我在Android OpenGL中有一个精灵。这精灵(小beetlebug)总是在前进的方向前进,我用:基于旋转的雪碧运动
sprite.setPosition(posX, posY);
现在我有一个旋转的方法,当用户手势向左或向右的bug旋转:
private void applyRotation() {
for(int i=0;i<beetleBug.size;i++) {
Sprite s = beetleBug.get(i);
s.setOrigin(s.getWidth()/2, s.getHeight()/2);
s.setRotation(angle);
}
}
现在,当错误向前移动时,他总是会根据旋转角度计算新的x和y坐标,以便错误始终向前。有没有人有算法来计算旋转角度的方向?
这里是整个错误级:
public class Bug {
private SpriteBatch spriteBatch = null;
private TextureAtlas spriteSheet;
private Array<Sprite> beetleBug;
private int currentFrame = 0;
private final float frameLength = 0.10f; //in seconds, how long a frame last
private float animationElapsed = 0.0f;
private float angle = 0.0f;
private float posX = 0.0f;
private float posY = 0.0f;
private float sizeX = 100.0f;
private float sizeY = 100.0f;
private float offSet = 50.0f;
public Bug() {
spriteBatch = new SpriteBatch();
spriteSheet = new TextureAtlas("assets/data/bug.txt");
beetleBug = spriteSheet.createSprites("bug");
// dont forget to set the size of your sprites!
for(int i=0; i<beetleBug.size; i++){
beetleBug.get(i).setSize(sizeX, sizeY);
}
applyPosition();
}
public void handleInput() {
boolean leftKey = Gdx.input.isKeyPressed(Input.Keys.LEFT);
boolean rightKey = Gdx.input.isKeyPressed(Input.Keys.RIGHT);
if(rightKey) {
if(angle <= 0) {
angle = 360;
}
angle -= 2f;
applyRotation();
}
if(leftKey) {
if(angle >= 360) {
angle = 0;
}
angle += 2f;
applyRotation();
}
applyPosition();
}
private void applyPosition() {
float x = (float) Math.cos(angle);
float y = (float) Math.sin(angle);
posX = posX + x;
posY = posY + y;
for(int i=0; i<beetleBug.size; i++){
beetleBug.get(i).setPosition(posX - offSet, posY -offSet); // optional: center the sprite to screen
}
}
private void applyRotation() {
for(int i=0;i<beetleBug.size;i++) {
Sprite s = beetleBug.get(i);
s.setOrigin(s.getWidth()/2, s.getHeight()/2);
s.setRotation(angle);
}
}
public void render(OrthographicCamera cam) {
float dt = Gdx.graphics.getDeltaTime();
animationElapsed += dt;
while(animationElapsed > frameLength){
animationElapsed -= frameLength;
currentFrame = (currentFrame == beetleBug.size - 1) ? 0 : ++currentFrame;
}
spriteBatch.setProjectionMatrix(cam.combined);
spriteBatch.begin();
beetleBug.get(currentFrame).draw(spriteBatch);
spriteBatch.end();
}
}
请参阅上面的整个Bug类,它不以这种方式工作,beetlebug正在旋转,但每次按键输入后总是移动n个错误的方向。 – illvoid 2013-05-03 20:37:45
请注意,这将用于指向正y方向的零度,随着顺时针方向角度增加。例如指南针点 – Maple 2013-05-06 13:35:09