Android - 二維平臺碰撞檢測/ w重力物理

Question

由於這似乎是'堆棧'上反覆出現的話題，我將強化我的問題，因爲沒有涉及到。已經涵蓋的是用於平臺遊戲等的2D瓦片碰撞，但是以我製作遊戲的方式，沒有瓦片。我也沒有使用額外的庫，所有內容都是由我自己親自編寫的。

我擁有的是Rect's遊戲中的每一個物體。到目前爲止，只有兩個對象類正在使用，Platform和Entity。實體包含了玩家移動等所有的東西，而平臺是一個堅實的非移動平臺。

Platform.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); 
    } 
} 

我已經成功地取得了球員碰撞的東西都漲有跌，但我不能爲我的生活設法使玩家左右碰撞。每當我向左或向右移動時碰到平臺，我就跳到我碰撞的平臺的頂部。

我知道它與我的邏輯有關，但我無法弄清楚使用的正確邏輯。

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(); 
    } 
} 

作爲一個額外的說明，我已經削減了一些不必要的代碼與實體和實體健康等圖像做..我再切出空的方法和像這樣的東西，沒有什麼相關的東西。

[編輯]刪除大部分的圖紙代碼和導入。現在所有絕對必要的東西都在那裏。

Answer 1

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

是不是這個「上面移動，從來沒有右/左？」

我認爲你的Rect.intersects方法應該返回{ NONE, LEFT, RIGHT, UP, DOWN }之一，表明碰撞發生在哪個方向。所以你可以在正確的方向對碰撞作出反應...