使用libgdx绘制填充多边形

Question

我想用libgdx绘制一些(填充的)多边形用于Android游戏.它不应该充满图形/纹理.我只有多边形(闭合路径)的顶点,并试图与网格的可视化,但在某些时候,这不是最好的解决办法,我想.

我的矩形代码是:

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);
}

是否有一个函数或东西以更简单的方式绘制填充多边形？

Answer 1

自从最近更新LibGDX以来,@ Rus的答案正在使用已弃用的函数.但是,我将为他/她提供以下新版本的学分:

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();

对于良好的三角测量算法,如果多边形不是凸面,请参阅Toussaint(1991)的几乎线性的咬合算法

简单多边形的有效三角剖分,Godfried Toussaint,1991

Answer 2

这是一个绘制2D凹多边形的LIBGDX示例.

//为PolygonSprite PolygonSpriteBatch定义类成员

PolygonSprite poly;
PolygonSpriteBatch polyBatch;
Texture textureSolid;

//创建实例,1x1大小纹理与红色像素一起使用作为变通方法,(x,y)用于初始化poly的coords数组

ctor() {
    textureSolid = makeTextureBox(1, 0xFFFF0000, 0, 0); 
    float a = 100;
    float b = 100;
    PolygonRegion polyReg = new PolygonRegion(new TextureRegion(textureSolid),
      new float[] {
        a*0, b*0,
        a*0, b*2,
        a*3, b*2,
        a*3, b*0,
        a*2, b*0,
        a*2, b*1,
        a*1, b*1,
        a*1, b*0,
    });
    poly = new PolygonSprite(polyReg);
    poly.setOrigin(a, b);
    polyBatch = new PolygonSpriteBatch();
}

//绘制并旋转多边形

void draw() {
    super.draw();
    polyBatch.begin();
    poly.draw(polyBatch);
    polyBatch.end();
    poly.rotate(1.1f);
}