libgdx 裁剪多边形(clip polygon、masking polygon)

public static void drawClip(Batch batch, Polygon polygon, TextureRegion region, float x, float y) {
float[] vertices = polygon.getVertices();
if (shapes == null) {
shapes = new ShapeRenderer();
}
//2. clear our depth buffer with 1.0
Gdx.gl.glClearDepthf(1f);
Gdx.gl.glClear(GL20.GL_DEPTH_BUFFER_BIT);

//3. set the function to LESS
Gdx.gl.glDepthFunc(GL20.GL_LESS);

//4. enable depth writing
Gdx.gl.glEnable(GL20.GL_DEPTH_TEST);

//5. Enable depth writing, disable RGBA color writing
Gdx.gl.glDepthMask(true);
Gdx.gl.glColorMask(false, false, false, false);

///////////// Draw mask shape(s)

//6. render your primitive shapes
shapes.begin(ShapeRenderer.ShapeType.Filled);

shapes.setColor(1f, 0f, 0f, 0.5f);
shapes.identity();
shapes.triangle(vertices[0], vertices[1], vertices[4], vertices[5], vertices[2], vertices[3]);
shapes.triangle(vertices[0], vertices[1], vertices[4], vertices[5], vertices[6], vertices[7]);
//        shapes.polyline(polygon.getVertices());

shapes.end();

///////////// Draw sprite(s) to be masked
if (!batch.isDrawing()) {
batch.begin();
}

//8. Enable RGBA color writing
//   (SpriteBatch.begin() will disable depth mask)
Gdx.gl.glColorMask(true, true, true, true);

//9. Make sure testing is enabled.
Gdx.gl.glEnable(GL20.GL_DEPTH_TEST);

//10. Now depth discards pixels outside our masked shapes
Gdx.gl.glDepthFunc(GL20.GL_EQUAL);

//push to the batch
batch.draw(region, x, y);
//end/flush your batch
batch.end();
Gdx.gl.glDisable(GL20.GL_DEPTH_TEST);
}