vkf_view – vkframes

Camera views: where the camera looks from, as OpenFrames' View.

A view follows a frame: the camera's trackball (eye, center, up, which the mouse moves) is kept in the view frame's coordinates, so the camera moves with the frame. The view frame is * RELATIVE_FRAME (the default): the viewed frame itself (a body-fixed view); * ABSOLUTE_FRAME: the root frame's axes, at the viewed frame's origin (an inertial view that follows the frame as it moves). A view between frames (set_view_between_frames) looks from one frame at another: the view frame is turned so that its +y axis (the trackball's initial viewing direction) points at the second frame, in one direct rotation (VIEW_DIRECT) or first in azimuth, then elevation (VIEW_AZEL, the default, which keeps z up).

The default camera (reset_view) looks along +y at the frame's bound from the distance at which it fills the field of view (or from default_view_distance, or from set_default_view_parameters). Views are not owned by windows: a view, and the frames it refers to, must stay alive while used.

The camera (OpenFrames' trackball get/setTransformation): a window's get_camera / set_camera for the view it shows (and smooth transitions, see vkf_window), or set_camera for a view's camera when it is next shown. camera_between interpolates between two cameras (each eye, center, up): the center along a straight line, the distance geometrically, the orientation by the shortest rotation.

Uses

- vkf_math
- vkf_frames
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Used by

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Solid arrows point from a submodule to the (sub)module which it is descended from. Dashed arrows point from a module or program unit to modules which it uses.

Variables

Type	Visibility	Attributes		Name		Initial
integer,	public,	parameter	::	ABSOLUTE_FRAME	=	0	the base frame of the trackball (OpenFrames' ViewFrameType) the root frame's axes, at the viewed frame's origin
integer,	public,	parameter	::	ORTHOGRAPHIC	=	0	projections (OpenFrames' ProjectionType) orthographic projection
integer,	public,	parameter	::	PERSPECTIVE	=	1	perspective projection
integer,	public,	parameter	::	RELATIVE_FRAME	=	1	the viewed frame itself
integer,	public,	parameter	::	VIEW_AZEL	=	1	azimuth, then elevation (keeps z up)
integer,	public,	parameter	::	VIEW_DIRECT	=	0	how a view between frames turns toward the look-at frame (OpenFrames' ViewRotationType) one direct rotation

Interfaces

public interface View

The View constructor: View(...) makes one (see new_view for its arguments).

private function new_view(root, frame, lookat, frame_type, rotation_type) result(v)

A view of frame (in the tree of root), with base frame_type (default RELATIVE_FRAME); with lookat, a view from frame at lookat, turned by rotation_type (default VIEW_AZEL). Without frames, the view looks at the root frame's origin. The frames must stay alive while the view is used.

Arguments

Type	Intent	Optional	Attributes		Name
class(ReferenceFrame),	intent(in),	optional,	target	::	root	the tree's root, viewed and looked-at frames
class(ReferenceFrame),	intent(in),	optional,	target	::	frame	the tree's root, viewed and looked-at frames
class(ReferenceFrame),	intent(in),	optional,	target	::	lookat	the tree's root, viewed and looked-at frames
integer,	intent(in),	optional		::	frame_type	ABSOLUTE_FRAME or RELATIVE_FRAME
integer,	intent(in),	optional		::	rotation_type	VIEW_DIRECT or VIEW_AZEL

Return Value type(View)

Derived Types

type, public :: View

A view (see the module documentation).

Components

Type	Visibility	Attributes		Name		Initial
logical,	private		::	camera_pending	=	.false.	true if `pending` is to be applied when shown
real(kind=wp),	private		::	center(3)	=	0.0_wp	kept center
real(kind=wp),	private		::	default_center(3)	=	0.0_wp	camera center after a reset (view-frame coordinates)
real(kind=wp),	private		::	default_distance	=	0.0_wp	radius framed on reset (<= 0: the frame's bound)
real(kind=wp),	private		::	default_eye(3)	=	0.0_wp	camera eye after a reset (view-frame coordinates)
real(kind=wp),	private		::	default_up(3)	=	0.0_wp	camera up after a reset (zero: no default camera)
real(kind=wp),	private		::	eye(3)	=	0.0_wp	kept eye
real(kind=wp),	private		::	fovy	=	45.0_wp	vertical field of view (degrees)
class(ReferenceFrame),	private,	pointer	::	frame	=>	null()	the viewed frame (not owned)
integer,	private		::	frame_type	=	RELATIVE_FRAME	ABSOLUTE_FRAME or RELATIVE_FRAME
logical,	private		::	has_state	=	.false.	true if eye, center, up are kept
class(ReferenceFrame),	private,	pointer	::	lookat	=>	null()	the frame looked at (view between frames; not owned)
real(kind=wp),	private		::	ortho(4)	=	[-1.0_wp, 1.0_wp, -1.0_wp, 1.0_wp]	left, right, bottom, top
real(kind=wp),	private		::	pending(3,3)	=	0.0_wp	a camera set (eye, center, up), for when it is shown
integer,	private		::	projection	=	PERSPECTIVE	ORTHOGRAPHIC or PERSPECTIVE
logical,	private		::	reset_pending	=	.true.	true if the camera is to be reset when shown
class(ReferenceFrame),	private,	pointer	::	root	=>	null()	the root of the frames' tree (not owned)
integer,	private		::	rotation_type	=	VIEW_AZEL	VIEW_DIRECT or VIEW_AZEL
real(kind=wp),	private		::	up(3)	=	0.0_wp	kept up direction

Constructor

The View constructor: View(...) makes one (see new_view for its arguments).

private function new_view (root, frame, lookat, frame_type, rotation_type)	A view of `frame` (in the tree of `root`), with base `frame_type` (default RELATIVE_FRAME); with `lookat`, a view from `frame` at `lookat`, turned by `rotation_type` (default VIEW_AZEL). Without frames, the view looks at the root frame's origin. The frames must stay alive while the view is used.

Type-Bound Procedures

procedure, public :: clear_default_view_parameters
procedure, public :: default_view_distance
procedure, public :: default_view_parameters
procedure, public :: field_of_view
procedure, public :: home
procedure, public :: is_valid
procedure, public :: lookat_frame
procedure, public :: orthographic_bounds
procedure, public :: projection_type
procedure, public :: reset_view
procedure, public :: save_state
procedure, public :: saved_state
procedure, public :: set_camera => view_set_camera
procedure, public :: set_default_view_distance
procedure, public :: set_default_view_parameters
procedure, public :: set_orthographic
procedure, public :: set_perspective
procedure, public :: set_view_between_frames
procedure, public :: set_view_frame
procedure, public :: take_camera
procedure, public :: take_reset
procedure, public :: view_frame
procedure, public :: view_frame_type
procedure, public :: view_root
procedure, public :: view_rotation_type
procedure, public :: world_to_view

Functions

public pure function camera_between(s, from, to) result(cam)

The camera a fraction s (0 to 1) of the way from camera from to camera to (columns: eye, center, up; in one frame's coordinates): the center moved along a straight line, the distance to it changed by the same factor at each step (so far-to-near flights don't rush the near part), and the orientation turned by the shortest rotation.

Arguments

Type	Intent		Name
real(kind=wp),	intent(in)	::	s	fraction of the way (0: `from`, 1: `to`)
real(kind=wp),	intent(in)	::	from(3,3)	(columns: eye, center, up)
real(kind=wp),	intent(in)	::	to(3,3)	(columns: eye, center, up)

Return Value real(kind=wp), (3,3)

private pure function default_view_distance(self)

The radius framed when the view is reset (<= 0: the viewed frame's bound).

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value real(kind=wp)

private pure function field_of_view(self) result(fovy)

The vertical field of view (degrees) of the perspective projection.

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value real(kind=wp)

private function frame_to_root(self, f) result(m)

The transform from f to the view's root frame (the tree root if none).

Arguments

Type	Intent	Optional	Attributes		Name
type(View),	intent(in)			::	self
class(ReferenceFrame),	intent(in)			::	f	a frame of the view's tree

Return Value real(kind=wp), (4,4)

private function is_valid(self)

True if the view has a frame to view.

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value logical

private function lookat_frame(self) result(f)

The frame looked at, for a view between frames (null if none).

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value class(ReferenceFrame), pointer

private function new_view(root, frame, lookat, frame_type, rotation_type) result(v)

Arguments

Type	Intent	Optional	Attributes		Name
class(ReferenceFrame),	intent(in),	optional,	target	::	root	the tree's root, viewed and looked-at frames
class(ReferenceFrame),	intent(in),	optional,	target	::	frame	the tree's root, viewed and looked-at frames
class(ReferenceFrame),	intent(in),	optional,	target	::	lookat	the tree's root, viewed and looked-at frames
integer,	intent(in),	optional		::	frame_type	ABSOLUTE_FRAME or RELATIVE_FRAME
integer,	intent(in),	optional		::	rotation_type	VIEW_DIRECT or VIEW_AZEL

Return Value type(View)

private pure function orthographic_bounds(self) result(bounds)

The bounds [left, right, bottom, top] of the orthographic projection.

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value real(kind=wp), (4)

private pure function projection_type(self)

The projection: ORTHOGRAPHIC or PERSPECTIVE.

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value integer

private pure function rotated(r, m) result(rm)

rotate(r) * m, for a rotation r (3x3).

Arguments

Type	Intent	Optional	Attributes		Name
real(kind=wp),	intent(in)			::	r(3,3)	rotation (3x3); transform (4x4)
real(kind=wp),	intent(in)			::	m(4,4)	rotation (3x3); transform (4x4)

Return Value real(kind=wp), (4,4)

private function saved_state(self, eye, center, up)

The kept trackball state; false if there is none.

Arguments

Type	Intent		Name
class(View),	intent(in)	::	self
real(kind=wp),	intent(out)	::	eye(3)	the kept trackball state (view-frame coordinates)
real(kind=wp),	intent(out)	::	center(3)	the kept trackball state (view-frame coordinates)
real(kind=wp),	intent(out)	::	up(3)	the kept trackball state (view-frame coordinates)

Return Value logical

private function take_camera(self, cam)

True (once) if a camera was set (set_camera), and that camera.

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(inout)			::	self
real(kind=wp),	intent(out)			::	cam(3,3)	(columns: eye, center, up (view-frame coordinates))

Return Value logical

private function take_reset(self)

True (once) if a reset is pending.

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(inout)			::	self

Return Value logical

public pure function transform_camera(m, cam) result(out)

A camera (columns: eye, center, up) in the coordinates a rigid transform m (4x4) takes it to: the points moved, the up direction turned.

Arguments

Type	Intent	Optional	Attributes		Name
real(kind=wp),	intent(in)			::	m(4,4)	rigid transform
real(kind=wp),	intent(in)			::	cam(3,3)	(columns: eye, center, up)

Return Value real(kind=wp), (3,3)

private function view_frame(self) result(f)

The viewed frame (null if none).

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value class(ReferenceFrame), pointer

private pure function view_frame_type(self)

The base of the trackball: ABSOLUTE_FRAME or RELATIVE_FRAME.

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value integer

private function view_root(self) result(f)

The root of the viewed frames' tree (null if none).

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value class(ReferenceFrame), pointer

private pure function view_rotation_type(self)

How a view between frames turns: VIEW_DIRECT or VIEW_AZEL.

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value integer

private function world_to_view(self) result(m)

The transform from the root frame to the view frame (4x4), from the frames' current positions and attitudes.

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(in)			::	self

Return Value real(kind=wp), (4,4)

Subroutines

private pure subroutine camera_orientation(cam, q, d)

A camera's orientation (columns: right, up, back, as a quaternion) and its distance from eye to center (at least a tiny one).

Arguments

Type	Intent		Name
real(kind=wp),	intent(in)	::	cam(3,3)	(columns: eye, center, up)
real(kind=wp),	intent(out)	::	q(4)	orientation quaternion [x, y, z, w]
real(kind=wp),	intent(out)	::	d	distance from eye to center

private subroutine clear_default_view_parameters(self)

Forget the camera set by set_default_view_parameters (back to the default view distance).

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(inout)			::	self

private pure subroutine default_view_parameters(self, eye, center, up)

The camera after a reset (view-frame coordinates; all zero if none is set).

Arguments

Type	Intent		Name
class(View),	intent(in)	::	self
real(kind=wp),	intent(out)	::	eye(3)	the camera (view-frame coordinates; zero if not set)
real(kind=wp),	intent(out)	::	center(3)	the camera (view-frame coordinates; zero if not set)
real(kind=wp),	intent(out)	::	up(3)	the camera (view-frame coordinates; zero if not set)

private subroutine home(self, aspect, eye, center, up)

The default camera (eye, center, up in view-frame coordinates) for a viewport of aspect ratio aspect (width / height): OpenFrames' resetView.

Arguments

Type	Intent		Name
class(View),	intent(in)	::	self
real(kind=wp),	intent(in)	::	aspect	viewport width / height
real(kind=wp),	intent(out)	::	eye(3)	the default camera (view-frame coordinates)
real(kind=wp),	intent(out)	::	center(3)	the default camera (view-frame coordinates)
real(kind=wp),	intent(out)	::	up(3)	the default camera (view-frame coordinates)

private subroutine reset_view(self)

Put the camera back at the default position (applied at the next frame in which the view is shown).

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(inout)			::	self

private subroutine save_state(self, eye, center, up)

Keep the trackball state while another view is shown.

Arguments

Type	Intent		Name
class(View),	intent(inout)	::	self
real(kind=wp),	intent(in)	::	eye(3)	the trackball state (view-frame coordinates)
real(kind=wp),	intent(in)	::	center(3)	the trackball state (view-frame coordinates)
real(kind=wp),	intent(in)	::	up(3)	the trackball state (view-frame coordinates)

private subroutine set_default_view_distance(self, distance)

The radius to frame when the view is reset (<= 0: the viewed frame's bound, the default), as OpenFrames' default view distance.

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(inout)			::	self
real(kind=wp),	intent(in)			::	distance	radius (<= 0: the frame's bound)

private subroutine set_default_view_parameters(self, eye, center, up)

The camera after a reset, in view-frame coordinates (overrides the default view distance).

Arguments

Type	Intent		Name
class(View),	intent(inout)	::	self
real(kind=wp),	intent(in)	::	eye(3)	the camera (view-frame coordinates)
real(kind=wp),	intent(in)	::	center(3)	the camera (view-frame coordinates)
real(kind=wp),	intent(in)	::	up(3)	the camera (view-frame coordinates)

private subroutine set_orthographic(self, left, right, bottom, top)

An orthographic projection with the given bounds (in view units).

Arguments

Type	Intent		Name
class(View),	intent(inout)	::	self
real(kind=wp),	intent(in)	::	left	bounds (view units)
real(kind=wp),	intent(in)	::	right	bounds (view units)
real(kind=wp),	intent(in)	::	bottom	bounds (view units)
real(kind=wp),	intent(in)	::	top	bounds (view units)

private subroutine set_perspective(self, fovy)

A perspective projection with vertical field of view fovy (degrees; default 45).

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(inout)			::	self
real(kind=wp),	intent(in)			::	fovy	vertical field of view (degrees)

private subroutine set_view_between_frames(self, root, frame, lookat, frame_type, rotation_type)

Look from frame at lookat (both in the tree of root).

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(inout)			::	self
class(ReferenceFrame),	intent(in),		target	::	root	the tree's root, viewed and looked-at frames
class(ReferenceFrame),	intent(in),		target	::	frame	the tree's root, viewed and looked-at frames
class(ReferenceFrame),	intent(in),		target	::	lookat	the tree's root, viewed and looked-at frames
integer,	intent(in),	optional		::	frame_type	ABSOLUTE_FRAME or RELATIVE_FRAME (default)
integer,	intent(in),	optional		::	rotation_type	VIEW_DIRECT or VIEW_AZEL (default)

private subroutine set_view_frame(self, root, frame, frame_type)

View frame (in the tree of root) with base frame_type (default RELATIVE_FRAME).

Arguments

Type	Intent	Optional	Attributes		Name
class(View),	intent(inout)			::	self
class(ReferenceFrame),	intent(in),		target	::	root	the tree's root; the viewed frame (not owned)
class(ReferenceFrame),	intent(in),		target	::	frame	the tree's root; the viewed frame (not owned)
integer,	intent(in),	optional		::	frame_type	ABSOLUTE_FRAME or RELATIVE_FRAME

private subroutine view_set_camera(self, eye, center, up)

The camera (view-frame coordinates) to show the next time the view is drawn (at once if it is shown: the window's set_camera can also fly there). It replaces a pending reset.

Arguments

Type	Intent		Name
class(View),	intent(inout)	::	self
real(kind=wp),	intent(in)	::	eye(3)	the camera (view-frame coordinates)
real(kind=wp),	intent(in)	::	center(3)	the camera (view-frame coordinates)
real(kind=wp),	intent(in)	::	up(3)	the camera (view-frame coordinates)

vkf_view Module

Contents

Variables

Interfaces

Derived Types

Functions

Subroutines

Uses

Used by

Variables

Interfaces

public interface View

private function new_view(root, frame, lookat, frame_type, rotation_type) result(v)

Arguments

Return Value type(View)

Derived Types

type, public :: View

Components

Constructor

Type-Bound Procedures

Functions

public pure function camera_between(s, from, to) result(cam)

Arguments

Return Value real(kind=wp), (3,3)

private pure function default_view_distance(self)

Arguments

Return Value real(kind=wp)

private pure function field_of_view(self) result(fovy)

Arguments

Return Value real(kind=wp)

private function frame_to_root(self, f) result(m)

Arguments

Return Value real(kind=wp), (4,4)

private function is_valid(self)

Arguments

Return Value logical

private function lookat_frame(self) result(f)

Arguments

Return Value class(ReferenceFrame), pointer

private function new_view(root, frame, lookat, frame_type, rotation_type) result(v)

Arguments

Return Value type(View)

private pure function orthographic_bounds(self) result(bounds)

Arguments

Return Value real(kind=wp), (4)

private pure function projection_type(self)

Arguments

Return Value integer

private pure function rotated(r, m) result(rm)

Arguments

Return Value real(kind=wp), (4,4)

private function saved_state(self, eye, center, up)

Arguments

Return Value logical

private function take_camera(self, cam)

Arguments

Return Value logical

private function take_reset(self)

Arguments

Return Value logical

public pure function transform_camera(m, cam) result(out)

Arguments

Return Value real(kind=wp), (3,3)

private function view_frame(self) result(f)

Arguments

Return Value class(ReferenceFrame), pointer

private pure function view_frame_type(self)

Arguments

Return Value integer

private function view_root(self) result(f)

Arguments

Return Value class(ReferenceFrame), pointer

private pure function view_rotation_type(self)

Arguments

Return Value integer

private function world_to_view(self) result(m)

Arguments

Return Value real(kind=wp), (4,4)

Subroutines

private pure subroutine camera_orientation(cam, q, d)