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c# - 在 XNA 中画一条永无止境的线

转载 作者:行者123 更新时间:2023-11-30 17:47:00 24 4
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我正在 XNA 中画一条线,我希望它永远不会结束。我还有一个在 X 方向上向前移动的工具和一个以该工具为中心的相机。但是,当我到达视口(viewport)的尽头时,不再绘制线条。这里有一些图片来说明我的问题:

enter image description here

开始时,该行横跨整个屏幕,但随着我的工具向前移动,我们到达了该行的末尾。

画线的方法如下:

        private void DrawEvenlySpacedSprites (Texture2D texture, Vector2 point1, Vector2 point2, float increment)
{
var distance = Vector2.Distance (point1, point2); // the distance between two points
var iterations = (int)(distance / increment); // how many sprites with be drawn
var normalizedIncrement = 1.0f / iterations; // the Lerp method needs values between 0.0 and 1.0
var amount = 0.0f;

if (iterations == 0)
iterations = 1;

for (int i = 0; i < iterations; i++) {
var drawPoint = Vector2.Lerp (point1, point2, amount);
spriteBatch.Draw (texture, drawPoint, Color.White);
amount += normalizedIncrement;
}
}

这里是Game中的draw方法。点是我的线:

protected override void Draw (GameTime gameTime)
{
graphics.GraphicsDevice.Clear(Color.Black);
nyVector = nextVector (gammelVector);
GraphicsDevice.SetRenderTarget (renderTarget);
spriteBatch.Begin ();
DrawEvenlySpacedSprites (dot, gammelVector, nyVector, 0.9F);
spriteBatch.End ();

GraphicsDevice.SetRenderTarget (null);
spriteBatch.Begin (SpriteSortMode.Deferred, BlendState.AlphaBlend, null, null, null, null, camera.transform);
spriteBatch.Draw (renderTarget, new Vector2 (), Color.White);
spriteBatch.Draw (tool, new Vector2(toolPos.X - (tool.Width/2), toolPos.Y - (tool.Height/2)), Color.White);
spriteBatch.End ();

gammelVector = new Vector2 (nyVector.X, nyVector.Y);
base.Draw (gameTime);
}

谁能给我指明正确的方向?我猜它与 viewport.width 有关,但我不太确定如何解决它。感谢阅读!

最佳答案

我读了这篇文章,认为今天早上这会是一个有趣的练习,所以我决定写这篇文章来找乐子。

实现非常简单,不断在彼此的末尾添加行,直到最后一行超出可视区域。

下面的代码将画一条无限向右的线。作为一项额外的优化,屏幕左侧的行会在您经过时被删除。你可以很容易地让它保留以前的线条,或者也创建向左的线条。我将把这些练习留给你。

看看下面的 Line 类,它将在屏幕上定义一条线:

public class Line
{
Texture2D Texture;
Color Color;
public Vector2 PointA;
public Vector2 PointB;
float Width;

public Line(Vector2 pointA, Vector2 pointB, float width, Color color, Texture2D texture)
{
Texture = texture;
PointA = pointA;
PointB = pointB;
Width = width;
Color = color;
}

public void Draw(SpriteBatch spritebatch)
{
float angle = (float)Math.Atan2(PointB.Y - PointA.Y, PointB.X - PointA.X);
float length = Vector2.Distance(PointA, PointB);
spritebatch.Draw(Texture, PointA, null, Color, angle, Vector2.Zero, new Vector2(length, Width), SpriteEffects.None, 0);
}

}

我在游戏类中编写了实现,因为我正在快速编码。您可以在下面看到游戏类:

public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
SpriteBatch spriteBatch;
Camera Camera;

Texture2D LineTexture;
List<Line> Lines;
Random Random;

public Game1()
{
graphics = new GraphicsDeviceManager(this);
Content.RootDirectory = "Content";
}

protected override void Initialize()
{
base.Initialize();
}

protected override void LoadContent()
{
spriteBatch = new SpriteBatch(GraphicsDevice);
Camera = new Camera(GraphicsDevice.Viewport, 1f);

LineTexture = new Texture2D(GraphicsDevice, 1, 1);
LineTexture.SetData<Color>(new Color[] { Color.White });

Random = new Random();
Lines = new List<Line>();
}

protected override void UnloadContent()
{
}


protected override void Update(GameTime gameTime)
{
//handle input
KeyboardState kbState = Keyboard.GetState();

if (kbState.IsKeyDown(Keys.Escape))
this.Exit();

if (kbState.IsKeyDown(Keys.OemMinus))
Camera.Zoom -= 0.015f;
else if (kbState.IsKeyDown(Keys.OemPlus))
Camera.Zoom += 0.015f;

if (kbState.IsKeyDown(Keys.Up))
Camera.Move(new Vector2(0, -30));
else if (kbState.IsKeyDown(Keys.Down))
Camera.Move(new Vector2(0, 30));
if (kbState.IsKeyDown(Keys.Left))
Camera.Move(new Vector2(-30, 0));
else if (kbState.IsKeyDown(Keys.Right))
Camera.Move(new Vector2(30, 0));


//check if line is still in viewport - if not remove it
for (int i = 0; i < Lines.Count; i++)
{
if (Lines[i].PointB.X < Camera.Viewport.X)
{
Lines.RemoveAt(i);
i--;
}
}

//if there are no lines, create one to get started
if (Lines.Count == 0)
{
Vector2 p1 = new Vector2(Camera.Viewport.X, Random.Next(Camera.Viewport.Y + 50, Camera.Viewport.Height - 100));
Vector2 p2 = new Vector2(p1.X + Random.Next(5, 20), p1.Y + Random.Next(-5, 5));
Line line = new Line(p1, p2, 1, Color.Black, LineTexture);
Lines.Add(line);
}

//Check if we need to add some lines to the right of our last list item
while (Lines[Lines.Count - 1].PointB.X < Camera.Viewport.X + Camera.Viewport.Width)
{
Vector2 p1 = new Vector2(Lines[Lines.Count - 1].PointB.X, Lines[Lines.Count - 1].PointB.Y); ;
Vector2 p2 = new Vector2(p1.X + Random.Next(5, 20), p1.Y + Random.Next(-5, 5));
Line line = new Line(p1, p2, 1, Color.Black, LineTexture);
Lines.Add(line);
}

base.Update(gameTime);
}

protected override void Draw(GameTime gameTime)
{
GraphicsDevice.Clear(new Color(30, 90, 150));

spriteBatch.Begin(SpriteSortMode.Deferred, null, null, null, null, null, Camera.View);

foreach (Line line in Lines)
line.Draw(spriteBatch);

spriteBatch.End();

base.Draw(gameTime);
}
}

为了您的方便,我还包含了Camera 类:

public class Camera
{
private const float zoomUpperLimit = 1.5f;
private const float zoomLowerLimit = 0.1f;

private float _zoom;
private Vector2 _pos;

private int ViewportWidth, ViewportHeight;

#region Properties

public float Zoom
{
get { return _zoom; }
set
{
_zoom = value;
if (_zoom < zoomLowerLimit)
_zoom = zoomLowerLimit;
if (_zoom > zoomUpperLimit)
_zoom = zoomUpperLimit;
}
}

public Rectangle Viewport
{
get
{
int width = (int)((ViewportWidth / _zoom));
int height = (int)((ViewportHeight / _zoom));
return new Rectangle((int)(_pos.X - width / 2), (int)(_pos.Y - height / 2), width, height);
}
}

public void Move(Vector2 amount)
{
_pos += amount;
}

public Vector2 Position
{
get { return _pos; }
set { _pos = value; }
}

public Matrix View
{
get
{
return Matrix.CreateTranslation(new Vector3(-_pos.X, -_pos.Y, 0)) *
Matrix.CreateScale(new Vector3(Zoom, Zoom, 1)) *
Matrix.CreateTranslation(new Vector3(ViewportWidth * 0.5f, ViewportHeight * 0.5f, 0));
}
}

#endregion

public Camera(Viewport viewport, float initialZoom)
{
_zoom = initialZoom;
_pos = Vector2.Zero;
ViewportWidth = viewport.Width;
ViewportHeight = viewport.Height;
}

}

关于c# - 在 XNA 中画一条永无止境的线,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25285028/

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