# DisplayRegion¶

class DisplayRegion

A rectangular subregion within a window for rendering into. Typically, there is one DisplayRegion that covers the whole window, but you may also create smaller DisplayRegions for having different regions within the window that represent different scenes. You may also stack up DisplayRegions like panes of glass, usually for layering 2-d interfaces on top of a 3-d scene.

Inheritance diagram

void clear_cull_callback(void)

Removes the callback set by an earlier call to set_cull_callback().

void clear_draw_callback(void)

Removes the callback set by an earlier call to set_draw_callback().

PN_stdfloat get_bottom(int i = 0) const

Retrieves the y coordinate of the bottom edge of the rectangle within its GraphicsOutput. This number will be in the range [0..1].

NodePath get_camera(Thread *current_thread = Thread::get_current_thread()) const

Returns the camera associated with this DisplayRegion, or an empty NodePath if no camera is associated.

static TypeHandle get_class_type(void)
CallbackObject *get_cull_callback(void) const

Returns the CallbackObject set by set_cull_callback().

CullTraverser *get_cull_traverser(void)

Returns the CullTraverser that will be used to draw the contents of this DisplayRegion.

void get_dimensions(PN_stdfloat &l, PN_stdfloat &r, PN_stdfloat &b, PN_stdfloat &t) const
void get_dimensions(int i, PN_stdfloat &l, PN_stdfloat &r, PN_stdfloat &b, PN_stdfloat &t) const
LVecBase4 get_dimensions(int i = 0) const

Retrieves the coordinates of the DisplayRegion’s rectangle within its GraphicsOutput. These numbers will be in the range [0..1].

CallbackObject *get_draw_callback(void) const

Returns the CallbackObject set by set_draw_callback().

bool get_incomplete_render(void) const

Returns the incomplete_render flag. See set_incomplete_render().

PN_stdfloat get_left(int i = 0) const

Retrieves the x coordinate of the left edge of the rectangle within its GraphicsOutput. This number will be in the range [0..1].

int get_lens_index(void) const

Returns the specific lens of the associated Camera that will be used for rendering this scene. Most Cameras hold only one lens, but for multiple lenses this method may be used to selected between them.

int get_num_regions(void) const

Returns the number of regions, see set_num_regions().

GraphicsPipe *get_pipe(void) const

Returns the GraphicsPipe that this DisplayRegion is ultimately associated with, or NULL if no pipe is associated.

int get_pixel_height(int i = 0) const

Returns the height of the DisplayRegion in pixels.

LVecBase2i get_pixel_size(int i = 0) const

Returns the size of the DisplayRegion in pixels.

int get_pixel_width(int i = 0) const

Returns the width of the DisplayRegion in pixels.

PN_stdfloat get_right(int i = 0) const

Retrieves the x coordinate of the right edge of the rectangle within its GraphicsOutput. This number will be in the range [0..1].

bool get_scissor_enabled(void) const

Returns whether or not scissor testing is enabled for this region. The default is true, except for the overlay display region.

bool get_screenshot(PNMImage &image)
PointerTo<Texture> get_screenshot(void)

Captures the most-recently rendered image from the framebuffer into the indicated PNMImage. Returns true on success, false on failure.

Captures the most-recently rendered image from the framebuffer and returns it as a Texture, or NULL on failure.

int get_sort(void) const

Returns the sort value associated with the DisplayRegion.

Lens::StereoChannel get_stereo_channel(void) const

Returns whether the DisplayRegion is specified as the left or right channel of a stereo pair, or whether it is a normal, monocular image. See set_stereo_channel().

int get_target_tex_page(void) const

Returns the target page number associated with this particular DisplayRegion, or -1 if it is not associated with a page. See set_target_tex_page().

int get_tex_view_offset(void) const

Returns the current texture view offset for this DisplayRegion. This is normally set to zero. If nonzero, it is used to select a particular view of any multiview textures that are rendered within this DisplayRegion.

For a StereoDisplayRegion, this is normally 0 for the left eye, and 1 for the right eye, to support stereo textures.

int get_texture_reload_priority(void) const

Returns the priority which is assigned to asynchronous texture reload requests. See set_texture_reload_priority().

PN_stdfloat get_top(int i = 0) const

Retrieves the y coordinate of the top edge of the rectangle within its GraphicsOutput. This number will be in the range [0..1].

GraphicsOutput *get_window(void) const

Returns the GraphicsOutput that this DisplayRegion is ultimately associated with, or NULL if no window is associated.

bool is_active(void) const

Returns the active flag associated with the DisplayRegion.

virtual bool is_stereo(void) const

Returns true if this is a StereoDisplayRegion, false otherwise.

virtual PointerTo<PandaNode> make_cull_result_graph(void)

Returns a special scene graph constructed to represent the results of the last frame’s cull operation.

This will be a hierarchy of nodes, one node for each bin, each of which will in term be a parent of a number of GeomNodes, representing the geometry drawn in each bin.

This is useful mainly for high-level debugging and abstraction tools; it should not be mistaken for the low-level cull result itself, which is constructed and maintained internally. No such scene graph is normally constructed during the rendering of a frame; this is an artificial construct created for the purpose of making it easy to analyze the results of the cull operation.

static Filename make_screenshot_filename(std::string const &prefix = "screenshot")

Synthesizes a suitable default filename for passing to save_screenshot().

The default filename is generated from the supplied prefix and from the Config variable screenshot-filename, which contains the following strings:

%~p - the supplied prefix %~f - the frame count %~e - the value of screenshot-extension All other % strings in strftime().

virtual void output(std::ostream &out) const
bool save_screenshot(Filename const &filename, std::string const &image_comment = "")

Saves a screenshot of the region to the indicated filename. Returns true on success, false on failure.

Filename save_screenshot_default(std::string const &prefix = "screenshot")

Saves a screenshot of the region to a default filename, and returns the filename, or empty string if the screenshot failed. The filename is generated by make_screenshot_filename().

virtual void set_active(bool active)

Sets the active flag associated with the DisplayRegion. If the DisplayRegion is marked inactive, nothing is rendered.

Don’t call this in a downstream thread unless you don’t mind it blowing away other changes you might have recently made in an upstream thread.

virtual void set_camera(NodePath const &camera)

Sets the camera that is associated with this DisplayRegion. There is a one-to-many association between cameras and DisplayRegions; one camera may be shared by multiple DisplayRegions.

The camera is actually set via a NodePath, which clarifies which instance of the camera (if there happen to be multiple instances) we should use.

Don’t call this in a downstream thread unless you don’t mind it blowing away other changes you might have recently made in an upstream thread.

void set_cube_map_index(int cube_map_index)

Deprecated; replaced by set_target_tex_page().

void set_cull_callback(CallbackObject *object)

Sets the CallbackObject that will be notified when the DisplayRegion is visited during the cull traversal. This callback will be made during the cull thread.

The cull traversal is responsible for determining which nodes are visible and within the view frustum, and for accumulating state and transform, and generally building up the list of CullableObjects that are to be eventually passed to the draw traversal for rendering.

At the time the cull traversal callback is made, the traversal for this DisplayRegion has not yet started.

The callback is passed an instance of a DisplayRegionCullCallbackData, which contains pointers to the current scene information, as well as the current DisplayRegion and GSG. The callback replaces the normal cull behavior, so if your callback does nothing, the scene graph will not be traversed and therefore nothing will be drawn. If you wish the normal cull traversal to be performed for this DisplayRegion, you must call cbdata->upcall() from your callback.

virtual void set_cull_traverser(CullTraverser *trav)

Specifies the CullTraverser that will be used to draw the contents of this DisplayRegion. Normally the default CullTraverser is sufficient, but this may be changed to change the default cull behavior.

void set_dimensions(PN_stdfloat l, PN_stdfloat r, PN_stdfloat b, PN_stdfloat t)
void set_dimensions(int i, PN_stdfloat l, PN_stdfloat r, PN_stdfloat b, PN_stdfloat t)
void set_dimensions(LVecBase4 const &dimensions)
virtual void set_dimensions(int i, LVecBase4 const &dimensions)

Changes the portion of the framebuffer this DisplayRegion corresponds to. The parameters range from 0 to 1, where 0,0 is the lower left corner and 1,1 is the upper right; (0, 1, 0, 1) represents the whole screen.

Changes the portion of the framebuffer this DisplayRegion corresponds to. The parameters range from 0 to 1, where 0,0 is the lower left corner and 1,1 is the upper right; (0, 1, 0, 1) represents the whole screen.

Changes the portion of the framebuffer this DisplayRegion corresponds to. The parameters range from 0 to 1, where 0,0 is the lower left corner and 1,1 is the upper right; (0, 1, 0, 1) represents the whole screen.

Changes the portion of the framebuffer this DisplayRegion corresponds to. The parameters range from 0 to 1, where 0,0 is the lower left corner and 1,1 is the upper right; (0, 1, 0, 1) represents the whole screen.

Don’t call this in a downstream thread unless you don’t mind it blowing away other changes you might have recently made in an upstream thread.

void set_draw_callback(CallbackObject *object)

Sets the CallbackObject that will be notified when the contents of DisplayRegion is drawn during the draw traversal. This callback will be made during the draw thread.

The draw traversal is responsible for actually issuing the commands to the graphics engine to draw primitives. Its job is to walk through the list of CullableObjects build up by the cull traversal, as quickly as possible, issuing the appropriate commands to draw each one.

At the time the draw traversal callback is made, the graphics state is in the initial state, and no projection matrix or modelview matrix is in effect. begin_scene() has not yet been called, and no objects have yet been drawn. However, the viewport has already been set to the appropriate part of the window, and the clear commands for this DisplayRegion (if any) have been issued.

The callback is passed an instance of a DisplayRegionDrawCallbackData, which contains pointers to the current scene information, as well as the current DisplayRegion and GSG. The callback replaces the normal draw behavior, so if your callback does nothing, nothing in the DisplayRegion will be drawn. If you wish the draw traversal to continue to draw the contents of this DisplayRegion, you must call cbdata->upcall() from your callback.

virtual void set_incomplete_render(bool incomplete_render)

Sets the incomplete_render flag. When this is true, the frame will be rendered even if some of the geometry or textures in the scene are not available (e.g. they have been temporarily paged out). When this is false, the frame will be held up while this data is reloaded.

This flag may also be set on the GraphicsStateGuardian. It will be considered true for a given DisplayRegion only if it is true on both the GSG and on the DisplayRegion.

See GraphicsStateGuardian::set_incomplete_render() for more detail.

void set_lens_index(int index)

Sets the lens index, allows for multiple lenses to be attached to a camera. This is useful for a variety of setups, such as fish eye rendering. The default is 0.

Don’t call this in a downstream thread unless you don’t mind it blowing away other changes you might have recently made in an upstream thread.

void set_num_regions(int i)

Sets the number of regions that this DisplayRegion indicates. Usually, this number is 1 (and it is always at least 1), and only the first is used for rendering. However, if more than one is provided, you may select which one to render into using a geometry shader (gl_ViewportIndex in GLSL).

void set_scissor_enabled(bool scissor_enabled)

Sets whether or not scissor testing is enabled for this region. The default is true, except for the overlay display region.

virtual void set_sort(int sort)

Sets the sort value associated with the DisplayRegion. Within a window, DisplayRegions will be rendered in order from the lowest sort value to the highest.

Don’t call this in a downstream thread unless you don’t mind it blowing away other changes you might have recently made in an upstream thread.

virtual void set_stereo_channel(Lens::StereoChannel stereo_channel)

Specifies whether the DisplayRegion represents the left or right channel of a stereo pair, or whether it is a normal, monocular image. This automatically adjusts the lens that is used to render to this DisplayRegion to its left or right eye, according to the lens’s stereo properties.

When the DisplayRegion is attached to a stereo window (one for which is_stereo() returns true), this also specifies which physical channel the DisplayRegion renders to.

Normally you would create at least two DisplayRegions for a stereo window, one for each of the left and right channels. The two DisplayRegions may share the same camera (and thus the same lens); this parameter is used to control the exact properties of the lens when it is used to render into this DisplayRegion.

Also see the StereoDisplayRegion, which automates managing a pair of left/right DisplayRegions.

An ordinary DisplayRegion may be set to SC_mono, SC_left, or SC_right. You may set SC_stereo only on a StereoDisplayRegion.

This call also resets tex_view_offset to its default value, which is 0 for the left eye or 1 for the right eye of a stereo display region, or 0 for a mono display region.

virtual void set_target_tex_page(int page)

This is a special parameter that is only used when rendering the faces of a cube map or multipage and/or multiview texture.

This sets up the DisplayRegion to render to the ith page and jth view of its associated texture(s); the value must be consistent with the range of values availble to the texture. A normal DisplayRegion that is not associated with any particular page should be set to page -1 and view 0.

This is particularly useful when rendering cube maps and/or stereo textures.

Don’t call this in a downstream thread unless you don’t mind it blowing away other changes you might have recently made in an upstream thread.

virtual void set_tex_view_offset(int tex_view_offset)

Sets the current texture view offset for this DisplayRegion. This is normally set to zero. If nonzero, it is used to select a particular view of any multiview textures that are rendered within this DisplayRegion.

For a StereoDisplayRegion, this is normally 0 for the left eye, and 1 for the right eye, to support stereo textures. This is set automatically when you call set_stereo_channel().

virtual void set_texture_reload_priority(int texture_reload_priority)

Specifies an integer priority which is assigned to any asynchronous texture reload requests spawned while processing this DisplayRegion. This controls which textures are loaded first when multiple textures need to be reloaded at once; it also controls the relative priority between asynchronous texture loads and asynchronous model or animation loads.

Specifying a larger number here makes the textures rendered by this DisplayRegion load up first. This may be particularly useful to do, for instance, for the DisplayRegion that renders the gui.