desiredPos.x + 80, desiredPos.y + 80);
    }
}

我已经成功地让玩家与上下两面的东西发生碰撞，但我终生无法让玩家左右碰撞。每当我向左或向右移动时与平台发生碰撞时，我都会跳到所碰撞的平台顶部。

我知道这与我的逻辑有关，但我无法弄清楚要使用的正确逻辑。

ScreenGame.java：

    package com.toongames.game.screen;

// Imports here...

public class ScreenGame extends Screen {

    private Entity player;

    private Button left, right, jump;

    private Platform floor, p, p2, p3;
    private ArrayList<Platform> platforms;

    public ScreenGame(Game game) {
        super(game);

        player = new Entity("PLAYER", 300, 100, Assets.charRight);

        left = new Button(Assets.move_left, 10, 790 - Assets.move_left.getHeight(), Assets.move_left.getWidth(), Assets.move_left.getHeight());
        right = new Button(Assets.move_right, 20 + Assets.move_left.getWidth(), 790 - Assets.move_right.getHeight(), Assets.move_right.getWidth(), Assets.move_right.getHeight());
        jump = new Button(Assets.jump, 1270 - Assets.jump.getWidth(), 790 - Assets.jump.getHeight(), Assets.jump.getWidth(), Assets.jump.getHeight());

        floor = new Platform(0, 790, 1280, 80);
        p = new Platform(1280 - 500, 500, 400, 80);
        p2 = new Platform(0, 200, 400, 80);
        p3 = new Platform(400, 120, 200, 80);
        platforms = new ArrayList<Platform>();
        platforms.add(floor);
        platforms.add(p);
        platforms.add(p2);
        platforms.add(p3);
    }

    // An update method calls these
    public void updateMovement(float deltaTime) {
        List<TouchEvent> touchEvents = game.getInput().getTouchEvents();

        int len = touchEvents.size();
        for (int i = 0; i < len; i++) {
            TouchEvent event = touchEvents.get(i);
            if (event.type == TouchEvent.TOUCH_DOWN) {
                if (inBounds(left.getBounds(), event)) {
                    player.setDx((int) -(deltaTime * 1.5F));
                } else if (inBounds(right.getBounds(), event)) {
                    player.setDx((int) deltaTime * 2);
                } else if (inBounds(jump.getBounds(), event)) {
                    if (player.onGround) {
                        player.setVelocity(-8);
                    }
                }
            } else if (event.type == TouchEvent.TOUCH_DRAGGED) {
                if (inBounds(left.getBounds(), event)) {
                    player.setDx((int) -deltaTime * 2);
                } else if (inBounds(right.getBounds(), event)) {
                    player.setDx((int) deltaTime * 2);
                } else if (inBounds(jump.getBounds(), event)) {
                    if (player.onGround) {
                        player.setVelocity(-8);
                    }
                } else {
                    player.setDx(0);
                    player.jumpCounter = 0;
                }
            } else if (event.type == TouchEvent.TOUCH_UP) {
                player.setDx(0);
                player.jumpCounter = 0;
            }
        }
    }

    // An update method calls these
    public void updateGameObjects(float deltaTime) {
        for (Platform p : platforms)
            p.update();

        player.update(deltaTime);
    }

    // An update method calls these
    public void checkCollisions() {
        Rect playerRect = player.getBounds();

        for (Platform p : platforms) {
            Rect pRect = p.getBounds();

            if (Rect.intersects(playerRect, pRect)) {
                Rect intersection = playerRect;
                intersection.intersect(pRect);

                if (player.getVelocity() != player.GRAVITY) {
                    int resolutionHeight;

                    if (player.getVelocity() < player.GRAVITY)
                        resolutionHeight = intersection.height();
                    else {
                        resolutionHeight = -intersection.height();
                        player.onGround = true;
                    }

                    player.setVelocity(0);

                    player.desiredPos = new Point(player.desiredPos.x, player.desiredPos.y + resolutionHeight);
                }
            }
        }

        player.setPos();
    }
}

作为一个额外的说明，我已经删除了一些与实体和实体健康等图像有关的不必要的代码。我还删除了一些空的方法和类似的东西，它们与以往没有任何关系。

[编辑] 删除大部分绘图代码和导入。现在所有绝对必要的东西都在那里了。

Answer 1

player.desiredPos = new Point(player.desiredPos.x, player.desiredPos.y + resolutionHeight);

这不是“上移，永不左右”吗？

我认为您的Rect.intersects 方法应该返回{ NONE, LEFT, RIGHT, UP, DOWN } 之一，指示碰撞发生的方向。所以你可以对碰撞做出正确的反应...