ClassiCube/Selections/SelectionBoxComparer.cs
2015-06-27 12:11:47 +10:00

42 lines
1.8 KiB
C#

using System;
using System.Collections.Generic;
using OpenTK;
namespace ClassicalSharp.Selections {
internal class SelectionBoxComparer : IComparer<SelectionBox> {
public Vector3 pos;
public int Compare( SelectionBox a, SelectionBox b ) {
float minDistA = float.PositiveInfinity, minDistB = float.PositiveInfinity;
float maxDistA = float.NegativeInfinity, maxDistB = float.NegativeInfinity;
Intersect( a, pos, ref minDistA, ref maxDistA );
Intersect( b, pos, ref minDistB, ref maxDistB );
// Reversed comparison order because we need to render back to front for alpha blending.
return minDistA == minDistB ? maxDistB.CompareTo( maxDistA ) : minDistB.CompareTo( minDistA );
}
void Intersect( SelectionBox box, Vector3 origin, ref float closest, ref float furthest ) {
Vector3I min = box.Min;
Vector3I max = box.Max;
// Bottom corners
UpdateDist( pos, min.X, min.Y, min.Z, ref closest, ref furthest );
UpdateDist( pos, max.X, min.Y, min.Z, ref closest, ref furthest );
UpdateDist( pos, max.X, min.Y, max.Z, ref closest, ref furthest );
UpdateDist( pos, min.X, min.Y, max.Z, ref closest, ref furthest );
// top corners
UpdateDist( pos, min.X, max.Y, min.Z, ref closest, ref furthest );
UpdateDist( pos, max.X, max.Y, min.Z, ref closest, ref furthest );
UpdateDist( pos, max.X, max.Y, max.Z, ref closest, ref furthest );
UpdateDist( pos, min.X, max.Y, max.Z, ref closest, ref furthest );
}
static void UpdateDist( Vector3 p, float x2, float y2, float z2,
ref float closest, ref float furthest ) {
float dist = Utils.DistanceSquared( p.X, p.Y, p.Z, x2, y2, z2 );
if( dist < closest ) closest = dist;
if( dist > furthest ) furthest = dist;
}
}
}