# Lens

from pandac.PandaModules import Lens

Class : Lens
Description : A base class for any number of different kinds of lenses, linear and otherwise. Presently, this includes perspective and orthographic lenses.
A Lens object is the main part of a Camera node (defined in sgraph), which defines the fundamental interface to point-of-view for rendering. Lenses are also used in other contexts, however; for instance, a Spotlight is also defined using a lens.

## Inheritance:

Lens: TypedWritableReferenceCount
TypedWritableReferenceCount: TypedWritable ReferenceCount
TypedWritable: TypedObject
TypedObject:
ReferenceCount:

## Methods of Lens:

clear
clearKeystone
clearViewMat
extrude
extrudeVec
getAspectRatio
getChangeEvent
getClassType
getConvergenceDistance
getCoordinateSystem
getDefaultFar
getDefaultNear
getFar
getFilmMat
getFilmMatInv
getFilmOffset
getFilmSize
getFocalLength
getFov
getHfov
getInterocularDistance
getKeystone
getLensMat
getLensMatInv
getMinFov
getNear
getNodalPoint
getProjectionMat
getProjectionMatInv
getUpVector
getVfov
getViewHpr
getViewMat
getViewVector
isLinear
isOrthographic
isPerspective
makeBounds
makeCopy
makeGeometry
output
project
recomputeAll
setAspectRatio
setChangeEvent
setConvergenceDistance
setCoordinateSystem
setFar
setFilmOffset
setFilmSize
setFocalLength
setFov
setFrustumFromCorners
setInterocularDistance
setKeystone
setMinFov
setNear
setNearFar
setViewHpr
setViewMat
setViewVector
write

## Methods of TypedWritableReferenceCount:

getClassType

## Methods of TypedWritable:

getClassType

## Methods of TypedObject:

getClassType
getType
getTypeIndex
isExactType
isOfType

## Methods of ReferenceCount:

getClassType
getRefCount
ref
testRefCountIntegrity
testRefCountNonzero
unref

## Constants in Lens:

SCMono | (StereoChannel)
SCLeft | (StereoChannel)
SCRight | (StereoChannel)
SCStereo | (StereoChannel)
FCRoll | (FromCorners)
FCCameraPlane | (FromCorners)
FCOffAxis | (FromCorners)
FCAspectRatio | (FromCorners)
FCShear | (FromCorners)
FCKeystone | (FromCorners)

clear void Lens::clear(void); Description: Resets all lens parameters to their initial default settings.

clearKeystone void Lens::clear_keystone(void); Description: Disables the lens keystone correction.

clearViewMat void Lens::clear_view_mat(void); Description: Resets the lens transform to identity.

extrude bool Lens::extrude(LPoint2f const &point2d, LPoint3f &near_point, LPoint3f &far_point) const; Filename: lens.I Created by: drose (29Nov01) PANDA 3D SOFTWARE Copyright (c) 2001 - 2004, Disney Enterprises, Inc. All rights reserved All use of this software is subject to the terms of the Panda 3d Software license. You should have received a copy of this license along with this source code; you will also find a current copy of the license at http://etc.cmu.edu/panda3d/docs/license/ . To contact the maintainers of this program write to panda3d-general@lists.sourceforge.net . Description: Given a 2-d point in the range (-1,1) in both dimensions, where (0,0) is the center of the lens and (-1,-1) is the lower-left corner, compute the corresponding vector in space that maps to this point, if such a vector can be determined. The vector is returned by indicating the points on the near plane and far plane that both map to the indicated 2-d point. Returns true if the vector is defined, or false otherwise. The z coordinate of the 2-d point is ignored.

extrudeVec bool Lens::extrude_vec(LPoint2f const &point2d, LVector3f &vec3d) const; Description: Given a 2-d point in the range (-1,1) in both dimensions, where (0,0) is the center of the lens and (-1,-1) is the lower-left corner, compute the vector that corresponds to the view direction. This will be parallel to the normal on the surface (the far plane) corresponding to the lens shape at this point. See the comment block on Lens::extrude_vec_impl() for a more in-depth comment on the meaning of this vector. Returns true if the vector is defined, or false otherwise. The z coordinate of the 2-d point is ignored.

getAspectRatio float Lens::get_aspect_ratio(void) const; Description: Returns the aspect ratio of the Lens. This is determined based on the indicated film size; see set_film_size().

getChangeEvent string const &Lens::get_change_event(void) const; Description: Returns the name of the event that will be generated whenever any properties of this particular Lens have changed.

getClassType static TypeHandle Lens::get_class_type(void); Undocumented function.

getConvergenceDistance float Lens::get_convergence_distance(void) const; Description: See set_convergence_distance().

getCoordinateSystem CoordinateSystem Lens::get_coordinate_system(void) const; Description: Returns the coordinate system that all 3-d computations are performed within for this Lens. Normally, this is CS_default.

getDefaultFar static float Lens::get_default_far(void); Description: Returns the default far plane distance that will be assigned to each newly-created lens. This is read from the Configrc file.

getDefaultNear static float Lens::get_default_near(void); Description: Returns the default near plane distance that will be assigned to each newly-created lens. This is read from the Configrc file.

getFar float Lens::get_far(void) const; Description: Returns the position of the far plane (or cylinder, sphere, whatever).

getFilmMat LMatrix4f const &Lens::get_film_mat(void) const; Description: Returns the matrix that transforms from a point behind the lens to a point on the film.

getFilmMatInv LMatrix4f const &Lens::get_film_mat_inv(void) const; Description: Returns the matrix that transforms from a point on the film to a point behind the lens.

getFilmOffset LVector2f const &Lens::get_film_offset(void) const; Description: Returns the horizontal and vertical offset amounts of this Lens. See set_film_offset().

getFilmSize LVecBase2f const &Lens::get_film_size(void) const; Description: Returns the horizontal and vertical film size of the virtual film. See set_film_size().

getFocalLength float Lens::get_focal_length(void) const; Description: Returns the focal length of the lens. This may have been set explicitly by a previous call to set_focal_length(), or it may be computed based on the lens' fov and film_size. For certain kinds of lenses, the focal length has no meaning.

getFov LVecBase2f const &Lens::get_fov(void) const; Description: Returns the horizontal and vertical film size of the virtual film. See set_fov().

getHfov float Lens::get_hfov(void) const; Description: Returns the horizontal component of fov only. See get_fov().

getInterocularDistance float Lens::get_interocular_distance(void) const; Description: See set_interocular_distance().

getKeystone LVecBase2f const &Lens::get_keystone(void) const; Description: Returns the keystone correction specified for the lens.

getLensMat LMatrix4f const &Lens::get_lens_mat(void) const; Description: Returns the matrix that transforms from a point in front of the lens to a point in space.

getLensMatInv LMatrix4f const &Lens::get_lens_mat_inv(void) const; Description: Returns the matrix that transforms from a point in space to a point in front of the lens.

getMinFov float Lens::get_min_fov(void) const; Description: Returns the field of view of the narrowest dimension of the window. See set_min_fov().

getNear float Lens::get_near(void) const; Description: Returns the position of the near plane (or cylinder, sphere, whatever).

getNodalPoint LPoint3f Lens::get_nodal_point(void) const; Description: Returns the center point of the lens: the point from which the lens is viewing.

getProjectionMat LMatrix4f const &Lens::get_projection_mat(Lens::StereoChannel channel = (SC_mono)) const; Description: Returns the complete transformation matrix from a 3-d point in space to a point on the film, if such a matrix exists, or the identity matrix if the lens is nonlinear.

getProjectionMatInv LMatrix4f const &Lens::get_projection_mat_inv(Lens::StereoChannel channel = (SC_mono)) const; Description: Returns the matrix that transforms from a 2-d point on the film to a 3-d vector in space, if such a matrix exists.

getUpVector LVector3f const &Lens::get_up_vector(void) const; Description: Returns the axis perpendicular to the camera's view vector that indicates the "up" direction.

getVfov float Lens::get_vfov(void) const; Description: Returns the vertical component of fov only. See get_fov().

getViewHpr LVecBase3f const &Lens::get_view_hpr(void) const; Description: Returns the direction in which the lens is facing.

getViewMat LMatrix4f const &Lens::get_view_mat(void) const; Description: Returns the direction in which the lens is facing.

getViewVector LVector3f const &Lens::get_view_vector(void) const; Description: Returns the axis along which the lens is facing.

isLinear virtual bool Lens::is_linear(void) const; Description: Returns true if the lens represents a linear projection (e.g. PerspectiveLens, OrthographicLens), and therefore there is a valid matrix returned by get_projection_mat(), or false otherwise.

isOrthographic virtual bool Lens::is_orthographic(void) const; Description: Returns true if the lens represents a orthographic projection (i.e. it is a OrthographicLens), false otherwise.

isPerspective virtual bool Lens::is_perspective(void) const; Description: Returns true if the lens represents a perspective projection (i.e. it is a PerspectiveLens), false otherwise.

makeBounds virtual PointerTo< BoundingVolume > Lens::make_bounds(void) const; Description: Allocates and returns a new BoundingVolume that encloses the frustum used for this kind of lens, if possible. If a suitable bounding volume cannot be created, returns NULL.

makeCopy virtual PointerTo< Lens > Lens::make_copy(void) const = 0; Undocumented function.

makeGeometry virtual PointerTo< Geom > Lens::make_geometry(void); Description: Allocates and returns a new Geom that can be rendered to show a visible representation of the frustum used for this kind of lens, if it makes sense to do so. If a visible representation cannot be created, returns NULL.

output virtual void Lens::output(ostream &out) const; Description:

project bool Lens::project(LPoint3f const &point3d, LPoint3f &point2d) const; Description: Given a 3-d point in space, determine the 2-d point this maps to, in the range (-1,1) in both dimensions, where (0,0) is the center of the lens and (-1,-1) is the lower-left corner. Returns true if the 3-d point is in front of the lens and within the viewing frustum (in which case point2d is filled in), or false otherwise (in which case point2d will be filled in with something, which may or may not be meaningful). The z coordinate will also be set to a value in the range (-1, 1), where 1 represents a point on the near plane, and -1 represents a point on the far plane.

recomputeAll void Lens::recompute_all(void); Description: Forces all internal parameters of the Lens to be recomputed. Normally, this should never need to be called; it is provided only to assist in debugging.

setAspectRatio void Lens::set_aspect_ratio(float aspect_ratio); Description: Sets the aspect ratio of the lens. This is the ratio of the height to the width of the generated image. Setting this overrides the two-parameter fov or film size setting.

setChangeEvent void Lens::set_change_event(string const &event); Description: Sets the name of the event that will be generated whenever any properties of the Lens have changed. If this is not set for a particular lens, no event will be generated. The event is thrown with one parameter, the lens itself. This can be used to automatically track changes to camera fov, etc. in the application.

setConvergenceDistance void Lens::set_convergence_distance(float convergence_distance); Description: Sets the distance between the left and right eyes of a stereo camera. This distance is used to apply a stereo effect when the lens is rendered on a stereo display region. It only has an effect on a PerspectiveLens. Also see set_interocular_distance(), which relates.

setCoordinateSystem void Lens::set_coordinate_system(CoordinateSystem cs); Description: Specifies the coordinate system that all 3-d computations are performed within for this Lens. Normally, this is CS_default.

setFar void Lens::set_far(float far_distance); Description: Defines the position of the far plane (or cylinder, sphere, whatever). Points farther from the lens than this may not be rendered.

setFilmOffset void Lens::set_film_offset(float x, float y); Description: Sets the horizontal and vertical offset amounts of this Lens. These are both in the same units specified in set_film_size(). This can be used to establish an off-axis lens.

setFilmSize void Lens::set_film_size(float width); Description: Sets the size and shape of the "film" within the lens. This both establishes the units used by calls like set_focal_length(), and establishes the aspect ratio of the frame. In a physical camera, the field of view of a lens is determined by the lens' focal length and by the size of the film area exposed by the lens. For instance, a 35mm camera exposes a rectangle on the film about 24mm x 36mm, which means a 50mm lens gives about a 40-degree horizontal field of view. In the virtual camera, you may set the film size to any units here, and specify a focal length in the same units to simulate the same effect. Or, you may ignore this parameter, and specify the field of view and aspect ratio of the lens directly. Description: Sets the horizontal size of the film without changing its shape. The aspect ratio remains unchanged; this computes the vertical size of the film to automatically maintain the aspect ratio.

setFocalLength void Lens::set_focal_length(float focal_length); Description: Sets the focal length of the lens. This may adjust the field-of-view correspondingly, and is an alternate way to specify field of view. For certain kinds of lenses (e.g. OrthographicLens), the focal length has no meaning.

setFov void Lens::set_fov(float fov); Description: Sets the field of view of the lens in both dimensions. This establishes both the field of view and the aspect ratio of the lens. This is one way to specify the field of view of a lens; set_focal_length() is another way. For certain kinds of lenses (like OrthoLens), the field of view has no meaning. Description: Sets the horizontal field of view of the lens without changing the aspect ratio. The vertical field of view is adjusted to maintain the same aspect ratio. For certain kinds of lenses (like OrthographicLens), the field of view has no meaning.

setFrustumFromCorners void Lens::set_frustum_from_corners(LVecBase3f const &ul, LVecBase3f const &ur, LVecBase3f const &ll, LVecBase3f const &lr, int flags); Description: Sets up the lens to use the frustum defined by the four indicated points. This is most useful for a PerspectiveLens, but it may be called for other kinds of lenses as well. The frustum will be rooted at the origin (or by whatever translation might have been specified in a previous call to set_view_mat). It is legal for the four points not to be arranged in a rectangle; if this is the case, the frustum will be fitted as tightly as possible to cover all four points. The flags parameter contains the union of one or more of the following bits to control the behavior of this function: FC_roll - If this is included, the camera may be rotated so that its up vector is perpendicular to the top line. Otherwise, the standard up vector is used. FC_camera_plane - This allows the camera plane to be adjusted to be as nearly perpendicular to the center of the frustum as possible. Without this bit, the orientation camera plane is defined by position of the four points (which should all be coplanar). With this bit, the camera plane is arbitarary, and may be chosen so that the four points do not themselves lie in the camera plane (but the points will still be within the frustum). FC_off_axis - This allows the resulting frustum to be off-axis to get the tightest possible fit. Without this bit, the viewing axis will be centered within the frustum, but there may be more wasted space along the edges. FC_aspect_ratio - This allows the frustum to be scaled non-proportionately in the vertical and horizontal dimensions, if necessary, to get a tighter fit. Without this bit, the current aspect ratio will be preserved. FC_shear - This allows the frustum to be sheared, if necessary, to get the tightest possible fit. This may result in a parallelogram-based frustum, which will give a slanted appearance to the rendered image. Without this bit, the frustum will be rectangle-based. In general, if 0 is passed in as the value for flags, the generated frustum will be a loose fit but sane; if -1 is passed in, it will be a tighter fit and possibly screwy.

setInterocularDistance void Lens::set_interocular_distance(float interocular_distance); Description: Sets the distance between the left and right eyes of a stereo camera. This distance is used to apply a stereo effect when the lens is rendered on a stereo display region. It only has an effect on a PerspectiveLens. Also see set_interocular_distance(), which relates.

setKeystone void Lens::set_keystone(LVecBase2f const &keystone); Description: Indicates the ratio of keystone correction to perform on the lens, in each of three axes. This will build a special non-affine scale factor into the projection matrix that will compensate for keystoning of a projected image; this can be used to compensate for a projector that for physical reasons cannot be aimed directly at it screen. The default value is taken from the default-keystone Config variable. 0, 0 indicates no keystone correction; specify a small value (usually in the range -1 .. 1) in either the x or y position to generate a keystone correction in that axis.

setMinFov void Lens::set_min_fov(float min_fov); Description: Sets the field of view of the smallest dimension of the window. If the window is wider than it is tall, this specifies the vertical field of view; if it is taller than it is wide, this specifies the horizontal field of view. In many cases, this is preferable to setting either the horizontal or vertical field of view explicitly. Setting this parameter means that pulling the window wider will widen the field of view, which is usually what you expect to happen.

setNear void Lens::set_near(float near_distance); Description: Defines the position of the near plane (or cylinder, sphere, whatever). Points closer to the lens than this may not be rendered.

setNearFar void Lens::set_near_far(float near_distance, float far_distance); Description: Simultaneously changes the near and far planes.

setViewHpr void Lens::set_view_hpr(float h, float p, float r); Description: Sets the direction in which the lens is facing. Normally, this is down the forward axis (usually the Y axis), but it may be rotated. This is only one way of specifying the rotation; you may also specify an explicit vector in which to look, or you may give a complete transformation matrix.

setViewMat void Lens::set_view_mat(LMatrix4f const &view_mat); Description: Sets an arbitrary transformation on the lens. This replaces the individual transformation components like set_view_hpr(). Setting a transformation here will have a slightly different effect than putting one on the LensNode that contains this lens. In particular, lighting and other effects computations will still be performed on the lens in its untransformed (facing forward) position, but the actual projection matrix will be transformed by this matrix.

setViewVector void Lens::set_view_vector(float x, float y, float z, float i, float j, float k); Description: Specifies the direction in which the lens is facing by giving an axis to look along, and a perpendicular (or at least non-parallel) up axis. See also set_view_hpr().

write virtual void Lens::write(ostream &out, int indent_level = (0)) const; Description:

getClassType static TypeHandle TypedWritableReferenceCount::get_class_type(void); Undocumented function.

getClassType static TypeHandle TypedWritable::get_class_type(void); Undocumented function.

getClassType static TypeHandle TypedObject::get_class_type(void); Undocumented function.

getType virtual TypeHandle TypedObject::get_type(void) const = 0; Derived classes should override this function to return get_class_type().

getTypeIndex int TypedObject::get_type_index(void) const; Description: Returns the internal index number associated with this object's TypeHandle, a unique number for each different type. This is equivalent to get_type().get_index().

isExactType bool TypedObject::is_exact_type(TypeHandle handle) const; Description: Returns true if the current object is the indicated type exactly.

isOfType bool TypedObject::is_of_type(TypeHandle handle) const; Description: Returns true if the current object is or derives from the indicated type.

getClassType static TypeHandle ReferenceCount::get_class_type(void); Undocumented function.

getRefCount int ReferenceCount::get_ref_count(void) const; Description: Returns the current reference count.

ref void ReferenceCount::ref(void) const; Description: Explicitly increments the reference count. User code should avoid using ref() and unref() directly, which can result in missed reference counts. Instead, let a PointerTo object manage the reference counting automatically. This function is const, even though it changes the object, because generally fiddling with an object's reference count isn't considered part of fiddling with the object. An object might be const in other ways, but we still need to accurately count the number of references to it.

testRefCountIntegrity bool ReferenceCount::test_ref_count_integrity(void) const; Description: Does some easy checks to make sure that the reference count isn't completely bogus. Returns true if ok, false otherwise.

testRefCountNonzero bool ReferenceCount::test_ref_count_nonzero(void) const; Description: Does some easy checks to make sure that the reference count isn't zero, or completely bogus. Returns true if ok, false otherwise.

unref bool ReferenceCount::unref(void) const; Description: Explicitly decrements the reference count. Note that the object will not be implicitly deleted by unref() simply because the reference count drops to zero. (Having a member function delete itself is problematic; plus, we don't have a virtual destructor anyway.) However, see the helper function unref_delete(). User code should avoid using ref() and unref() directly, which can result in missed reference counts. Instead, let a PointerTo object manage the reference counting automatically. This function is const, even though it changes the object, because generally fiddling with an object's reference count isn't considered part of fiddling with the object. An object might be const in other ways, but we still need to accurately count the number of references to it. The return value is true if the new reference count is nonzero, false if it is zero.