创建在XNA二维多边形 [英] Creating a 2D polygon in XNA

问题描述

我有某种形式的问题。我是新来的XNA，并希望绘制多边形形状，看起来像这样（在最后，我想这点是随机的）：

I have some sort of a problem. I'm new to XNA and want to draw a polygon shape that looks something like this (In the end, I want these point to be random):

所以，我读过一些文章，这是我结束了：

So I read some articles and this is what I ended up with:

private VertexPositionColor[] vertices;

public TextureClass()
{
    setupVertices();
}

public override void Render(SpriteBatch spriteBatch)
{
    Texture2D texture = createTexture(spriteBatch);
    spriteBatch.Draw(texture, new Rectangle((int)vertices[0].Position.X, (int)vertices[0].Position.Y, 30, 30), Color.Brown);
}

private Texture2D createTexture(SpriteBatch spriteBatch)
{
    Texture2D texture = new Texture2D(spriteBatch.GraphicsDevice, 1, 1, false, SurfaceFormat.Color);
    texture.SetData<Color>(new Color[] { Color.Brown });
    return texture;
}

当我称之为渲染它开始画一些方块，如果它在一个循环的地方。我只是猜测，我做这一切是错误的。如果某人点我到正确的方向我会喜欢它。只需创建一个多边形和绘图它。它似乎很简单...

When I call Render it's starts drawing some squares as if it where in a loop. I'm just guessing I'm doing it all wrong. I would love it if someones points me into the right direction. Just creating a polygon and drawing it. It seemed so simple...

推荐答案

这就是我现在所拥有的。

Here it what I have right now.

这产生了一些期望asignments一个BasicEffect类

A class that generates a BasicEffect with some desired asignments.

public class StandardBasicEffect : BasicEffect
{
    public StandardBasicEffect(GraphicsDevice graphicsDevice)
        : base(graphicsDevice)
    {
        this.VertexColorEnabled = true;
        this.Projection = Matrix.CreateOrthographicOffCenter(
            0, graphicsDevice.Viewport.Width, graphicsDevice.Viewport.Height, 0, 0, 1);
    }

    public StandardBasicEffect(BasicEffect effect)
        : base(effect) { }

    public BasicEffect Clone()
    {
        return new StandardBasicEffect(this);
    }
}

下面是我PolygonShape类

Here is my PolygonShape class

/// <summary>
/// A Polygon object that you will be able to draw.
/// Animations are being implemented as we speak.
/// </summary>
/// <param name="graphicsDevice">The graphicsdevice from a Game object</param>
/// <param name="vertices">The vertices in a clockwise order</param>
public PolygonShape(GraphicsDevice graphicsDevice, VertexPositionColor[] vertices)
{
    this.graphicsDevice = graphicsDevice;
    this.vertices = vertices;
    this.triangulated = false;

    triangulatedVertices = new VertexPositionColor[vertices.Length * 3];
    indexes = new int[vertices.Length];
}

/// <summary>
/// Triangulate the set of VertexPositionColors so it will be drawn correcrly        
/// </summary>
/// <returns>The triangulated vertices array</returns>}
public VertexPositionColor[] Triangulate()
{
    calculateCenterPoint();{
    setupIndexes();
    for (int i = 0; i < indexes.Length; i++)
    {
        setupDrawableTriangle(indexes[i]);
    }

    triangulated = true;
    return triangulatedVertices;
}

/// <summary>
/// Calculate the center point needed for triangulation.
/// The polygon will be irregular, so this isn't the actual center of the polygon
/// but it will do for now, as we only need an extra point to make the triangles with</summary>
private void calculateCenterPoint()
{
    float xCount = 0, yCount = 0;

    foreach (VertexPositionColor vertice in vertices)
    {
        xCount += vertice.Position.X;
        yCount += vertice.Position.Y;
    }

    centerPoint = new Vector3(xCount / vertices.Length, yCount / vertices.Length, 0);
}

private void setupIndexes()
{
    for (int i = 1; i < triangulatedVertices.Length; i = i + 3)
    {
        indexes[i / 3] = i - 1;
    }
}

private void setupDrawableTriangle(int index)
{
    triangulatedVertices[index] = vertices[index / 3]; //No DividedByZeroException?...
    if (index / 3 != vertices.Length - 1)
        triangulatedVertices[index + 1] = vertices[(index / 3) + 1];
    else
        triangulatedVertices[index + 1] = vertices[0];
    triangulatedVertices[index + 2].Position = centerPoint;
}

/// <summary>
/// Draw the polygon. If you haven't called Triangulate yet, I wil do it for you.
/// </summary>
/// <param name="effect">The BasicEffect needed for drawing</param>
public void Draw(BasicEffect effect)
{
    try
    {
        if (!triangulated)
            Triangulate();

        draw(effect);
    }
    catch (Exception exception)
    {
        throw exception;
    }
}

private void draw(BasicEffect effect)
{
    effect.CurrentTechnique.Passes[0].Apply();
    graphicsDevice.DrawUserPrimitives<VertexPositionColor>(
        PrimitiveType.TriangleList, triangulatedVertices, 0, vertices.Length);
}

对不起，它是一种很多。现在我的下一个任务。动画我的多边形。

Sorry, it's kind of alot. Now for my next quest. Animation my polygon.

希望它帮助同胞的人同样的问题。

Hope it helped fellow people with the same problem.

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