1 // Created on: 2013-05-29
2 // Created by: Anton POLETAEV
3 // Copyright (c) 1999-2014 OPEN CASCADE SAS
5 // This file is part of Open CASCADE Technology software library.
7 // This library is free software; you can redistribute it and/or modify it under
8 // the terms of the GNU Lesser General Public License version 2.1 as published
9 // by the Free Software Foundation, with special exception defined in the file
10 // OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
11 // distribution for complete text of the license and disclaimer of any warranty.
13 // Alternatively, this file may be used under the terms of Open CASCADE
14 // commercial license or contractual agreement.
16 #ifndef _Graphic3d_Camera_HeaderFile
17 #define _Graphic3d_Camera_HeaderFile
19 #include <Graphic3d_CameraTile.hxx>
20 #include <Graphic3d_Mat4d.hxx>
21 #include <Graphic3d_Mat4.hxx>
22 #include <Graphic3d_Vec3.hxx>
23 #include <Graphic3d_WorldViewProjState.hxx>
24 #include <NCollection_Lerp.hxx>
29 #include <Standard_Macro.hxx>
30 #include <Standard_TypeDef.hxx>
32 #include <Bnd_Box.hxx>
34 //! Forward declaration
35 class Graphic3d_WorldViewProjState;
37 //! Camera class provides object-oriented approach to setting up projection
38 //! and orientation properties of 3D view.
39 class Graphic3d_Camera : public Standard_Transient
43 //! Template container for cached matrices or Real/ShortReal types.
44 template<typename Elem_t>
45 struct TransformMatrices
48 //! Default constructor.
49 TransformMatrices() : myIsOrientationValid (Standard_False), myIsProjectionValid (Standard_False) {}
51 //! Initialize orientation.
52 void InitOrientation()
54 myIsOrientationValid = Standard_True;
55 Orientation.InitIdentity();
58 //! Initialize projection.
61 myIsProjectionValid = Standard_True;
62 MProjection.InitIdentity();
63 LProjection.InitIdentity();
64 RProjection.InitIdentity();
67 //! Invalidate orientation.
68 void ResetOrientation() { myIsOrientationValid = Standard_False; }
70 //! Invalidate projection.
71 void ResetProjection() { myIsProjectionValid = Standard_False; }
73 //! Return true if Orientation was not invalidated.
74 Standard_Boolean IsOrientationValid() const { return myIsOrientationValid; }
76 //! Return true if Projection was not invalidated.
77 Standard_Boolean IsProjectionValid() const { return myIsProjectionValid; }
81 NCollection_Mat4<Elem_t> Orientation;
82 NCollection_Mat4<Elem_t> MProjection;
83 NCollection_Mat4<Elem_t> LProjection;
84 NCollection_Mat4<Elem_t> RProjection;
88 Standard_Boolean myIsOrientationValid;
89 Standard_Boolean myIsProjectionValid;
95 //! Enumerates supported monographic projections.
96 //! - Projection_Orthographic : orthographic projection.
97 //! - Projection_Perspective : perspective projection.
98 //! - Projection_Stereo : stereographic projection.
99 //! - Projection_MonoLeftEye : mono projection for stereo left eye.
100 //! - Projection_MonoRightEye : mono projection for stereo right eye.
103 Projection_Orthographic,
104 Projection_Perspective,
106 Projection_MonoLeftEye,
107 Projection_MonoRightEye
110 //! Enumerates approaches to define stereographic focus.
111 //! - FocusType_Absolute : focus is specified as absolute value.
112 //! - FocusType_Relative : focus is specified relative to
113 //! (as coefficient of) camera focal length.
120 //! Enumerates approaches to define Intraocular distance.
121 //! - IODType_Absolute : Intraocular distance is defined as absolute value.
122 //! - IODType_Relative : Intraocular distance is defined relative to
123 //! (as coefficient of) camera focal length.
132 //! Default constructor.
133 //! Initializes camera with the following properties:
134 //! Eye (0, 0, -2); Center (0, 0, 0); Up (0, 1, 0);
135 //! Type (Orthographic); FOVy (45); Scale (1000); IsStereo(false);
136 //! ZNear (0.001); ZFar (3000.0); Aspect(1);
137 //! ZFocus(1.0); ZFocusType(Relative); IOD(0.05); IODType(Relative)
138 Standard_EXPORT Graphic3d_Camera();
140 //! Copy constructor.
141 //! @param theOther [in] the camera to copy from.
142 Standard_EXPORT Graphic3d_Camera (const Handle(Graphic3d_Camera)& theOther);
144 //! Initialize mapping related parameters from other camera handle.
145 Standard_EXPORT void CopyMappingData (const Handle(Graphic3d_Camera)& theOtherCamera);
147 //! Initialize orientation related parameters from other camera handle.
148 Standard_EXPORT void CopyOrientationData (const Handle(Graphic3d_Camera)& theOtherCamera);
150 //! Copy properties of another camera.
151 //! @param theOther [in] the camera to copy from.
152 Standard_EXPORT void Copy (const Handle(Graphic3d_Camera)& theOther);
154 //! @name Public camera properties
157 //! Sets camera Eye position.
158 //! @param theEye [in] the location of camera's Eye.
159 Standard_EXPORT void SetEye (const gp_Pnt& theEye);
161 //! Get camera Eye position.
162 //! @return camera eye location.
163 const gp_Pnt& Eye() const
168 //! Sets Center of the camera.
169 //! @param theCenter [in] the point where the camera looks at.
170 Standard_EXPORT void SetCenter (const gp_Pnt& theCenter);
172 //! Get Center of the camera.
173 //! @return the point where the camera looks at.
174 const gp_Pnt& Center() const
179 //! Sets camera Up direction vector, orthogonal to camera direction.
180 //! @param theUp [in] the Up direction vector.
181 Standard_EXPORT void SetUp (const gp_Dir& theUp);
183 //! Orthogonalize up direction vector.
184 Standard_EXPORT void OrthogonalizeUp();
186 //! Return a copy of orthogonalized up direction vector.
187 Standard_EXPORT gp_Dir OrthogonalizedUp() const;
189 //! Get camera Up direction vector.
190 //! @return Camera's Up direction vector.
191 const gp_Dir& Up() const
196 //! Set camera axial scale.
197 //! @param theAxialScale [in] the axial scale vector.
198 Standard_EXPORT void SetAxialScale (const gp_XYZ& theAxialScale);
200 //! Get camera axial scale.
201 //! @return Camera's axial scale.
202 const gp_XYZ& AxialScale() const
207 //! Set distance of Eye from camera Center.
208 //! @param theDistance [in] the distance.
209 Standard_EXPORT void SetDistance (const Standard_Real theDistance);
211 //! Get distance of Eye from camera Center.
212 //! @return the distance.
213 Standard_EXPORT Standard_Real Distance() const;
215 //! Sets camera look direction.
216 //! @param theDir [in] the direction.
217 Standard_EXPORT void SetDirection (const gp_Dir& theDir);
219 //! Get camera look direction.
220 //! @return camera look direction.
221 Standard_EXPORT gp_Dir Direction() const;
223 //! Sets camera scale. For orthographic projection the scale factor
224 //! corresponds to parallel scale of view mapping (i.e. size
225 //! of viewport). For perspective camera scale is converted to
226 //! distance. The scale specifies equal size of the view projection in
227 //! both dimensions assuming that the aspect is 1.0. The projection height
228 //! and width are specified with the scale and correspondingly multiplied
230 //! @param theScale [in] the scale factor.
231 Standard_EXPORT void SetScale (const Standard_Real theScale);
233 //! Get camera scale.
234 //! @return camera scale factor.
235 Standard_EXPORT Standard_Real Scale() const;
237 //! Change camera projection type.
238 //! When switching to perspective projection from orthographic one,
239 //! the ZNear and ZFar are reset to default values (0.001, 3000.0)
240 //! if less than 0.0.
241 //! @param theProjectionType [in] the camera projection type.
242 Standard_EXPORT void SetProjectionType (const Projection theProjection);
244 //! @return camera projection type.
245 Projection ProjectionType() const
250 //! Check that the camera projection is orthographic.
251 //! @return boolean flag that indicates whether the camera's projection is
252 //! orthographic or not.
253 Standard_Boolean IsOrthographic() const
255 return (myProjType == Projection_Orthographic);
258 //! Check whether the camera projection is stereo.
259 //! Please note that stereo rendering is now implemented with support of
261 //! @return boolean flag indicating whether the stereographic L/R projection
263 Standard_Boolean IsStereo() const
265 return (myProjType == Projection_Stereo);
268 //! Set Field Of View (FOV) in y axis for perspective projection.
269 //! @param theFOVy [in] the FOV in degrees.
270 Standard_EXPORT void SetFOVy (const Standard_Real theFOVy);
272 //! Get Field Of View (FOV) in y axis.
273 //! @return the FOV value in degrees.
274 Standard_Real FOVy() const
279 //! Estimate Z-min and Z-max planes of projection volume to match the
280 //! displayed objects. The methods ensures that view volume will
281 //! be close by depth range to the displayed objects. Fitting assumes that
282 //! for orthogonal projection the view volume contains the displayed objects
283 //! completely. For zoomed perspective view, the view volume is adjusted such
284 //! that it contains the objects or their parts, located in front of the camera.
285 //! @param theScaleFactor [in] the scale factor for Z-range.
286 //! The range between Z-min, Z-max projection volume planes
287 //! evaluated by z fitting method will be scaled using this coefficient.
288 //! Program error exception is thrown if negative or zero value is passed.
289 //! @param theMinMax [in] applicative min max boundaries.
290 //! @param theScaleFactor [in] real graphical boundaries (not accounting infinite flag).
291 Standard_EXPORT bool ZFitAll (const Standard_Real theScaleFactor,
292 const Bnd_Box& theMinMax,
293 const Bnd_Box& theGraphicBB,
294 Standard_Real& theZNear,
295 Standard_Real& theZFar) const;
297 //! Change Z-min and Z-max planes of projection volume to match the displayed objects.
298 void ZFitAll (const Standard_Real theScaleFactor, const Bnd_Box& theMinMax, const Bnd_Box& theGraphicBB)
300 Standard_Real aZNear = 0.0, aZFar = 1.0;
301 ZFitAll (theScaleFactor, theMinMax, theGraphicBB, aZNear, aZFar);
302 SetZRange (aZNear, aZFar);
305 //! Change the Near and Far Z-clipping plane positions.
306 //! For orthographic projection, theZNear, theZFar can be negative or positive.
307 //! For perspective projection, only positive values are allowed.
308 //! Program error exception is raised if non-positive values are
309 //! specified for perspective projection or theZNear >= theZFar.
310 //! @param theZNear [in] the distance of the plane from the Eye.
311 //! @param theZFar [in] the distance of the plane from the Eye.
312 Standard_EXPORT void SetZRange (const Standard_Real theZNear, const Standard_Real theZFar);
314 //! Get the Near Z-clipping plane position.
315 //! @return the distance of the plane from the Eye.
316 Standard_Real ZNear() const
321 //! Get the Far Z-clipping plane position.
322 //! @return the distance of the plane from the Eye.
323 Standard_Real ZFar() const
328 //! Changes width / height display ratio.
329 //! @param theAspect [in] the display ratio.
330 Standard_EXPORT void SetAspect (const Standard_Real theAspect);
332 //! Get camera display ratio.
333 //! @return display ratio.
334 Standard_Real Aspect() const
339 //! Sets stereographic focus distance.
340 //! @param theType [in] the focus definition type. Focus can be defined
341 //! as absolute value or relatively to (as coefficient of) coefficient of
342 //! camera focal length.
343 //! @param theZFocus [in] the focus absolute value or coefficient depending
344 //! on the passed definition type.
345 Standard_EXPORT void SetZFocus (const FocusType theType, const Standard_Real theZFocus);
347 //! Get stereographic focus value.
348 //! @return absolute or relative stereographic focus value
349 //! depending on its definition type.
350 Standard_Real ZFocus() const
355 //! Get stereographic focus definition type.
356 //! @return definition type used for stereographic focus.
357 FocusType ZFocusType() const
362 //! Sets Intraocular distance.
363 //! @param theType [in] the IOD definition type. IOD can be defined as
364 //! absolute value or relatively to (as coefficient of) camera focal length.
365 //! @param theIOD [in] the Intraocular distance.
366 Standard_EXPORT void SetIOD (const IODType theType, const Standard_Real theIOD);
368 //! Get Intraocular distance value.
369 //! @return absolute or relative IOD value depending on its definition type.
370 Standard_Real IOD() const
375 //! Get Intraocular distance definition type.
376 //! @return definition type used for Intraocular distance.
377 IODType GetIODType() const
382 //! Get current tile.
383 const Graphic3d_CameraTile& Tile() const { return myTile; }
385 //! Sets the Tile defining the drawing sub-area within View.
386 //! Note that tile defining a region outside the view boundaries is also valid - use method Graphic3d_CameraTile::Cropped() to assign a cropped copy.
387 //! @param theTile tile definition
388 Standard_EXPORT void SetTile (const Graphic3d_CameraTile& theTile);
390 //! @name Basic camera operations
393 //! Transform orientation components of the camera:
394 //! Eye, Up and Center points.
395 //! @param theTrsf [in] the transformation to apply.
396 Standard_EXPORT void Transform (const gp_Trsf& theTrsf);
398 //! Calculate view plane size at center (target) point
399 //! and distance between ZFar and ZNear planes.
400 //! @return values in form of gp_Pnt (Width, Height, Depth).
401 gp_XYZ ViewDimensions() const
403 return ViewDimensions (Distance());
406 //! Calculate view plane size at center point with specified Z offset
407 //! and distance between ZFar and ZNear planes.
408 //! @param theZValue [in] the distance from the eye in eye-to-center direction
409 //! @return values in form of gp_Pnt (Width, Height, Depth).
410 Standard_EXPORT gp_XYZ ViewDimensions (const Standard_Real theZValue) const;
412 //! Calculate WCS frustum planes for the camera projection volume.
413 //! Frustum is a convex volume determined by six planes directing
415 //! The frustum planes are usually used as inputs for camera algorithms.
416 //! Thus, if any changes to projection matrix calculation are necessary,
417 //! the frustum planes calculation should be also touched.
418 //! @param theLeft [out] the frustum plane for left side of view.
419 //! @param theRight [out] the frustum plane for right side of view.
420 //! @param theBottom [out] the frustum plane for bottom side of view.
421 //! @param theTop [out] the frustum plane for top side of view.
422 //! @param theNear [out] the frustum plane for near side of view.
423 //! @param theFar [out] the frustum plane for far side of view.
424 Standard_EXPORT void Frustum (gp_Pln& theLeft,
429 gp_Pln& theFar) const;
431 //! @name Projection methods
434 //! Project point from world coordinate space to
435 //! normalized device coordinates (mapping).
436 //! @param thePnt [in] the 3D point in WCS.
437 //! @return mapped point in NDC.
438 Standard_EXPORT gp_Pnt Project (const gp_Pnt& thePnt) const;
440 //! Unproject point from normalized device coordinates
441 //! to world coordinate space.
442 //! @param thePnt [in] the NDC point.
443 //! @return 3D point in WCS.
444 Standard_EXPORT gp_Pnt UnProject (const gp_Pnt& thePnt) const;
446 //! Convert point from view coordinate space to
447 //! projection coordinate space.
448 //! @param thePnt [in] the point in VCS.
449 //! @return point in NDC.
450 Standard_EXPORT gp_Pnt ConvertView2Proj (const gp_Pnt& thePnt) const;
452 //! Convert point from projection coordinate space
453 //! to view coordinate space.
454 //! @param thePnt [in] the point in NDC.
455 //! @return point in VCS.
456 Standard_EXPORT gp_Pnt ConvertProj2View (const gp_Pnt& thePnt) const;
458 //! Convert point from world coordinate space to
459 //! view coordinate space.
460 //! @param thePnt [in] the 3D point in WCS.
461 //! @return point in VCS.
462 Standard_EXPORT gp_Pnt ConvertWorld2View (const gp_Pnt& thePnt) const;
464 //! Convert point from view coordinate space to
465 //! world coordinates.
466 //! @param thePnt [in] the 3D point in VCS.
467 //! @return point in WCS.
468 Standard_EXPORT gp_Pnt ConvertView2World (const gp_Pnt& thePnt) const;
470 //! @name Camera modification state
473 //! @return projection modification state of the camera.
474 const Graphic3d_WorldViewProjState& WorldViewProjState() const
476 return myWorldViewProjState;
480 //! Returns modification state of camera projection matrix
481 Standard_Size ProjectionState() const
483 return myWorldViewProjState.ProjectionState();
486 //! Returns modification state of camera world view transformation matrix.
487 Standard_Size WorldViewState() const
489 return myWorldViewProjState.WorldViewState();
492 //! @name Lazily-computed orientation and projection matrices derived from camera parameters
495 //! Get orientation matrix.
496 //! @return camera orientation matrix.
497 Standard_EXPORT const Graphic3d_Mat4d& OrientationMatrix() const;
499 //! Get orientation matrix of Standard_ShortReal precision.
500 //! @return camera orientation matrix.
501 Standard_EXPORT const Graphic3d_Mat4& OrientationMatrixF() const;
503 //! Get monographic or middle point projection matrix used for monographic
504 //! rendering and for point projection / unprojection.
505 //! @return monographic projection matrix.
506 Standard_EXPORT const Graphic3d_Mat4d& ProjectionMatrix() const;
508 //! Get monographic or middle point projection matrix of Standard_ShortReal precision used for monographic
509 //! rendering and for point projection / unprojection.
510 //! @return monographic projection matrix.
511 Standard_EXPORT const Graphic3d_Mat4& ProjectionMatrixF() const;
513 //! @return stereographic matrix computed for left eye. Please note
514 //! that this method is used for rendering for <i>Projection_Stereo</i>.
515 Standard_EXPORT const Graphic3d_Mat4d& ProjectionStereoLeft() const;
517 //! @return stereographic matrix of Standard_ShortReal precision computed for left eye.
518 //! Please note that this method is used for rendering for <i>Projection_Stereo</i>.
519 Standard_EXPORT const Graphic3d_Mat4& ProjectionStereoLeftF() const;
521 //! @return stereographic matrix computed for right eye. Please note
522 //! that this method is used for rendering for <i>Projection_Stereo</i>.
523 Standard_EXPORT const Graphic3d_Mat4d& ProjectionStereoRight() const;
525 //! @return stereographic matrix of Standard_ShortReal precision computed for right eye.
526 //! Please note that this method is used for rendering for <i>Projection_Stereo</i>.
527 Standard_EXPORT const Graphic3d_Mat4& ProjectionStereoRightF() const;
529 //! Invalidate state of projection matrix.
530 //! The matrix will be updated on request.
531 Standard_EXPORT void InvalidateProjection();
533 //! Invalidate orientation matrix.
534 //! The matrix will be updated on request.
535 Standard_EXPORT void InvalidateOrientation();
537 //! @name Managing projection and orientation cache
540 //! Compute projection matrices.
541 //! @param theMatrices [in] the matrices data container.
542 template <typename Elem_t>
544 TransformMatrices<Elem_t>& UpdateProjection (TransformMatrices<Elem_t>& theMatrices) const;
546 //! Compute orientation matrix.
547 //! @param theMatrices [in] the matrices data container.
548 template <typename Elem_t>
550 TransformMatrices<Elem_t>& UpdateOrientation (TransformMatrices<Elem_t>& theMatrices) const;
554 //! Compose orthographic projection matrix for
555 //! the passed camera volume mapping.
556 //! @param theLeft [in] the left mapping (clipping) coordinate.
557 //! @param theRight [in] the right mapping (clipping) coordinate.
558 //! @param theBottom [in] the bottom mapping (clipping) coordinate.
559 //! @param theTop [in] the top mapping (clipping) coordinate.
560 //! @param theNear [in] the near mapping (clipping) coordinate.
561 //! @param theFar [in] the far mapping (clipping) coordinate.
562 //! @param theOutMx [out] the projection matrix.
563 template <typename Elem_t>
565 OrthoProj (const Elem_t theLeft,
566 const Elem_t theRight,
567 const Elem_t theBottom,
569 const Elem_t theNear,
571 NCollection_Mat4<Elem_t>& theOutMx);
573 //! Compose perspective projection matrix for
574 //! the passed camera volume mapping.
575 //! @param theLeft [in] the left mapping (clipping) coordinate.
576 //! @param theRight [in] the right mapping (clipping) coordinate.
577 //! @param theBottom [in] the bottom mapping (clipping) coordinate.
578 //! @param theTop [in] the top mapping (clipping) coordinate.
579 //! @param theNear [in] the near mapping (clipping) coordinate.
580 //! @param theFar [in] the far mapping (clipping) coordinate.
581 //! @param theOutMx [out] the projection matrix.
582 template <typename Elem_t>
584 PerspectiveProj (const Elem_t theLeft,
585 const Elem_t theRight,
586 const Elem_t theBottom,
588 const Elem_t theNear,
590 NCollection_Mat4<Elem_t>& theOutMx);
592 //! Compose projection matrix for L/R stereo eyes.
593 //! @param theLeft [in] the left mapping (clipping) coordinate.
594 //! @param theRight [in] the right mapping (clipping) coordinate.
595 //! @param theBottom [in] the bottom mapping (clipping) coordinate.
596 //! @param theTop [in] the top mapping (clipping) coordinate.
597 //! @param theNear [in] the near mapping (clipping) coordinate.
598 //! @param theFar [in] the far mapping (clipping) coordinate.
599 //! @param theIOD [in] the Intraocular distance.
600 //! @param theZFocus [in] the z coordinate of off-axis
601 //! projection plane with zero parallax.
602 //! @param theIsLeft [in] boolean flag to choose between L/R eyes.
603 //! @param theOutMx [out] the projection matrix.
604 template <typename Elem_t>
606 StereoEyeProj (const Elem_t theLeft,
607 const Elem_t theRight,
608 const Elem_t theBottom,
610 const Elem_t theNear,
613 const Elem_t theZFocus,
614 const Standard_Boolean theIsLeft,
615 NCollection_Mat4<Elem_t>& theOutMx);
617 //! Construct "look at" orientation transformation.
618 //! Reference point differs for perspective and ortho modes
619 //! (made for compatibility, to be improved..).
620 //! @param theEye [in] the eye coordinates in 3D space.
621 //! @param theLookAt [in] the point the camera looks at.
622 //! @param theUpDir [in] the up direction vector.
623 //! @param theAxialScale [in] the axial scale vector.
624 //! @param theOutMx [in/out] the orientation matrix.
625 template <typename Elem_t>
627 LookOrientation (const NCollection_Vec3<Elem_t>& theEye,
628 const NCollection_Vec3<Elem_t>& theLookAt,
629 const NCollection_Vec3<Elem_t>& theUpDir,
630 const NCollection_Vec3<Elem_t>& theAxialScale,
631 NCollection_Mat4<Elem_t>& theOutMx);
635 gp_Dir myUp; //!< Camera up direction vector.
636 gp_Pnt myEye; //!< Camera eye position.
637 gp_Pnt myCenter; //!< Camera center.
639 gp_XYZ myAxialScale; //!< World axial scale.
641 Projection myProjType; //!< Projection type used for rendering.
642 Standard_Real myFOVy; //!< Field Of View in y axis.
643 Standard_Real myFOVyTan; //!< Field Of View as Tan(DTR_HALF * myFOVy)
644 Standard_Real myZNear; //!< Distance to near clipping plane.
645 Standard_Real myZFar; //!< Distance to far clipping plane.
646 Standard_Real myAspect; //!< Width to height display ratio.
648 Standard_Real myScale; //!< Specifies parallel scale for orthographic projection.
649 Standard_Real myZFocus; //!< Stereographic focus value.
650 FocusType myZFocusType; //!< Stereographic focus definition type.
652 Standard_Real myIOD; //!< Intraocular distance value.
653 IODType myIODType; //!< Intraocular distance definition type.
655 Graphic3d_CameraTile myTile;//!< Tile defining sub-area for drawing
657 mutable TransformMatrices<Standard_Real> myMatricesD;
658 mutable TransformMatrices<Standard_ShortReal> myMatricesF;
660 mutable Graphic3d_WorldViewProjState myWorldViewProjState;
664 DEFINE_STANDARD_RTTIEXT(Graphic3d_Camera,Standard_Transient)
667 DEFINE_STANDARD_HANDLE (Graphic3d_Camera, Standard_Transient)
669 //! Linear interpolation tool for camera orientation and position.
670 //! This tool interpolates camera parameters scale, eye, center, rotation (up and direction vectors) independently.
672 //! Eye/Center interpolation is performed through defining an anchor point in-between Center and Eye.
673 //! The anchor position is defined as point near to the camera point which has smaller translation part.
674 //! The main idea is to keep the distance between Center and Eye
675 //! (which will change if Center and Eye translation will be interpolated independently).
677 //! - When both Center and Eye are moved at the same vector -> both will be just translated by straight line
678 //! - When Center is not moved -> camera Eye will move around Center through arc
679 //! - When Eye is not moved -> camera Center will move around Eye through arc
680 //! - When both Center and Eye are move by different vectors -> transformation will be something in between,
681 //! and will try interpolate linearly the distance between Center and Eye.
683 //! This transformation might be not in line with user expectations.
684 //! In this case, application might define intermediate camera positions for interpolation
685 //! or implement own interpolation logic.
687 Standard_EXPORT void NCollection_Lerp<Handle(Graphic3d_Camera)>::Interpolate (const double theT,
688 Handle(Graphic3d_Camera)& theResult) const;
689 typedef NCollection_Lerp<Handle(Graphic3d_Camera)> Graphic3d_CameraLerp;