Question

我正在寻找每次触摸屏幕或点击鼠标或每次用户输入时创建新对象。我有一些想法就像克隆，创建新的或添加ArrayList。类似的东西：

if (Gdx.input.JustTouched){ shapeRenderer.circle(Gdx.input.getX(),Gdx.input.getY(),10); }

但每次触摸时，都会画一个新的圆圈。我尝试过：

private Object[] appendValue(Object[] obj, Object newObj) {

    ArrayList<Object> temp = new ArrayList<Object>(Arrays.asList(obj));
    temp.add(newObj);
    return temp.toArray();

但是我不能将void方法（shapeRenderer.circle）分配给一个对象，所以不适合我。另一种方式是在if之外进行绘制，传递坐标，但保持在渲染循环中然后丢失坐标。是否有可能克隆方法并获得新的抽奖？如果有人回答，请告诉我，我会删除这个问题，我真的失去了

Answer 1

方法shapeRenderer.circle(float x, float y, float radius)在画布上绘制一个圆圈。它不会创建一个对象，它会在画布上创建一堆像素，一旦重绘画布就会丢失这些像素。

您需要存储要传递到circle方法的数据，以便您可以重绘旧圈子，并在触摸事件上添加更多内容。这样做的好方法是定义一个类Circle：

public class Circle {
    public float x;
    public float y;
    public float radius;

    public Circle(float x, float y, float radius) {
        this.x = x;
        this.y = y;
        this.radius = radius;
    }
}

然后您可以创建这些圈子的列表，并在每次检测到触摸事件时添加一个新圈子：

if (Gdx.input.JustTouched)
    circles.add(new Circle(Gdx.input.getX(),Gdx.input.getY(),10));

无论何时需要重新绘制屏幕，都要绘制所有圈子：

for (Circle circle : circles)
    shapeRenderer.circle(circle.x, circle.y, circle.radius);

修改

您的代码崩溃，因为您的圈子集合为空，并且您致电circles.add。除非你正确地实例化circles，否则这将引发空指针异常。

public class MyGdxGame implements ApplicationListener { ShapeRenderer shapeRenderer; OrthographicCamera camera; // It's a collection specifically of Circles. Also, there's one per game, so don't make it static. Collection<Circle> circles; @Override public void create() { camera = new OrthographicCamera(); configureCamera(); shapeRenderer = new ShapeRenderer(); // Make it an empty collection to begin with circles = new ArrayList<Circle>(); } @Override public void render() { Gdx.gl.glClearColor(1, 1, 1, 1); Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT); camera.update(); shapeRenderer.setProjectionMatrix(camera.combined); shapeRenderer.begin(ShapeRenderer.ShapeType.Filled); shapeRenderer.setColor(0, 0.5f, 0, 1); shapeRenderer.circle(50, 50, 40); shapeRenderer.setColor(0.5f, 0, 0, 1); shapeRenderer.rect(10, 100, 80, 80); shapeRenderer.setColor(0, 0, 0.5f, 1); shapeRenderer.triangle(10, 200, 90, 200, 50, 270); // Check for input, and add the new circle, *before* drawing all the circles if (Gdx.input.justTouched()) circles.add(new Circle(Gdx.input.getX(),Gdx.input.getY(),10)); for (Circle circle : circles) shapeRenderer.circle(circle.x, circle.y, circle.radius); shapeRenderer.end(); } // *static* - Google the difference between inner vs nested classes public static class Circle { public float x; public float y; public float radius; public Circle(float x, float y, float radius) { this.x = x; this.y = y; this.radius = radius; } } }

Answer 2

想想我会在这里做：

public class MyGdxGame implements ApplicationListener
{
ShapeRenderer shapeRenderer;
OrthographicCamera camera;
static Collection circles;

@Override
public void create()
{       
camera = new OrthographicCamera();
configureCamera();
circles = null;

shapeRenderer = new ShapeRenderer();
}

@Override
public void render()
{       
    Gdx.gl.glClearColor(1, 1, 1, 1);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

camera.update();
shapeRenderer.setProjectionMatrix(camera.combined);
shapeRenderer.begin(ShapeRenderer.ShapeType.Filled);

shapeRenderer.setColor(0, 0.5f, 0, 1);
shapeRenderer.circle(50, 50, 40);

shapeRenderer.setColor(0.5f, 0, 0, 1);
shapeRenderer.rect(10, 100, 80, 80);

shapeRenderer.setColor(0, 0, 0.5f, 1);
shapeRenderer.triangle(10, 200, 90, 200, 50, 270);


for (Circle circle : circles)
shapeRenderer.circle(circle.x, circle.y, circle.radius);

if (Gdx.input.justTouched())
    circles.add(new Circle(Gdx.input.getX(),Gdx.input.getY(),10));

shapeRenderer.end();
}


public class Circle {
   public float x;
   public float y;
   public float radius;

public Circle(float x, float y, float radius) {
    this.x = x;
    this.y = y;
    this.radius = radius;
}
}
}

在render（）方法上渲染新对象类型？

2 个答案: