为什么libgdx SpriteBatch / BitmapFont会破坏Texture.bind？

Question

I'm writing a game for Android using libgdx. Here is some code that draws a textured torus:

Gdx.gl10.glPushMatrix();
Gdx.gl10.glTranslatef(center.x, center.y, 0);
Gdx.gl10.glRotatef(0, 0, 1, angle * 360f / (2f * (float)Math.PI));
texture.bind();
mesh.render(GL10.GL_TRIANGLE_STRIP);
Gdx.gl10.glPopMatrix();

...and here is some code that draws a bit of text:

spriteBatch.begin();
spriteBatch.setColor(1, 1, 1, 1);
float fps = 1f / Gdx.graphics.getDeltaTime();
font.draw(spriteBatch, "fps: " + fps, 0, 50);
spriteBatch.end();

The first bit of code works, frame after frame, until the second bit of code runs. After that, the first bit's triangle strip is rendered using only the latest glMaterial. Any idea why this is happening?

Update: Solved! It turns out SpriteBatch.end() calls glDisable(GL_TEXTURE_2D). Just had to read the source...

Answer 1

It actually says so in the Javadocs as well. Rule of thumb: all libgdx classes connected to OpenGL ES will change the minimum amount of states and most likely won't reset things as querying GL for state is costly.

Answer 2

我遇到了同样的问题，我的解决方案是将活动纹理设置回GL_TEXTURE0，然后让SpriteBatch（或者在我的情况下为scene2d）做它的东西：

Gdx.gl20.glActiveTexture(GL20.GL_TEXTURE0);