1+ using SharpDX ;
2+ using System ;
3+ #if ! NETFX_CORE
4+ namespace HelixToolkit . Wpf . SharpDX
5+ #else
6+ #if CORE
7+ namespace HelixToolkit . SharpDX . Core
8+ #else
9+ namespace HelixToolkit . UWP
10+ #endif
11+ #endif
12+ {
13+ using Cameras ;
14+ public static class CameraCoreExtensions
15+ {
16+ public static BoundingFrustum CreateFrustum ( this CameraCore camera , float aspectRatio )
17+ {
18+ return new BoundingFrustum ( camera . CreateViewMatrix ( ) * camera . CreateProjectionMatrix ( aspectRatio ) ) ;
19+ }
20+
21+ // Returns whether or not the given point is the outermost point in the given direction among all points of the bounds
22+ private static bool IsOutermostPointInDirection ( int pointIndex , ref Vector3 direction , Vector3 [ ] corners )
23+ {
24+ Vector3 point = corners [ pointIndex ] ;
25+ for ( int i = 0 ; i < corners . Length ; i ++ )
26+ {
27+ if ( i != pointIndex && Vector3 . Dot ( direction , corners [ i ] - point ) > 0 )
28+ return false ;
29+ }
30+
31+ return true ;
32+ }
33+
34+ // Credit: http://wiki.unity3d.com/index.php/3d_Math_functions
35+ // Returns the edge points of the closest line segment between 2 lines
36+ private static void FindClosestPointsOnTwoLines ( ref Ray line1 , ref Ray line2 , out Vector3 closestPointLine1 , out Vector3 closestPointLine2 )
37+ {
38+ Vector3 line1Direction = line1 . Direction ;
39+ Vector3 line2Direction = line2 . Direction ;
40+
41+ float a = Vector3 . Dot ( line1Direction , line1Direction ) ;
42+ float b = Vector3 . Dot ( line1Direction , line2Direction ) ;
43+ float e = Vector3 . Dot ( line2Direction , line2Direction ) ;
44+
45+ float d = a * e - b * b ;
46+
47+ Vector3 r = line1 . Position - line2 . Position ;
48+ float c = Vector3 . Dot ( line1Direction , r ) ;
49+ float f = Vector3 . Dot ( line2Direction , r ) ;
50+
51+ float s = ( b * f - c * e ) / d ;
52+ float t = ( a * f - c * b ) / d ;
53+
54+ closestPointLine1 = line1 . Position + line1Direction * s ;
55+ closestPointLine2 = line2 . Position + line2Direction * t ;
56+ }
57+ /// <summary>
58+ /// Ref: https://github.com/yasirkula/UnityRuntimePreviewGenerator/blob/7a3b44b07949f712010b680b9f2c499e5aa2ebc1/Plugins/RuntimePreviewGenerator/RuntimePreviewGenerator.cs#L347
59+ /// </summary>
60+ /// <param name="camera"></param>
61+ /// <param name="aspectRatio"></param>
62+ /// <param name="boundingBox"></param>
63+ /// <param name="position"></param>
64+ /// <param name="lookDir"></param>
65+ /// <param name="upDir"></param>
66+ public static void ZoomExtents ( this PerspectiveCameraCore camera , float aspectRatio , BoundingBox boundingBox , out Vector3 position , out Vector3 lookDir , out Vector3 upDir )
67+ {
68+ var cameraDir = Vector3 . Normalize ( camera . LookDirection ) ;
69+ var cameraUp = Vector3 . Normalize ( camera . UpDirection ) ;
70+ var cameraRight = Vector3 . Cross ( cameraDir , cameraUp ) ;
71+ cameraUp = Vector3 . Cross ( cameraRight , cameraDir ) ;
72+
73+ var corners = boundingBox . GetCorners ( ) ;
74+
75+ var frustum = camera . CreateFrustum ( aspectRatio ) ;
76+ var leftNormal = - frustum . Left . Normal ;
77+ var rightNormal = - frustum . Right . Normal ;
78+ var topNormal = - frustum . Top . Normal ;
79+ var bottomNormal = - frustum . Bottom . Normal ;
80+
81+ int leftMostPoint = - 1 , rightMostPoint = - 1 , topMostPoint = - 1 , bottomMostPoint = - 1 ;
82+ for ( int i = 0 ; i < corners . Length ; i ++ )
83+ {
84+ if ( leftMostPoint < 0 && IsOutermostPointInDirection ( i , ref leftNormal , corners ) )
85+ {
86+ leftMostPoint = i ;
87+ }
88+ if ( rightMostPoint < 0 && IsOutermostPointInDirection ( i , ref rightNormal , corners ) )
89+ {
90+ rightMostPoint = i ;
91+ }
92+ if ( topMostPoint < 0 && IsOutermostPointInDirection ( i , ref topNormal , corners ) )
93+ {
94+ topMostPoint = i ;
95+ }
96+ if ( bottomMostPoint < 0 && IsOutermostPointInDirection ( i , ref bottomNormal , corners ) )
97+ {
98+ bottomMostPoint = i ;
99+ }
100+ }
101+
102+ var plane1 = new Plane ( corners [ leftMostPoint ] , leftNormal ) ;
103+ var plane2 = new Plane ( corners [ rightMostPoint ] , rightNormal ) ;
104+ PlaneExtensions . PlaneIntersectsPlane ( ref plane1 , ref plane2 , out var horizontalIntersection ) ;
105+ plane1 = new Plane ( corners [ topMostPoint ] , topNormal ) ;
106+ plane2 = new Plane ( corners [ bottomMostPoint ] , bottomNormal ) ;
107+ PlaneExtensions . PlaneIntersectsPlane ( ref plane1 , ref plane2 , out var verticalIntersection ) ;
108+ FindClosestPointsOnTwoLines ( ref horizontalIntersection , ref verticalIntersection , out var closestPointLine1 , out var closestPointLine2 ) ;
109+ position = Vector3 . Dot ( closestPointLine1 - closestPointLine2 , cameraDir ) < 0 ? closestPointLine1 : closestPointLine2 ;
110+ upDir = cameraUp ;
111+ var boundPlane = new Plane ( boundingBox . Center , cameraDir ) ;
112+ var lookRay = new Ray ( position , cameraDir ) ;
113+ boundPlane . Intersects ( ref lookRay , out float dist ) ;
114+ lookDir = cameraDir * dist ;
115+ }
116+ /// <summary>
117+ /// Ref: https://github.com/yasirkula/UnityRuntimePreviewGenerator/blob/7a3b44b07949f712010b680b9f2c499e5aa2ebc1/Plugins/RuntimePreviewGenerator/RuntimePreviewGenerator.cs#L347
118+ /// </summary>
119+ /// <param name="camera"></param>
120+ /// <param name="aspectRatio"></param>
121+ /// <param name="boundingBox"></param>
122+ /// <param name="position"></param>
123+ /// <param name="lookDir"></param>
124+ /// <param name="upDir"></param>
125+ /// <param name="width"></param>
126+ public static void ZoomExtents ( this OrthographicCameraCore camera , float aspectRatio , BoundingBox boundingBox , out Vector3 position , out Vector3 lookDir , out Vector3 upDir , out float width )
127+ {
128+ float minX = float . PositiveInfinity , minY = float . PositiveInfinity , maxX = float . NegativeInfinity , maxY = float . NegativeInfinity ;
129+ var corners = boundingBox . GetCorners ( ) ;
130+ var view = camera . CreateViewMatrix ( ) ;
131+ foreach ( var p in corners )
132+ {
133+ var local = Vector3 . TransformCoordinate ( p , view ) ;
134+ minX = Math . Min ( minX , local . X ) ;
135+ minY = Math . Min ( minY , local . Y ) ;
136+ maxX = Math . Max ( maxX , local . X ) ;
137+ maxY = Math . Max ( maxY , local . Y ) ;
138+ }
139+ width = aspectRatio > 1 ? Math . Max ( ( maxX - minX ) , ( maxY - minY ) * aspectRatio ) : Math . Max ( ( maxX - minX ) / aspectRatio , maxY - minY ) ;
140+ position = boundingBox . Center - camera . LookDirection . Normalized ( ) * width ;
141+ lookDir = camera . LookDirection . Normalized ( ) * width ;
142+ upDir = camera . UpDirection ;
143+ }
144+ }
145+ }
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