在libGDX中平稳跳转

Question

i want to create a jump of my player that is smooth it goes up then down its a 2D side scroller like Mario

iv'e tried wait and make jumps slow by using a lot of steps and i cant figure it out

player control class:

package com.mygdx.game;

import java.lang.Thread.State;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Input.Keys;
import com.badlogic.gdx.graphics.g2d.Sprite;
import com.badlogic.gdx.graphics.g2d.TextureRegion;
import com.badlogic.gdx.math.Vector2;


@SuppressWarnings("unused")
public class PlayerController {
    static int speed = 1;
    public static int jump = 0;

    static void keyInput() {
        jump++;
        if (Gdx.input.isKeyPressed(Keys.A)) {
            main.playerX += speed;
            main.backgroundSpriteX += speed;
        }
        if (Gdx.input.isKeyPressed(Keys.D)) {
            main.playerX -= speed;
            main.backgroundSpriteX -= speed;
        }
        if (Gdx.input.isKeyPressed(Keys.W)) {
             //this is where i want to be able to jump
        }
    }  
    static void Controller() {


        main.player = new Sprite(main.texture);
        main.playerX = (main.canvisWidth * 0);
        main.playerY = (main.canvisHeight * 0); //can be 0
    }
}

main class:

package com.mygdx.game;

import com.badlogic.gdx.ApplicationListener;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.Sprite;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;


public class main implements ApplicationListener {
    public static final int backgroundSpriteY = 0;
    public static final int backgroundSprite2Y = 0;
    public static int canvisWidth = 800;
    public static int canvisHeight = 480;
    public static int backgroundSpriteX = 0;
    public static Texture texture;
    public static int backgroundSprite2X = -canvisWidth;
    public static Sprite player;
    public static int playerX;
    public static int playerY;
    static SpriteBatch spriteBatch;
    static int Jumpframes = 0;
    private double playerSize = .4;

    public void create() {
        WorldObjects.shapeRender.setAutoShapeType(true);
        spriteBatch = new SpriteBatch();
        texture = new Texture(Gdx.files.internal("imageedit_3_3813241913.png"));
        PlayerController.Controller();
        WorldSetup.start();
        player.setSize((float) (player.getWidth() * playerSize), (float) (player.getHeight() * playerSize));
    }

    public void render() {
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
        PlayerController.keyInput();
        WorldController.Scroll();
        spriteBatch.begin();
        spriteBatch.draw(WorldSetup.backgroundTexture, backgroundSpriteX, backgroundSpriteY);
        spriteBatch.draw(WorldSetup.backgroundTexture2, backgroundSprite2X, backgroundSprite2Y);
        spriteBatch.draw(texture, playerX, playerY, player.getWidth(), player.getHeight());
        spriteBatch.end();
        WorldSetup.WorldRender();
        //Jumpframes++;
    }


    public void resize(int width, int height) {
    }

    public void pause() {
    }

    public void resume() {
    }

    public void dispose() {
    }

}

i want to have a slow jump like a Mario sort of jump and i cant seem to create a slow/smooth jump

I'd like 20 frame jump going up 30 pixels starting fast and slowing down

Answer 1

You can maybe get away from recording the start jump position like this... instead of using the buttons to directly alter their position, use the buttons to alter their velocity then use their current position plus xvelocity and yvelocity to calculate next position. when they press jump they get a increased y and every frame you reduce that until they land on a platform then set it back to 0.

Answer 2

I think what you need is a 2D Physics Engine for Games, The the popular one is Box2D

lots of tutorials on this, like Brent Aureli's works , to jump your character you just apply force on it like

player.b2body.applyForceToCenter(0, 80f, true);

hope this helps