60 lines
2.0 KiB
C#
60 lines
2.0 KiB
C#
|
using System.Collections.Generic;
|
||
|
|
using Unity.Mathematics;
|
||
|
|
|
||
|
|
namespace UnityEngine.U2D.Animation
|
||
|
|
{
|
||
|
|
internal static class MeshUtilities
|
||
|
|
{
|
||
|
|
/// <summary>
|
||
|
|
/// Get the outline edges from a set of indices.
|
||
|
|
/// This method expects the index array to be laid out with one triangle for every 3 indices.
|
||
|
|
/// E.g. triangle 0: index 0 - 2, triangle 1: index 3 - 5, etc.
|
||
|
|
/// </summary>
|
||
|
|
public static int2[] GetOutlineEdges(in int[] indices)
|
||
|
|
{
|
||
|
|
var edges = new Dictionary<int, int3>(indices.Length / 3);
|
||
|
|
|
||
|
|
for (var i = 0; i < indices.Length; i += 3)
|
||
|
|
{
|
||
|
|
var i0 = indices[i];
|
||
|
|
var i1 = indices[i + 1];
|
||
|
|
var i2 = indices[i + 2];
|
||
|
|
|
||
|
|
var edge0 = new int2(i0, i1);
|
||
|
|
var edge1 = new int2(i1, i2);
|
||
|
|
var edge2 = new int2(i2, i0);
|
||
|
|
|
||
|
|
AddToEdgeMap(edge0, ref edges);
|
||
|
|
AddToEdgeMap(edge1, ref edges);
|
||
|
|
AddToEdgeMap(edge2, ref edges);
|
||
|
|
}
|
||
|
|
|
||
|
|
var outlineEdges = new List<int2>(edges.Count);
|
||
|
|
foreach(var edgePair in edges)
|
||
|
|
{
|
||
|
|
// If an edge is only used in one triangle, it is an outline edge.
|
||
|
|
if (edgePair.Value.z == 1)
|
||
|
|
outlineEdges.Add(edgePair.Value.xy);
|
||
|
|
}
|
||
|
|
|
||
|
|
return outlineEdges.ToArray();
|
||
|
|
}
|
||
|
|
|
||
|
|
static void AddToEdgeMap(int2 edge, ref Dictionary<int, int3> edgeMap)
|
||
|
|
{
|
||
|
|
var tmpEdge = math.min(edge.x, edge.y) == edge.x ? edge.xy : edge.yx;
|
||
|
|
var hashCode = tmpEdge.GetHashCode();
|
||
|
|
|
||
|
|
// We store the hashCode as key, so that we can do less GetHashCode-calls.
|
||
|
|
// Then we store the count the int3s z-value.
|
||
|
|
if (!edgeMap.ContainsKey(hashCode))
|
||
|
|
edgeMap.Add(hashCode, new int3(edge, 1));
|
||
|
|
else
|
||
|
|
{
|
||
|
|
var val = edgeMap[hashCode];
|
||
|
|
val.z++;
|
||
|
|
edgeMap[hashCode] = val;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|