This class object combines the rendered output of a 3-d from one or more linear (e.g. perspective) cameras, as seen through a single, possibly nonlinear camera.
This can be used to generate real-time imagery of a 3-d scene using a nonlinear camera, for instance a fisheye camera, even though the underlying graphics engine may only support linear cameras. It can also pre-distort imagery to compensate for off-axis projectors, and/or curved screens of any complexity.
A NonlinearImager may be visualized as a dark room into which a number of projection screens have been placed, of arbitrary size and shape and at any arbitrary position and orientation to each other. Onto each of these screens is projected the view as seen by a normal perspective camera that exists in the world (that is, under render).
There also exist in the room one or more (possibly nonlinear) cameras, called viewers, that observe these screens. The image of the projection screens seen by each viewer is finally displayed on the viewer’s associated
DisplayRegion. By placing the viewer(s) appropriately relative to the screens, and by choosing suitable lens properties for the viewer(s), you can achieve a wide variety of distortion effects.
There are several different
LensNode(Camera) objects involved at each stage in the process. To help keep them all straight, different words are used to refer to each different kind of Camera used within this object. The camera(s) under render, that capture the original view of the world to be projected onto the screens, are called source cameras, and are set per screen via
LensNodethat is associated with each screen to project the image as seen from the screen’s source camera is called a projector; these are set via the
ProjectionScreen::set_projector()interface. Finally, the cameras that view the whole configuration of screens are called viewers; each of these is associated with a
DisplayRegion, and they are set via
Of all these lenses, only the source cameras must use linear (that is, perspective or orthographic) lenses. The projectors and viewers may be any arbitrary lens, linear or otherwise.
int add_screen(NodePath const &screen, std::string const &name)
This version of this method is deprecated and will soon be removed. Use the version that takes two parameters instead.
Deprecated: Use the version that takes two parameters instead.
Adds a new
ProjectionScreento the list of screens that will be processed by the
ProjectionScreenrepresents a view into the world. It must be based on a linear camera (or whatever kind of camera is respected by the graphics engine).
ProjectionScreenobject should already have some screen geometry created.
As each frame is rendered, an offscreen image will be rendered from the source camera associated with each
ProjectionScreen, and the resulting image will be applied to the screen geometry.
The return value is the index number of the new screen.
int add_viewer(DisplayRegion *dr)
Adds the indicated
DisplayRegionas a viewer into the
NonlinearImagerroom. The camera associated with the
DisplayRegionat the time add_viewer() is called is used as the initial viewer camera; it may have a nonlinear lens, like a fisheye or cylindrical lens.
This sets up a special scene graph for this
DisplayRegionalone and sets up the
DisplayRegionwith a specialty camera. If future changes to the camera are desired, you should use the
All viewers must share the same
The return value is the index of the new viewer.
int find_screen(NodePath const &screen) const
Returns the index number of the first appearance of the indicated screen within the imager’s list, or -1 if it does not appear.
int find_viewer(DisplayRegion *dr) const
Returns the index number of the indicated
DisplayRegionwithin the list of viewers, or -1 if it is not found.
GraphicsOutput *get_buffer(int index) const
Returns the offscreen buffer that is automatically created for the nth projection screen. This may return NULL if the screen is inactive or if it has not been rendered yet.
NodePath get_dark_room(void) const
NodePathto the root of the dark room scene. This is the scene in which all of the
ProjectionScreensand the viewer cameras reside. It’s a standalone scene with a few projection screens arranged artfully around one or more viewers; it’s so named because it’s a little virtual theater.
Normally this scene is not rendered directly; it only exists as an abstract concept, and to define the relation between the
ProjectionScreensand the viewers. But it may be rendered to help visualize the NonlinearImager’s behavior.
GraphicsEngine *get_graphics_engine(void) const
int get_num_screens(void) const
Returns the number of screens that have been added to the imager.
int get_num_viewers(void) const
Returns the number of viewers that have been added to the imager.
bool get_screen_active(int index) const
Returns the active flag on the indicated screen.
DisplayRegion *get_viewer(int index) const
Returns the nth viewer’s
DisplayRegionthat has been added to the imager.
NodePath get_viewer_camera(int index) const
NodePath get_viewer_scene(int index) const
Returns a pointer to the root node of the internal scene graph for the nth viewer, which is used to render all of the screen meshes for this viewer.
This is the scene graph in which the screen meshes within the dark room have been flattened into the appropriate transformation according to the viewer’s lens properties (and position relative to the screens). It is this scene graph that is finally rendered to the window.
Forces a regeneration of all the mesh objects, etc.
Removes all screens from the imager.
Removes all viewers from the imager.
void remove_screen(int index)
Removes the screen with the indicated index number from the imager.
void remove_viewer(int index)
Removes the viewer with the indicated index number from the imager.
void set_screen_active(int index, bool active)
Sets the active flag on the indicated screen. If the active flag is true, the screen will be used; otherwise, it will not appear.
void set_source_camera(int index, NodePath const &source_camera)
Specifies the camera that will be used to render the image for this particular screen.
The parameter must be a
NodePathwhose node is a Camera. The camera itself indicates the scene that is to be rendered.
void set_texture_size(int index, int width, int height)
Sets the width and height of the texture used to render the scene for the indicated screen. This must be less than or equal to the window size, and it should be a power of two.
In general, the larger the texture, the greater the detail of the rendered scene.
void set_viewer_camera(int index, NodePath const &viewer_camera)
LensNodethat is to serve as the viewer for this screen. The relative position of the
NonlinearImager, as well as the properties of the lens associated with the
LensNode, determines the UV’s that will be assigned to the geometry within the
It is not necessary to call this except to change the camera after a viewer has been added, since the default is to use whatever camera is associated with the
DisplayRegionat the time the viewer is added.