SkiaSharp 之 WPF 自绘 投篮小游戏（案例版）

此案例主要是针对光线投影法碰撞检测功能的示例，顺便做成了一个小游戏，很简单，但是，效果却很不错。

投篮小游戏

规则，点击投篮目标点，就会有一个球沿着相关抛物线，然后，判断是否进入篮子里，其实就是一个矩形，直接是按照碰撞检测来的，碰到就算进去了，对其增加了一个分数统计等功能。

Wpf 和 SkiaSharp

新建一个 WPF 项目，然后，Nuget 包即可

要添加 Nuget 包

Install-Package SkiaSharp.Views.WPF -Version 2.88.0

其中核心逻辑是这部分，会以我设置的 60FPS 来刷新当前的画板。

skContainer.PaintSurface += SkContainer_PaintSurface;
_ = Task.Run(() =>
{
    while (true)
    {
        try
        {
            Dispatcher.Invoke(() =>
            {
                skContainer.InvalidateVisual();
            });
            _ = SpinWait.SpinUntil(() => false, 1000 / 60);//每秒60帧
        }
        catch
        {
            break;
        }
    }
});

弹球实体代码 (Ball.cs)

public class Ball
{
    public double X { get; set; }
    public double Y { get; set; }
    public double VX { get; set; }
    public double VY { get; set; }
    public int Radius { get; set; }
}

粒子花园核心类 (ParticleGarden.cs)

/// <summary>
/// 光线投影法碰撞检测
/// 投篮小游戏
/// </summary>
public class RayProjection
{
    public SKPoint centerPoint;
    public double G = 0.3;
    public double F = 0.98;
    public double Easing = 0.03;
    public bool IsMoving = false;
    public SKPoint CurrentMousePoint = SKPoint.Empty;
    public SKPoint lastPoint = SKPoint.Empty;
    public Rect Box;
    public Ball Ball;
    public SKCanvas canvas;
    public int ALLCount = 10;
    public List<bool> bools = new List<bool>();
    public bool IsOver = false;
    /// <summary>
    /// 渲染
    /// </summary>
    public void Render(SKCanvas canvas, SKTypeface Font, int Width, int Height)
    {
        canvas.Clear(SKColors.White);
        this.canvas = canvas;
        centerPoint = new SKPoint(Width / 2, Height / 2);
        //球
        if (Ball == null)
        {
            Ball = new Ball()
            {
                X = 50,
                Y = Height - 50,
                Radius = 30
            };
        }
        //箱子
        var boxX = Width - 170;
        var boxY = Height - 80;
        if (Box.X == 0)
        {
            Box = new Rect(boxX, boxY, 120, 70);
        }
        else
        {
            if (Box.X != boxX && Box.Y != boxY)
            {
                Box.X = boxX;
                Box.Y = boxY;
            }
        }

        if (bools.Count >= ALLCount)
        {
            IsOver = true;
        }

        if (!IsOver)
        {
            if (IsMoving)
            {
                BallMove(Width, Height);
            }
            else
            {
                DrawLine();
            }

            //弹球
            DrawCircle(canvas, Ball);
            //矩形
            DrawRect(canvas, Box);

            //计分
            using var paint1 = new SKPaint
            {
                Color = SKColors.Blue,
                IsAntialias = true,
                Typeface = Font,
                TextSize = 24
            };
            string count = $"总次数:{ALLCount} 剩余次数:{ALLCount - bools.Count} 投中次数:{bools.Count(t => t)}";
            canvas.DrawText(count, 100, 20, paint1);
        }
        else
        {
            SKColor sKColor = SKColors.Blue;
            //计分
            var SuccessCount = bools.Count(t => t);
            string count = "";
            switch (SuccessCount)
            {
                case 0:
                    {
                        count = $"太糗了吧，一个都没投中！";
                        sKColor = SKColors.Black;
                    }
                    break;
                case 1:
                case 2:
                case 3:
                case 4:
                case 5:
                    {
                        count = $"你才投中:{SuccessCount}次，继续努力！";
                        sKColor = SKColors.Blue;
                    }
                    break;
                case 6:
                case 7:
                case 8:
                case 9:
                    {
                        count = $"恭喜 投中:{SuccessCount}次!!!";
                        sKColor = SKColors.YellowGreen;
                    }
                    break;
                case 10: { count = $"全部投中，你太厉害了!";
                        sKColor = SKColors.Red;
                    } break;
            }
            using var paint1 = new SKPaint
            {
                Color = sKColor,
                IsAntialias = true,
                Typeface = Font,
                TextSize = 48
            };
            var fontCenter = paint1.MeasureText(count);
            canvas.DrawText(count, centerPoint.X - fontCenter / 2, centerPoint.Y, paint1);
        }
        using var paint = new SKPaint
        {
            Color = SKColors.Blue,
            IsAntialias = true,
            Typeface = Font,
            TextSize = 24
        };
        string by = $"by 蓝创精英团队";
        canvas.DrawText(by, 600, 20, paint);
    }
    /// <summary>
    /// 画一个圆
    /// </summary>
    public void DrawCircle(SKCanvas canvas, Ball ball)
    {
        using var paint = new SKPaint
        {
            Color = SKColors.Blue,
            Style = SKPaintStyle.Fill,
            IsAntialias = true,
            StrokeWidth = 2
        };
        canvas.DrawCircle((float)ball.X, (float)ball.Y, ball.Radius, paint);
    }
    /// <summary>
    /// 画一个矩形
    /// </summary>
    public void DrawRect(SKCanvas canvas, Rect box)
    {
        using var paint = new SKPaint
        {
            Color = SKColors.Green,
            Style = SKPaintStyle.Fill,
            IsAntialias = true,
            StrokeWidth = 2
        };
        canvas.DrawRect((float)box.X, (float)box.Y, (float)box.Width, (float)box.Height, paint);
    }
    /// <summary>
    /// 划线
    /// </summary>
    public void DrawLine()
    {
        //划线
        using var LinePaint = new SKPaint
        {
            Color = SKColors.Red,
            Style = SKPaintStyle.Fill,
            StrokeWidth = 2,
            IsStroke = true,
            StrokeCap = SKStrokeCap.Round,
            IsAntialias = true
        };
        var path = new SKPath();
        path.MoveTo((float)CurrentMousePoint.X, (float)CurrentMousePoint.Y);
        path.LineTo((float)Ball.X, (float)Ball.Y);
        path.Close();
        canvas.DrawPath(path, LinePaint);
    }
    public void BallMove(int Width, int Height)
    {
        Ball.VX *= F;
        Ball.VY *= F;
        Ball.VY += G;

        Ball.X += Ball.VX;
        Ball.Y += Ball.VY;

        var hit = CheckHit();
        // 边界处理和碰撞检测
        if (hit || Ball.X - Ball.Radius > Width || Ball.X + Ball.Radius < 0 || Ball.Y - Ball.Radius > Height || Ball.Y + Ball.Radius < 0)
        {
            bools.Add(hit);
            IsMoving = false;
            Ball.X = 50;
            Ball.Y = Height - 50;
        }

        lastPoint.X = (float)Ball.X;
        lastPoint.Y = (float)Ball.Y;
    }
    public bool CheckHit()
    {
        var k1 = (Ball.Y - lastPoint.Y) / (Ball.X - lastPoint.X);
        var b1 = lastPoint.Y - k1 * lastPoint.X;
        var k2 = 0;
        var b2 = Ball.Y;
        var cx = (b2 - b1) / (k1 - k2);
        var cy = k1 * cx + b1;
        if (cx - Ball.Radius / 2 > Box.X && cx + Ball.Radius / 2 < Box.X + Box.Width && Ball.Y - Ball.Radius > Box.Y)
        {
            return true;
        }
        return false;
    }
    public void MouseMove(SKPoint sKPoint)
    {
        CurrentMousePoint = sKPoint;
    }
    public void MouseDown(SKPoint sKPoint)
    {
        CurrentMousePoint = sKPoint;
    }
    public void MouseUp(SKPoint sKPoint)
    {
        if (bools.Count < ALLCount)
        {
            IsMoving = true;
            Ball.VX = (sKPoint.X - Ball.X) * Easing;
            Ball.VY = (sKPoint.Y - Ball.Y) * Easing;
            lastPoint.X = (float)Ball.X;
            lastPoint.Y = (float)Ball.Y;
        }
    }
}

效果如下:

还不错，得了7分，当然，我也可以得10分的，不过，还好了。

总结

这个特效的案例重点是光线投影法碰撞检测，同时又对其增加了游戏的属性，虽然东西都很简单，但是作为一个雏形来讲也是不错的。

SkiaSharp 基础系列算是告一段落了，基础知识相关暂时都已经有了一个深度的了解，对于它的基础应用已经有一个不错的认识了，那么，基于它的应用应该也会多起来，我这边主要参考Avalonia的内部SkiaSharp使用原理，当然，用法肯定不局限的。

代码地址

https://github.com/kesshei/WPFSkiaRayProjectionDemo.git

https://gitee.com/kesshei/WPFSkiaRayProjectionDemo.git

阅

一键三连呦！，感谢大佬的支持，您的支持就是我的动力!

版权

蓝创精英团队（公众号同名，CSDN 同名，CNBlogs 同名）