class Viewport in Tinman.Terrain.Visibility

The Viewport class represents a viewport of a perspective projection used by a 3D application.

sealed class

Viewport

extends

VersionedBase

Remarks

Instances of this class are used to project terrain-space error values and bounding spheres to screen-space. This is done using an isotropic metric, which is derived from the following values:

error' = error * scale / distance
scale  = size / fov

where error is the terrain-space error value, distance is the distance from the terrain vertex to the camera position, size is the viewport size in screen pixels along the field of view, fov is the field of view angle in radians and error' is the resulting screen-space error value.

Public / Attributes

AspectRatio

The aspect ratio of the viewport.

public property	AspectRatio { get }
type	float64
value	[>0]	The new aspect ratio (i.e. width divided by height).

BaseFieldOfView

The base field of view angle.

public property	BaseFieldOfView { get set }
type	float64
value	[0..360]	The base field of view angle, in degrees. Set to 0 to disable the base field of view handling. Defaults to 0.

Remarks:

Depending on Mode, the angle is either measured along the viewports X-axis (Horizontal) or Y-axis (Vertical).

When the current field of view of the viewport is smaller than the base field of view angle given by this method, the viewport is considered to be zoomed in. In this case, terrain-space error values of vertices that lie inside the viewport (see Inside) are projected using the actual viewport field of view (i.e. the zoomed in one), whereas error values of the other vertices are projected using the base field of view:

+-----------------------------+
|                             |
|           +-----+           |
|           |ooooo|           |
|           |ooooo|           |
|           |ooooo|           |
|           +-----+           |
|                             |
+-----------------------------+

This way, additional detail due to zooming is only generated in the visible area (the 'o's in the above figure, which are inside the viewport quadrilateral). Otherwise, additional detail would be introduced into the whole mesh, which would quickly exhaust the vertex capacity.

See also:

IsZoomed
Inside

FieldOfView

The current field of view angle, in degrees.

public property	FieldOfView { get set }
type	float64
value	[0..360]	The current field of view angle, in degrees.

Remarks:

Depending on Mode, the angle is either measured along the viewports X-axis ( Horizontal) or Y-axis (Vertical).

See also:

Inside

FieldOfViewX

Returns the field-of-view along the viewport X-axis.

public property	FieldOfViewX { get }
type	float64
value	[0..360]	The horizontal field-of-view, in degrees.

FieldOfViewY

Returns the field-of-view along the viewport Y-axis.

public property	FieldOfViewY { get }
type	float64
value	[0..360]	The vertical field-of-view, in degrees.

Height

The viewport height.

public property	Height { get }
type	int32
value	[>0]	The viewport height, in pixels.

See also:

SetSize

IsZoomed

Is the viewport currently zoomed in?

public property	IsZoomed { get }
type	bool
value		true if the viewport is zoomed in, false if not.

See also:

BaseFieldOfView

Mode

The current field of view angle mode.

public property	Mode { get set }
type	FovMode
value		The field of view mode. Defaults to Vertical.

Version

Returns the current version of object.

public property	Version { get }
type	int32
value		The current version number.
inherited	VersionedBase.Version

Remarks:

For each modification, the version is incremented by at least one.

Width

The viewport width.

public property	Width { get }
type	int32
value	[>0]	The viewport width, in pixels.

See also:

SetSize

Public / Constructors

Viewport

Creates a new instance of Viewport.

public constructor	Viewport (int32 width = 1024, int32 height = 768, float64 fieldOfView = 70, FovMode mode = FovMode.Vertical)
params	width	[>0]	The viewport width, in screen pixels. Defaults to 1024.
	height	[>0]	The viewport height, in screen pixels. Defaults to 768.
	fieldOfView	[0..360]	The field of view angle, in degrees. Defaults to 70.
	mode		The field of view angle mode. Defaults to Vertical

Public / Methods

ComputeFieldOfView

Computes a field-of-view angle that avoids fish-eye distortions.

[Pure]
public static method	ComputeFieldOfView (int32 width, int32 height, float64 fov = 50.625, float64 max = 90, FovMode mode = FovMode.Vertical)
type	float64
params	width	[>0]	The viewport width.
	height	[>0]	The viewport height.
	fov	[>0]	The desired field-of-view angle (according to mode), in degrees. Defaults to 50.625.
	max	[>0]	The maximum field-of-view angle to enforce both horizontally and vertically, in degrees. Defaults to 90.
	mode		The field-of-view mode. Defaults to Vertical.
returns		[>0]	The resulting field-of-view angle, in degrees.

Inside

Checks if the given point or sphere is at least partially inside of the viewport frustum.

[Pure]
public method	Inside (float64 eyeX, float64 eyeY, float64 eyeZ, float64 radius = 0)
type	bool
params	eyeX		X-component of eye vector (point to camera), in camera space (see remarks).
	eyeY		Y-component of eye vector (point to camera), in camera space (see remarks).
	eyeZ		Z-component of eye vector (point to camera), in camera space (see remarks).
	radius		Radius of sphere or 0 for a point. Defaults to 0.
returns			true if the point or sphere is at least partially inside of the viewport frustum, false if it is outside of it.

Remarks:

The point position must be specified in camera space: The positive Z-axis is the camera direction, the positive Y-axis is the camera upwards direction and the X-axis is the camera side direction (cartesian handedness is not relevant for this method).

See also:

FieldOfViewX
FieldOfViewY

Project

Projects a given error value from terrain-space to screen-space.

[Pure]
public method	Project (float64 error, float64 distanceToCamera, bool useBaseFov = false)
type	float64
params	error		The terrain-space error value.
	distanceToCamera		Distance to camera, in terrain-space.
	useBaseFov		Use the given base field of view (see BaseFieldOfView) instead of the current field of view? Defaults to false.
returns			The screen-space error value.

ProjectSqr

Projects a given error value from terrain-space to screen-space.

[Pure]
public method	ProjectSqr (float64 errorSqr, float64 distanceToCameraSqr, bool useBaseFov = false)
type	float64
params	errorSqr		The squared terrain-space error value.
	distanceToCameraSqr		Squared distance to camera, in terrain-space.
	useBaseFov		Use the given base field of view (see BaseFieldOfView) instead of the current field of view? Defaults to false.
returns			The squared screen-space error value.

SetSize

Sets the viewport size.

public method	SetSize (int32 width, int32 height)
params	width	[>0]	The viewport width, in pixels.
	height	[>0]	The viewport height, in pixels.

See also:

Inside

Unproject

Projects a given error value from screen-space to terrain-space.

[Pure]
public method	Unproject (float64 error, float64 distanceToCamera, bool useBaseFov = false)
type	float64
params	error		The screen-space error value.
	distanceToCamera		Distance to camera, in terrain-space.
	useBaseFov		Use the given base field of view (see BaseFieldOfView) instead of the current field of view? Defaults to false.
returns			The terrain-space error value.

UnprojectSqr

Projects a given error value from screen-space to terrain-space.

[Pure]
public method	UnprojectSqr (float64 errorSqr, float64 distanceToCameraSqr, bool useBaseFov = false)
type	float64
params	errorSqr		The squared screen-space error value.
	distanceToCameraSqr		Squared distance to camera, in terrain-space.
	useBaseFov		Use the given base field of view (see BaseFieldOfView) instead of the current field of view? Defaults to false.
returns			The squared terrain-space error value.