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using UnityEngine;
using System.Collections;

public class experiments : MonoBehaviour
{
    public float Radius = 1.0f;
    public Transform Sphere;
    public Transform Camera;

    public Transform P0;
    public Transform P1;
    public Transform P2;
    public Transform P3;

    bool LiangBarsky(float edgeLeft, float edgeRight, float edgeBottom, float edgeTop,   // Define the x/y clipping values for the border.
                   float x0src, float y0src, float x1src, float y1src,                 // Define the start and end points of the line.
                   ref float x0clip, ref float y0clip, ref float x1clip, ref float y1clip)         // The output values, so declare these outside.
    {

        float t0 = 0.0f;
        float t1 = 1.0f;
        float xdelta = x1src - x0src;
        float ydelta = y1src - y0src;
        float p = 0;
        float q = 0;
        float r = 0;

        for (int edge = 0; edge < 4; edge++)
        {
            // Traverse through left, right, bottom, top edges.
            if (edge == 0) { p = -xdelta; q = -(edgeLeft - x0src); }
            if (edge == 1) { p = xdelta; q = (edgeRight - x0src); }
            if (edge == 2) { p = -ydelta; q = -(edgeBottom - y0src); }
            if (edge == 3) { p = ydelta; q = (edgeTop - y0src); }
            r = q / p;
            if (p == 0 && q < 0) return false;   // Don't draw line at all. (parallel line outside)

            if (p < 0)
            {
                if (r > t1) return false;         // Don't draw line at all.
                else if (r > t0) t0 = r;            // Line is clipped!
            }
            else if (p > 0)
            {
                if (r < t0) return false;      // Don't draw line at all.
                else if (r < t1) t1 = r;         // Line is clipped!
            }
        }

        x0clip = x0src + t0 * xdelta;
        y0clip = y0src + t0 * ydelta;
        x1clip = x0src + t1 * xdelta;
        y1clip = y0src + t1 * ydelta;

        return true;        // (clipped) line is drawn
    }

    bool PackedLiangBarsky(float edgeLeft, float edgeRight, float edgeBottom, float edgeTop,   // Define the x/y clipping values for the border.
                   Vector2 src0, Vector2 src1,                 // Define the start and end points of the line.
                   ref Vector2 clip0, ref Vector2 clip1)         // The output values, so declare these outside.
    {
        float t0 = 0.0f;
        float t1 = 1.0f;
        Vector2 delta = src1 - src0;

        for (int edge = 0; edge < 4; edge++)
        {
            float p = 0;
            float q = 0;
            float r = 0;
            // Traverse through left, right, bottom, top edges.
            if (edge == 0) { p = -delta.x; q = -(edgeLeft   - src0.x); }
            if (edge == 1) { p =  delta.x; q =  (edgeRight  - src0.x); }
            if (edge == 2) { p = -delta.y; q = -(edgeBottom - src0.y); }
            if (edge == 3) { p =  delta.y; q =  (edgeTop    - src0.y); }
            r = q / p;
            if (p == 0 && q < 0) return false;   // Don't draw line at all. (parallel line outside)

            if (p < 0)
            {
                if (r > t1) return false;         // Don't draw line at all.
                else if (r > t0) t0 = r;            // Line is clipped!
            }
            else if (p > 0)
            {
                if (r < t0) return false;      // Don't draw line at all.
                else if (r < t1) t1 = r;         // Line is clipped!
            }
        }

        clip0 = src0 + t0 * delta;
        clip1 = src0 + t1 * delta;

        return true;        // (clipped) line is drawn
    }

    void OnDrawGizmos()
    {
        Vector3 result = Vector3.zero;


        Gizmos.DrawLine(P0.position, P1.position);
        Gizmos.DrawLine(P2.position, P3.position);

        Vector2 clip1 = Vector2.zero;
        Vector2 clip2 = Vector2.zero;
        Vector2 clip3 = Vector2.zero;
        Vector2 clip4 = Vector2.zero;
        PackedLiangBarsky(-1, 1, -1, 1, new Vector2(P0.position.x, P0.position.z), new Vector2(P1.position.x, P1.position.z), ref clip1, ref clip2);
        gzmo.drawPoint(new Vector3(clip1.x, 0, clip1.y));
        gzmo.drawPoint(new Vector3(clip2.x, 0, clip2.y));

        PackedLiangBarsky(-1, 1, -1, 1, new Vector2(P0.position.x, P0.position.y), new Vector2(P1.position.x, P1.position.y), ref clip3, ref clip4);
        gzmo.drawPoint(new Vector3(clip3.x, clip3.y, 0));
        gzmo.drawPoint(new Vector3(clip4.x, clip4.y, 0));

        //PackedLiangBarsky(-1, 1, -1, 1, new Vector2(P0.position.y, P0.position.z), new Vector2(P1.position.y, P1.position.z), ref clip1, ref clip2);
        //gzmo.drawPoint(new Vector3(0, clip1.x, clip1.y));
        //gzmo.drawPoint(new Vector3(0, clip2.x, clip2.y));


        gzmo.drawPoint(Camera.position);


        Gizmos.DrawRay(Camera.position, Camera.forward * 5);
    }
}