我正在尝试使用libgdx wiki作为示例的基础来绘制精灵:https://github.com/libgdx/libgdx/wiki/Spritebatch%2C-Textureregions%2C-and-Sprites 但是我得到了这个错误:
Exception in thread "LWJGL Application" java.lang.NullPointerException
at com.MKgames.OptionScreen.render(OptionScreen.java:44)
at com.badlogic.gdx.Game.render(Game.java:46)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:206)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:114)
为2d游戏绘制精灵的最佳方法是什么,最佳做法是什么?
这是我的选项屏幕类,包括渲染方法:
package com.MKgames;
import sun.java2d.loops.DrawGlyphListAA.General;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Input.Keys;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
public class OptionScreen implements Screen{
com.MKgames.Game1 game;
OrthographicCamera camera;
SpriteBatch batch;
int farmerX;
public OptionScreen(com.MKgames.Game1 game1){
this.game = game;
camera = new OrthographicCamera();
camera.setToOrtho(true, 1920, 1080);
batch = new SpriteBatch();
farmerX = 960-85;
}
public void render(float delta) {
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
camera.update();
generalUpdate();
batch.setProjectionMatrix(camera.combined);
batch.begin();
FarmerAsset.farmer1.draw(batch);
batch.end();
}
public void generalUpdate() {
if(Gdx.input.isKeyPressed(Keys.A)||Gdx.input.isKeyPressed(Keys.LEFT)){
farmerX -= 5;
}
else if(Gdx.input.isKeyPressed(Keys.D)||Gdx.input.isKeyPressed(Keys.RIGHT)){
farmerX += 5;
}
}
@Override
public void show() {
}
@Override
public void pause() {
}
@Override
public void resume() {
}
@Override
public void dispose() {
}
@Override
public void resize(int width, int height) {
}
@Override
public void hide() {
}
}
还有一个班级农民为了抓住农夫精灵而烦恼: 包com.MKgames;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.Sprite;
public class FarmerAsset {
public static Texture texture_sheet;
public static Sprite farmer1;
public static Sprite farmer2;
public static Sprite farmer3;
public static Sprite farmer4;
public static Sprite farmer5;
public static Sprite farmer6;
public static Sprite farmer7;
public static Sprite farmer8;
public static void load(){
texture_sheet = new Texture(Gdx.files.internal("farmerSprite.png"));
farmer1 = new Sprite (texture_sheet, 0, 0, 170, 170);
farmer2 = new Sprite (texture_sheet, 170, 0, 170, 170);
farmer3 = new Sprite (texture_sheet, 340, 0, 170, 170);
farmer4 = new Sprite (texture_sheet, 680, 0, 170, 170);
farmer5 = new Sprite (texture_sheet, 0, 170, 170, 170);
farmer6 = new Sprite (texture_sheet, 170, 170, 170, 170);
farmer7= new Sprite (texture_sheet, 340, 170, 170, 170);
farmer8= new Sprite (texture_sheet, 680, 170, 170, 170);
farmer1.flip(false, true);
farmer2.flip(false, true);
farmer3.flip(false, true);
farmer4.flip(false, true);
farmer5.flip(false, true);
farmer6.flip(false, true);
farmer7.flip(false, true);
farmer8.flip(false, true);
}
}
答案 0 :(得分:1)
你得到一个NPE,因为在尝试渲染之前你没有实例化你的精灵。在屏幕的init()方法中(我猜你有一个,因为渲染(浮动)在其中并且你正在使用它),请调用FarmerAsset.load();
。这将加载你的纹理就像你问的那样。
[编辑]查看崩溃日志后,我发现您可能正在使用游戏而不是屏幕。不要感到困惑,它与Game implements Screen完全相同。
public OptionScreen(com.MKgames.Game1 game1){
this.game = game;
camera = new OrthographicCamera();
camera.setToOrtho(true, 1920, 1080);
batch = new SpriteBatch();
farmerX = 960-85;
//This is what's missing
FarmerAsset.load();
}