using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;

namespace MMCG_lab4_MESH_
{
    public class BSplineSurface
    {
        private double size;
        private const int m = 4;
        private Point3D start = new Point3D(300, 210, 0);
        private double psi;
        private double phi;
        public BSplineSurface(double size, double psi, double phi)
        {
            this.size = size;
            this.psi = psi;
            this.phi = phi;
        }
        Point3D[][] mBSplineSurface = new Point3D[][] {
                new Point3D[] { new Point3D(0, 0, 0), new Point3D(0, 0, 1), new Point3D(0, 1, 0), new Point3D(0, 1, 1) }, 
                new Point3D[] { new Point3D(0.5, 0, 0), new Point3D(0.5, 0, 0.5), new Point3D(0.5, 0.5, 0), new Point3D(0.5, 0.5, 0.5) }, 
                new Point3D[] { new Point3D(1, 0, 0), new Point3D(1, 0, 1), new Point3D(1, 1, 0), new Point3D(1, 1, 1) }
        };
        private PointF Project(Point3D p)
        {
            Point3D e1 = new Point3D(Math.Cos(phi), Math.Sin(phi), 0);
            Point3D e2 = new Point3D(-1 * Math.Sin(phi) * Math.Sin(psi), Math.Cos(phi) * Math.Sin(psi), Math.Cos(psi));
            double x = p.X - start.X;
            double y = p.Y - start.Y;
            double z = p.Z - start.Z;
            return new PointF((float)(e1.scal(new Point3D(x, y, z)) * size), (float)(e2.scal(new Point3D(x, y, z)) * size));

        }
        public void Show(Graphics g, Pen pen)
        {
            List<Point3D> polygon = new List<Point3D>();
            for (double u = 0; u <= 1.0; u += 0.01)
            {
                for (double v = 0; v <= 1.0; v += 0.01)
                {
                    var pList = new List<Point3D>();
                    for (int i = 0; i < mBSplineSurface.Length; i++)
                    {
                        for (int j = 0; j < mBSplineSurface.Length - 2; j++)
                        {
                            pList.Add(new Point3D((float)(0.5f * (1f - v) * (1f - v) * mBSplineSurface[i][j].X + (0.75f - (v - 0.5f) * (v - 0.5f)) * mBSplineSurface[i][j + 1].X + 0.5f * v * v * mBSplineSurface[i][j + 2].X),
                                (float)(0.5f * (1f - v) * (1f - v) * mBSplineSurface[i][j].Y + (0.75f - (v - 0.5f) * (v - 0.5f)) * mBSplineSurface[i][j + 1].Y + 0.5f * v * v * mBSplineSurface[i][j + 2].Y),
                                (float)(0.5f * (1f - v) * (1f - v) * mBSplineSurface[i][j].Z + (0.75f - (v - 0.5f) * (v - 0.5f)) * mBSplineSurface[i][j + 1].Z + 0.5f * v * v * mBSplineSurface[i][j + 2].Z)));
                        }
                    }
                    for (int j = 0; j < pList.Count - 2; j++)
                    {
                        polygon.Add(new Point3D((float)(0.5f * (1f - u) * (1f - u) * pList[j].X + (0.75f - (u - 0.5f) * (u - 0.5f)) * pList[j + 1].X + 0.5f * u * u * pList[j + 2].X),
                            (float)(0.5f * (1f - u) * (1f - u) * pList[j].Y + (0.75f - (u - 0.5f) * (u - 0.5f)) * pList[j + 1].Y + 0.5f * u * u * pList[j + 2].Y),
                            (float)(0.5f * (1f - u) * (1f - u) * pList[j].Z + (0.75f - (u - 0.5f) * (u - 0.5f)) * pList[j + 1].Z + 0.5f * u * u * pList[j + 2].Z)));
                        polygon.Last().X = (float)(polygon.Last().X  + start.X);
                        polygon.Last().Y = (float)(polygon.Last().Y  + start.Y);
                        polygon.Last().Z = (float)(polygon.Last().Z  + start.Z);
                    }
                }
                var sub = polygon.Select(x => Project(x)).ToList();
                for (int i = 0; i < sub.Count - 1; i++)
                {
                    if (g.ClipBounds.Contains(sub[i]) && g.ClipBounds.Contains(sub[i + 1]))
                    {
                        g.DrawLine(pen, sub[i], sub[i + 1]);
                    }
                }
                polygon.Clear();
            }
            for (double v = 0; v <= 1.0; v += 0.01)
            {
                for (double u = 0; u <= 1.0; u += 0.01)
                {
                    var pList = new List<Point3D>();
                    for (int i = 0; i < mBSplineSurface.Length; i++)
                    {
                        for (int j = 0; j < mBSplineSurface.Length - 2; j++)
                        {
                            pList.Add(new Point3D((float)(0.5f * (1f - v) * (1f - v) * mBSplineSurface[i][j].X + (0.75f - (v - 0.5f) * (v - 0.5f)) * mBSplineSurface[i][j + 1].X + 0.5f * v * v * mBSplineSurface[i][j + 2].X),
                                (float)(0.5f * (1f - v) * (1f - v) * mBSplineSurface[i][j].Y + (0.75f - (v - 0.5f) * (v - 0.5f)) * mBSplineSurface[i][j + 1].Y + 0.5f * v * v * mBSplineSurface[i][j + 2].Y),
                                (float)(0.5f * (1f - v) * (1f - v) * mBSplineSurface[i][j].Z + (0.75f - (v - 0.5f) * (v - 0.5f)) * mBSplineSurface[i][j + 1].Z + 0.5f * v * v * mBSplineSurface[i][j + 2].Z)));
                        }
                    }
                    for (int j = 0; j < pList.Count - 2; j++)
                    {
                        polygon.Add(new Point3D((float)(0.5f * (1f - u) * (1f - u) * pList[j].X + (0.75f - (u - 0.5f) * (u - 0.5f)) * pList[j + 1].X + 0.5f * u * u * pList[j + 2].X),
                            (float)(0.5f * (1f - u) * (1f - u) * pList[j].Y + (0.75f - (u - 0.5f) * (u - 0.5f)) * pList[j + 1].Y + 0.5f * u * u * pList[j + 2].Y),
                            (float)(0.5f * (1f - u) * (1f - u) * pList[j].Z + (0.75f - (u - 0.5f) * (u - 0.5f)) * pList[j + 1].Z + 0.5f * u * u * pList[j + 2].Z)));
                        polygon.Last().X = (float)(polygon.Last().X  + start.X);
                        polygon.Last().Y = (float)(polygon.Last().Y  + start.Y);
                        polygon.Last().Z = (float)(polygon.Last().Z  + start.Z);
                    }
                }
                var sub = polygon.Select(x => Project(x)).ToList();
                for (int i = 0; i < sub.Count - 1; i++)
                {
                    if (g.ClipBounds.Contains(sub[i]) && g.ClipBounds.Contains(sub[i + 1]))
                    {
                        g.DrawLine(pen, sub[i], sub[i + 1]);
                    }
                }
                polygon.Clear();
            }
        }
    }
}