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标题:抛体运动2
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zanzan1986
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你的抛物线是用二次函数来写的么?????????
图形开发是用OpenGL么???????
如果全用二次函数来写的话抛物线会有齿轮现象。。。。。。。。。。。。。。。。。。。。。。
动画是用线程来写的还是用计时器写的啊!!!!!!!!!!!!!!!!
2012-05-02 15:59
beyondyf
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1、抛物线本来就是一个二次函数
2、图形用GDI+写的。随手写着玩的东西,并不涉及很深的图形算法。
3、当采样点越多矩齿现象就越小,图像越精致。GDI+中本身也带有消除矩齿的函数,不过这里并不很需要。
4、使用计时器来写的,这个小东西不需要多线程。在图像绘制过程中我不允许鼠标按键再响应绘制新图。

本不想发C#代码在C论坛里。不过没有代码算法交流起来很不方便,这里把程序的主要部分发上来吧。其实有C++底子的话,C#代码并不难看懂。

程序代码:
namespace Beyondyf
{
    public partial class MainForm : Form
    {
        public MainForm()
        {
            InitializeComponent();
        }

        private void MainForm_Load(object sender, EventArgs e)
        {
            ox = 100;
            oy = 500;

            bgColor = Color.Black;

            brushArrow = new SolidBrush(Color.Red);
            brushBall = new SolidBrush(Color.Pink);
            brushLine = new SolidBrush(Color.Yellow);
            penLine = new Pen(brushLine);
            map = new Bitmap(this.ClientSize.Width, this.ClientSize.Height);
            gMap = Graphics.FromImage(map);
            gMap.Clear(bgColor);
            DrawBall(gMap, ox, oy);
            gShow = this.CreateGraphics();

            timer = new Timer();
            timer.Tick += new EventHandler(DrawPath);
            timer.Interval = 20;
            setting = false;
        }

        private void MainForm_Paint(object sender, PaintEventArgs e)
        {
            gShow.DrawImage(map, 0, 0);
        }

        private void MainForm_MouseDown(object sender, MouseEventArgs e)
        {
            if (setting) return;

            int dx = e.X - ox;
            int dy = e.Y - oy;
            double length = Math.Sqrt(dx * dx + dy * dy);
            double angle = length < 1 ? 0 : Math.Asin(dy / length);
            if (dx < 0) angle = Math.PI - angle;
            if (length < 1) velocity = 0;
            else if (length > 300) velocity = 300;
            else velocity = length;
            initAngle = -angle;

            gMap.Clear(bgColor);
            DrawArrow(gMap, ox, oy, velocity, angle);
            DrawBall(gMap, ox, oy);
            gShow.DrawImage(map, 0, 0);

        }

        private void MainForm_MouseMove(object sender, MouseEventArgs e)
        {
            if (!setting && (e.Button & System.Windows.Forms.MouseButtons.Left) != 0)
            {
                int dx = e.X - ox;
                int dy = e.Y - oy;
                double length = Math.Sqrt(dx * dx + dy * dy);
                double angle = length < 1 ? 0 : Math.Asin(dy / length);
                if (dx < 0) angle = Math.PI - angle;
                if (length < 1) velocity = 0;
                else if (length > 300) velocity = 300;
                else velocity = length;
                initAngle = -angle;

                gMap.Clear(bgColor);
                DrawArrow(gMap, ox, oy, velocity, angle);
                DrawBall(gMap, ox, oy);
                gShow.DrawImage(map, 0, 0);
            }
        }

        private void MainForm_MouseUp(object sender, MouseEventArgs e)
        {
            if (!setting)
            {
                setting = true;
                prb = new Parabola(velocity, initAngle, 1, 1000);
                timer.Start();
            }
        }

        private void DrawBall(Graphics g, float x, float y)
        {
            g.FillEllipse(brushBall, x - 10, y - 10, 20, 20);
        }

        private void DrawArrow(Graphics g, float x, float y, double length, double angle)
        {
            Point[] ps = new Point[3];
            ps[0].X = (int)(8 * Math.Cos(angle - Math.PI / 2) + x + 0.5);
            ps[0].Y = (int)(8 * Math.Sin(angle - Math.PI / 2) + y + 0.5);
            ps[1].X = (int)(8 * Math.Cos(angle + Math.PI / 2) + x + 0.5);
            ps[1].Y = (int)(8 * Math.Sin(angle + Math.PI / 2) + y + 0.5);
            ps[2].X = (int)(length * Math.Cos(angle) + x + 0.5);
            ps[2].Y = (int)(length * Math.Sin(angle) + y + 0.5);
            g.FillPolygon(brushArrow, ps);
        }

        private void DrawLine(Graphics g, Parabola p, int count)
        {
            for (int i = 1; i <= count; i++)
                g.DrawLine(penLine, p.X(i - 1, rate) + ox, oy - p.Y(i - 1, rate), p.X(i, rate) + ox, oy - p.Y(i, rate));
        }

        private void DrawPath(object sender, EventArgs e)
        {
            gMap.Clear(bgColor);
            DrawLine(gMap, prb, count);
            DrawBall(gMap, prb.X(count, rate) + ox, oy - prb.Y(count, rate));
            gShow.DrawImage(map, 0, 0);
            if (prb.Y(count, rate) < oy - 700)
            {
                timer.Stop();
                count = 0;
                setting = false;
            }
            else count++;
        }

        private Timer timer;

        private Parabola prb;

        private bool setting;
        private double velocity;
        private double initAngle;
        private int count;

        private const double rate = 10;

        private Bitmap map;
        private Graphics gMap;
        private Graphics gShow;
        private int ox;
        private int oy;
        private Color bgColor;
        private Brush brushArrow;
        private Brush brushBall;
        private Brush brushLine;
        private Pen penLine;
    }

    public class Parabola
    {
        public Parabola(double velocity, double angle, double timeStep, int stepCount)
        {
            x = new double[stepCount + 1];
            y = new double[stepCount + 1];
            double vx = velocity * Math.Cos(angle) * timeStep;
            double vy = velocity * Math.Sin(angle) * timeStep;
            double a = -9.8 / 2 * timeStep * timeStep;
            for (int i = 0; i <= stepCount; i++)
            {
                x[i] = vx * i;
                y[i] = vy * i + a * i * i;
            }
        }

        public float X(int index, double rate)
        {
            if (index < 0 && index >= x.Length) return 0;
            return (float)(x[index] / rate);
        }

        public float Y(int index, double rate)
        {
            if (index < 0 && index >= y.Length) return 0;
            return (float)(y[index] / rate);
        }

        private double[] x;
        private double[] y;
    }
}


重剑无锋,大巧不工
2012-05-02 18:54
快速回复:抛体运动2
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