LibGDX 1.5围绕其中心旋转精灵

Question

I am trying to rotate a sprite around its center, but no matter what I try, I always get it rotating around a corner. I create the sprite in this way:

Pixmap pixmap = new Pixmap(64, 64, Format.RGBA8888);
pixmap.setColor(153/255f, 255/255f, 153/255f, 255/255f);
pixmap.fillTriangle(0, 0, 0, 32, 32, 16);
Texture texture = new Texture(pixmap);
triangle = new Sprite(texture);
triangle.setSize(3, 3);
triangle.setOriginCenter();
triangle.setPosition(0 - triangle.getWidth() / 2.0f, 0 - triangle.getHeight() / 2.0f);

then I rotate it every deltaTime in this way:

triangle.rotate(90 * deltaTime);

and render it like this:

batch.begin();
worldController.triangle.draw(batch);
batch.end();

I am following the example in the book "Learning LibGDX Game Development, Second edition", so I have a WorldController and a WorldRenderer. What am I missing? Shouldn't it be enough to set the sprite origin to its center and draw it? This is the behaviour I am having:

while I would like it to rotate "in place".

Answer 1

It seems that you have missed the line

triangle.setOrigin(originX, originY);

(originX, originY) being the center coordinates of your triangle.

EDIT: The reason why your current code doesn't work is because the current center origin is (0, 0).

(I am not sure why but it appeared to be the center when I tested your code). You can add logs to your code through using

Gdx.app.log("Tag", "LogInformation");

Here is what you should do

originX = (0+32)/2;
originY = (0+32)/2;

or

originX = (lowestXValue+highestXValue)/2;
originY = (lowestYValue+heightYValue)/2;

Here is the API on Sprite, it could help you more on rotate()

Answer 2

Ok, I found the problem. At first I declared the pixmap with a 32x32 size and filled the triangle accordingly. Then I was messing around with it and changed the size to 64x64, but the triangle was drawn by using the old coordinates, thus occupying the bottom left "subsquare" of the whole pixmap, that's why it was rotating in that way.