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

namespace MMCG_lab_8_9
{
    class ZBuffer
    {
        private int sX, sY;
        private double[] zbuffer;
        private double[,] Zbuf;
        private Color[,] ZColor;
        private const double ph = 10 * Math.PI / 180;
        private const double ps = 50 * Math.PI / 180;
        private Point3D e1 = new Point3D(Math.Cos(ph), Math.Sin(ph), 0);
        private Point3D e2 = new Point3D(-1 * Math.Sin(ph) * Math.Sin(ps), Math.Cos(ph) * Math.Sin(ps), Math.Sin(ps)); 
        public ZBuffer(int WIDTH, int HEIGHT)
        {
            sX = WIDTH;
            sY = HEIGHT;
            zbuffer = new double[sX * sY];
            for (int i = 0; i < sX * sY; i++)
                zbuffer[i] = -32000;
            Zbuf = new double[sX, sY];
            ZColor = new Color[sX, sY];
            for (int i = 0; i < sX; i++)
                for (int j = 0; j < sY; j++)
                    Zbuf[i, j] = 32000;
        }
        public void Show(List<Triangle> t, Graphics g)
        {
            for (int i = 0; i < t.Count; i++)
               ZBuffPart(t[i]);
               //DrawTriangle(t[i], g, t[i].color);
            for (int i = 0; i < sX; i++)
                for (int j = 0; j < sY; j++)
                    g.DrawRectangle(new Pen(ZColor[i, j]), i, j, 1, 1);
        }
        private void ZBuffPart(Triangle t)
        {
            double u, v, du, dv;
            int x, y;
            Point3D R = new Point3D(0, 0, 0);
            du = 0.007;
            dv = 0.007;
            for (u = 0; u <= 1.0; u += du)
                for (v = 0; v <= 1.0 - u; v += dv)
                {
                    R.X = t.A.X + u * (t.B.X - t.A.X) + v * (t.C.X - t.A.X);
                    R.Y = t.A.Y + u * (t.B.Y - t.A.Y) + v * (t.C.Y - t.A.Y);
                    R.Z = t.A.Z + u * (t.B.Z - t.A.Z) + v * (t.C.Z - t.A.Z);
                    x = (int)Math.Round(R.scal(e1));
                    y = (int)Math.Round(R.scal(e2));
                    if (Zbuf[x, y] > R.Z)
                    {
                        Zbuf[x, y] = R.Z;
                        ZColor[x, y] = t.color;
                    }
                }
        }
        public void DrawTriangle(Triangle t, Graphics g, Color color)
        {
            if (t.A.Y == t.B.Y && t.A.Y == t.C.Y) return;
            if (t.A.Y > t.B.Y) { Point3D tmp; tmp = t.A; t.A = t.B; t.B = tmp; }
            if (t.A.Y > t.C.Y) { Point3D tmp; tmp = t.A; t.A = t.C; t.C = tmp; }
            if (t.B.Y > t.C.Y) { Point3D tmp; tmp = t.B; t.B = t.C; t.C = tmp; }
            int total_height = (int)Math.Round(t.C.Y - t.A.Y);
            for (int i = 0; i < total_height; i++)
            {
                bool second_half = i > t.B.Y - t.A.Y || t.B.Y == t.A.Y;
                int segment_height = second_half ? (int)Math.Round(t.C.Y - t.B.Y) : (int)Math.Round(t.B.Y - t.A.Y);
                float alpha = (float)i / total_height;
                //alpha = Math.Abs(alpha);
                float beta = (float)(i - (second_half ? t.B.Y - t.A.Y : 0)) / segment_height;
                //beta = Math.Abs(beta);
                Point3D A = new Point3D(t.A.X + (t.C.X - t.A.X) * alpha,
                                        t.A.Y + (t.C.Y - t.A.Y) * alpha,
                                        t.A.Z + (t.C.Z - t.A.Z) * alpha);
                Point3D B = second_half ? new Point3D(t.B.X + (t.C.X - t.B.X) * beta,
                                                      t.B.Y + (t.C.Y - t.B.Y) * beta,
                                                      t.B.Z + (t.C.Z - t.B.Z) * beta)
                                                      :
                                          new Point3D(t.A.X + (t.B.X - t.A.X) * beta,
                                                      t.A.Y + (t.B.Y - t.A.Y) * beta,
                                                      t.A.Z + (t.B.Z - t.A.Z) * beta);
                if (A.X > B.X) { Point3D tmp; tmp = A; A = B; B = tmp; }
                for (int j = (int)(A.X); j <= (int)(B.X); j++)
                {
                    float phi = B.X == A.X ? 1.0f : (float)(j - A.X) / (float)(B.X - A.X);
                    //phi = Math.Abs(phi);
                    Point3D P = new Point3D(A.X + (B.X - A.X) * phi,
                                            A.Y + (B.Y - A.Y) * phi,
                                            A.Z + (B.Z - A.Z) * phi);
                    int idx = (int)(Math.Round(P.X * sX + P.Y));
                    if (zbuffer[idx] < P.Z)
                    {
                        zbuffer[idx] = P.Z;
                        g.DrawRectangle(new Pen(color), (int)j, (int)Math.Round(t.A.Y + i), 1, 1);
                    }
                }
            }
        }
    }
}