Shows how to render primitive shapes using Batch, without using ShapeRenderer. Requires at least libGDX 1.6.4 or latest nightly.

PolygonShapeTest.java

package com.badlogic.gdx.tests.g2d;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.Color;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.Mesh;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.VertexAttribute;
import com.badlogic.gdx.graphics.VertexAttributes;
import com.badlogic.gdx.graphics.VertexAttributes.Usage;
import com.badlogic.gdx.graphics.g2d.Batch;
import com.badlogic.gdx.graphics.g2d.PolygonSpriteBatch;
import com.badlogic.gdx.graphics.g2d.TextureRegion;
import com.badlogic.gdx.graphics.g3d.utils.MeshBuilder;
import com.badlogic.gdx.graphics.glutils.ShaderProgram;
import com.badlogic.gdx.scenes.scene2d.Actor;
import com.badlogic.gdx.scenes.scene2d.Stage;
import com.badlogic.gdx.scenes.scene2d.ui.Image;
import com.badlogic.gdx.scenes.scene2d.ui.Skin;
import com.badlogic.gdx.scenes.scene2d.ui.TextButton;
import com.badlogic.gdx.scenes.scene2d.utils.Drawable;
import com.badlogic.gdx.tests.utils.GdxTest;
import com.badlogic.gdx.utils.GdxRuntimeException;
import com.badlogic.gdx.utils.viewport.ScreenViewport;

public class PolygonShapeTest extends GdxTest {
	PolygonShapeDrawer drawer;
	PolygonSpriteBatch batch;
	Stage stage;
	Skin skin;
	Actor ellipse;
	TextureRegion white;
	
	@Override
	public void create () {
		drawer = new PolygonShapeDrawer();
		batch = new PolygonSpriteBatch();
		stage = new Stage(new ScreenViewport(), batch);
		skin = new Skin(Gdx.files.internal("data/uiskin.json"));
		white = skin.getAtlas().findRegion("white");
		white.setRegion(white.getRegionX()+1, white.getRegionY()+1, 1, 1);
		
		TextButton button = new TextButton("Behind the shape!", skin);
		button.setPosition(80, 120);
		stage.addActor(button);
		
		ellipse = new Actor() {
			@Override
			public void draw (Batch batch, float parentAlpha) {
				drawer.setTextureRegion(white);
				float w = getWidth(), h = getHeight();
				drawer.setColor(getColor());
				drawer.ellipse(w, h, w * 0.5f, h * 0.5f, 20, getX() + w * 0.5f, getY() + h * 0.5f, 0, 0, 0, -1);
				drawer.draw((PolygonSpriteBatch)batch);
			}
		};
		ellipse.setSize(100, 100);
		ellipse.setPosition(100, 100);
		ellipse.setColor(Color.YELLOW);
		stage.addActor(ellipse);
		
		button = new TextButton("In front of the shape!", skin);
		button.setPosition(80, 160);
		stage.addActor(button);
		
		Gdx.input.setInputProcessor(stage);
	}
	
	@Override
	public void resize (int width, int height) {
		stage.getViewport().update(width, height, true);
	}
	
	@Override
	public void render () {
		stage.act();
		stage.draw();
	}
	
	
	public class PolygonShapeDrawer extends MeshBuilder {
		private Texture texture;
		
		public PolygonShapeDrawer () {
			super();
			super.begin(
				new VertexAttributes(new VertexAttribute(Usage.Position, 2, ShaderProgram.POSITION_ATTRIBUTE), VertexAttribute
					.ColorPacked(), VertexAttribute.TexCoords(0)), GL20.GL_TRIANGLES);
		}

		@Override
		public Mesh end () {
			throw new GdxRuntimeException("Not supported!");
		}

		@Override
		public Mesh end (Mesh mesh) {
			throw new GdxRuntimeException("Not supported!");
		}
		
		public void setTextureRegion (TextureRegion region) {
			if (getNumIndices() > 0)
				throw new GdxRuntimeException("Cannot change the TextureRegion in while creating a shape, call draw first.");
			texture = region.getTexture();
			setUVRange(region);
		}

		public void draw (PolygonSpriteBatch batch) {
			if (texture == null)
				throw new GdxRuntimeException("No texture specified, call setTextureRegion before creating the shape");
			batch.draw(texture, getVertices(), 0, getNumVertices() * getFloatsPerVertex(), getIndices(), 0, getNumIndices());
			clear();
		}
	}
}