Sprite animation Libgdx Java

Question

Trying to have a 2-d, top down sprite that rotates and is animated, i have the main class where it is rendered, and a separate 'assets' class where it is created. The rotation works, however the sprite stays on the same frame. I used the libgdx wiki to try and animate my sprite https://github.com/libgdx/libgdx/wiki/2D-Animation

Here is the code in the assets class:

public class Asset implements ApplicationListener, Screen{

    public static Texture walkSheet;




    private static final int    FRAME_COLS = 4;     
    private static final int    FRAME_ROWS = 2;     

    static Animation           walkAnimation;      
    static TextureRegion[]         walkFrames;     
    static TextureRegion           currentFrame;      
    static SpriteBatch spriteBatch;

    static float stateTime;                


    public static void load(){
        walkSheet = new Texture(Gdx.files.internal(".png"));


        TextureRegion[][] tmp = TextureRegion.split(walkSheet, walkSheet.getWidth()/FRAME_COLS, walkSheet.getHeight()/FRAME_ROWS);              // #10
        walkFrames = new TextureRegion[FRAME_COLS * FRAME_ROWS];
        int index = 0;
        for (int i = 0; i < FRAME_ROWS; i++) {
            for (int j = 0; j < FRAME_COLS; j++) {
                walkFrames[index++] = tmp[i][j];
            }
        }
        walkAnimation = new Animation(0.1f, walkFrames);      // #11
        spriteBatch = new SpriteBatch();                // #12
        stateTime = 0f;
        stateTime += Gdx.graphics.getDeltaTime();
        currentFrame = walkAnimation.getKeyFrame(stateTime, true);
    }

And here is how it is rendered:

game.batch.draw(Asset.currentFrame, x, y, (float)85, (float)85, (float)170, (float)170, (float)1, (float)1, (float)angleDegrees + 270);

What do i need to do to correctly animate the sprite?

Answer 1

The frame will never animate because you are not updating it. In the load() method you did the following:

stateTime += Gdx.graphics.getDeltaTime();
currentFrame = walkAnimation.getKeyFrame(stateTime, true);  

but this will get executed only once when you call the load() method.

As your Asset class implements the Screen interface you must have implemented the abstract method render(float delta), so you need to update the frame in that method as follows:

 public void render(float delta)
 {
   stateTime += delta;
   currentFrame = walkAnimation.getKeyFrame(stateTime, true);  
   // Then render the frame as follows
   batch.draw(currentFrame, x, y, (float)85, (float)85, (float)170, (float)170, (float)1, (float)1, (float)angleDegrees + 270);
 }