Drawing filled polygon with libGDX

Question

I want to draw some (filled) polygons with libGDX. It shoudn't be filled with a graphic/texture. I have only the vertices of the polygon (closed path) and tried to visualize with meshes but at some point this is not the best solution, I think.

My code for an rectangle is:

private Mesh mesh;

@Override
public void create() {
    if (mesh == null) {
        mesh = new Mesh(
            true, 4, 0, 
            new VertexAttribute(Usage.Position, 3, "a_position")
        );
        mesh.setVertices(new float[] { 
            -0.5f, -0.5f, 0
            0.5f, -0.5f, 0,
            -0.5f, 0.5f, 0,
            0.5f, 0.5f, 0 
        });     
    }
}

// ...

@Override
public void render() {
    Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
    mesh.render(GL10.GL_TRIANGLE_STRIP, 0, 4);
}

is there a function or something to draw filled polygons in an easier way?

Answer 1

Since recent updates of LibGDX, @Rus answer is using deprecated functions. However, I give him/her credits for the new updated version below:

PolygonSprite poly;
PolygonSpriteBatch polyBatch = new PolygonSpriteBatch(); // To assign at the beginning
Texture textureSolid;

// Creating the color filling (but textures would work the same way)
Pixmap pix = new Pixmap(1, 1, Pixmap.Format.RGBA8888);
pix.setColor(0xDEADBEFF); // DE is red, AD is green and BE is blue.
pix.fill();
textureSolid = new Texture(pix);
PolygonRegion polyReg = new PolygonRegion(new TextureRegion(textureSolid),
  new float[] {      // Four vertices
    0, 0,            // Vertex 0         3--2
    100, 0,          // Vertex 1         | /|
    100, 100,        // Vertex 2         |/ |
    0, 100           // Vertex 3         0--1
}, new short[] {
    0, 1, 2,         // Two triangles using vertex indices.
    0, 2, 3          // Take care of the counter-clockwise direction. 
});
poly = new PolygonSprite(polyReg);
poly.setOrigin(a, b);
polyBatch = new PolygonSpriteBatch();

For good triangulating algorithms if your polygon is not convex, see the almost-linear earclipping algorithm from Toussaint (1991)

Efficient triangulation of simple polygons, Godfried Toussaint, 1991