OniSplit/Akira/PolygonUtils.cs

using System;
using System.Collections.Generic;

namespace Oni.Akira
{
    internal class PolygonUtils
    {
        public static List<Vector3> ClipToPlane(List<Vector3> points, Plane plane)
        {
            var signs = new int[points.Count];
            var negativeCount = 0;
            var positiveCount = 0;
            var start = 0;

            for (int i = 0; i < points.Count; i++)
            {
                signs[i] = RelativePosition(points[i], plane);

                if (signs[i] >= 0)
                    positiveCount++;

                if (signs[i] <= 0)
                    negativeCount++;
            }

            if (negativeCount == points.Count)
                return null;

            if (positiveCount == points.Count)
                return points;

            var newPoints = new List<Vector3>();

            for (int i = 0; i < points.Count; i++)
            {
                int i0 = (i + start) % points.Count;
                int i1 = (i + start + 1) % points.Count;

                int s0 = signs[i0];
                int s1 = signs[i1];

                if (s0 >= 0)
                {
                    newPoints.Add(points[i0]);

                    if (s0 > 0 && s1 < 0)
                        newPoints.Add(Intersect(points[i0], points[i1], plane));
                }
                else
                {
                    if (s0 < 0 && s1 > 0)
                        newPoints.Add(Intersect(points[i1], points[i0], plane));
                }
            }

            return newPoints;
        }

        private static Vector3 Intersect(Vector3 p0, Vector3 p1, Plane plane)
        {
            Vector3 dir = p1 - p0;

            float dND = plane.DotNormal(dir);

            if (Math.Abs(dND) < 1e-05f)
                throw new InvalidOperationException();

            float distance = (-plane.D - plane.DotNormal(p0)) / dND;

            if (distance < 0.0f)
            {
                if (distance < -1e-05f)
                    throw new InvalidOperationException();

                return p0;
            }
            else
            {
                return p0 + dir * distance;
            }
        }

        private static int RelativePosition(Vector3 point, Plane plane)
        {
            float pos = plane.DotCoordinate(point);

            if (pos < -1e-05f)
                return -1;
            else if (pos > 1e-05f)
                return 1;
            else
                return 0;
        }
    }
}
Revision:	1114
Committed:	Wed Jan 22 14:08:57 2020 UTC (5 years, 8 months ago) by iritscen
File size:	2601 byte(s)
Log Message:	Adding OniSplit source code (v0.9.99.0). Many thanks to Neo for all his work over the years.
#	Content
1	using System;
2	using System.Collections.Generic;
3
4	namespace Oni.Akira
5	{
6	internal class PolygonUtils
7	{
8	public static List<Vector3> ClipToPlane(List<Vector3> points, Plane plane)
9	{
10	var signs = new int[points.Count];
11	var negativeCount = 0;
12	var positiveCount = 0;
13	var start = 0;
14
15	for (int i = 0; i < points.Count; i++)
16	{
17	signs[i] = RelativePosition(points[i], plane);
18
19	if (signs[i] >= 0)
20	positiveCount++;
21
22	if (signs[i] <= 0)
23	negativeCount++;
24	}
25
26	if (negativeCount == points.Count)
27	return null;
28
29	if (positiveCount == points.Count)
30	return points;
31
32	var newPoints = new List<Vector3>();
33
34	for (int i = 0; i < points.Count; i++)
35	{
36	int i0 = (i + start) % points.Count;
37	int i1 = (i + start + 1) % points.Count;
38
39	int s0 = signs[i0];
40	int s1 = signs[i1];
41
42	if (s0 >= 0)
43	{
44	newPoints.Add(points[i0]);
45
46	if (s0 > 0 && s1 < 0)
47	newPoints.Add(Intersect(points[i0], points[i1], plane));
48	}
49	else
50	{
51	if (s0 < 0 && s1 > 0)
52	newPoints.Add(Intersect(points[i1], points[i0], plane));
53	}
54	}
55
56	return newPoints;
57	}
58
59	private static Vector3 Intersect(Vector3 p0, Vector3 p1, Plane plane)
60	{
61	Vector3 dir = p1 - p0;
62
63	float dND = plane.DotNormal(dir);
64
65	if (Math.Abs(dND) < 1e-05f)
66	throw new InvalidOperationException();
67
68	float distance = (-plane.D - plane.DotNormal(p0)) / dND;
69
70	if (distance < 0.0f)
71	{
72	if (distance < -1e-05f)
73	throw new InvalidOperationException();
74
75	return p0;
76	}
77	else
78	{
79	return p0 + dir * distance;
80	}
81	}
82
83	private static int RelativePosition(Vector3 point, Plane plane)
84	{
85	float pos = plane.DotCoordinate(point);
86
87	if (pos < -1e-05f)
88	return -1;
89	else if (pos > 1e-05f)
90	return 1;
91	else
92	return 0;
93	}
94	}
95	}