Camera utility functions. More...

Functions
void	CalculateLookAt (const dv3 &interestPointEcef, const v3 &interestBasisFoward, float pitchRadians, float distanceCameraToInterest, dv3 &out_cameraLocation, v3 &out_cameraDirection, v3 &out_cameraUp)
	calculate a coordinate frame for positioning and orienting a camera to look towards an interest point More...

void	CalculateCameraOrientation (const v3 &viewDirection, const v3 &upAxis, m33 &out_cameraOrientation)
	create a rotation matrix suitable for orienting a camera More...

float	GetAbsoluteBearingRadians (const dv3 &pointEcef, const v3 &headingDirection)
	calculate an absolute bearing in radians from an ECEF point and heading direction More...

v3	GetScreenPositionFromLatLong (const Eegeo::Space::LatLong &latLong, const RenderCamera &renderCamera)
	project a latitude and longitude coordinate in the 3D world to a screen coordinate More...

v3	GetScreenPositionFromLatLongAlt (const Eegeo::Space::LatLongAltitude &latLongAlt, const RenderCamera &renderCamera)
	project a latitude, longitude & altitude coordinate in the 3D world to a screen coordinate More...

v3	GetScreenPositionFromEcef (const dv3 &ecefPosition, const RenderCamera &renderCamera)
	project an ECEF coordinate in the 3D world to a screen coordinate More...

void	GetScreenPickRay (const RenderCamera &renderCamera, float screenPixelX, float screenPixelY, dv3 &out_rayDirection)
	create a ray in ECEF coordinates passing through camera origin and a screen at pixel coordinates More...

bool	TryGetScreenPickIntersectionWithEarthCentredSphere (const RenderCamera &renderCamera, float screenPixelX, float screenPixelY, double sphereRadius, dv3 &out_ecefIntersectionPoint)
	Attempt to find the intersection point of a sphere centred at ECEF origin, with a ray from camera origin and passing through a point defined in screenspace. More...

void	EcefTangentBasisFromPointAndHeading (const dv3 &pointEcef, float absoluteHeadingDegrees, Space::EcefTangentBasis &out_basis)
	Create an Ecef tangent space coordinate frame from a point and a bearing angle. More...

v3	CameraRelativePoint (const dv3 &pointEcef, const dv3 &cameraOrigin)
	calculate the single-precision vector to translate from cameraOrigin to pointEcef More...

void	GetAltitudeInterpolatedNearFar (float absoluteCameraAltitude, float approxTerrainAltitude, float approxTerrainAltitudeDelta, const double scalingFunctionAltitudeThreshold, float &out_nearDistance, float &out_farDistance)
	calculate a recommended near and far clipping plane distance based on camera altitude and height of terrain to ensure everything is within the frustum More...

Geometry::Ray	ScreenPointToRay (const v2 &screenPoint, const v2 &screenDimensions, const m44 &inverseViewProjectionMatrix, const dv3 &viewOriginEcef)

dv3	ScreenPointToRayDirection (const v2 &screenPoint, const v2 &screenDimensions, const m44 &inverseViewProjectionMatrix)

v3	ClipCoordToScreenPoint (const v4 &clipCoord, const v2 &screenDimensions)

bool	TryScreenProject (const dv3 &pointEcef, const dv3 &cameraOriginEcef, const m44 &viewProjectionMatrix, const v2 &screenDimensions, v3 &out_screenPoint)

v3	ScreenProjectWithDefaultHomogeneousW (const dv3 &pointEcef, const dv3 &cameraOriginEcef, const m44 &viewProjectionMatrix, const v2 &screenDimensions, const float defaultHomogeneousW)

float	VerticalFieldOfViewFromProjection (const m44 &projectionMatrix)

float	NearClipDistanceFromProjection (const m44 &projectionMatrix)

float	FarClipDistanceFromProjection (const m44 &projectionMatrix)

CameraState	BuildCameraStateFromRenderCamera (const RenderCamera &camera, const dv3 &cameraInterestPointEcef)

Detailed Description

Camera utility functions.

Function Documentation

void Eegeo::Camera::CameraHelpers::CalculateCameraOrientation	(	const v3 &	viewDirection,
		const v3 &	upAxis,
		m33 &	out_cameraOrientation
	)

create a rotation matrix suitable for orienting a camera

Parameters

viewDirection	view direction of camera in ECEF space
upAxis	up direction of camera in ECEF space.
out_cameraOrientation	[out] resultant camera model-to-world rotation matrix

void Eegeo::Camera::CameraHelpers::CalculateLookAt	(	const dv3 &	interestPointEcef,
		const v3 &	interestBasisFoward,
		float	pitchRadians,
		float	distanceCameraToInterest,
		dv3 &	out_cameraLocation,
		v3 &	out_cameraDirection,
		v3 &	out_cameraUp
	)

calculate a coordinate frame for positioning and orienting a camera to look towards an interest point

Parameters

interestPointEcef	location of camera interest point in ECEF coordinates
interestBasisFoward	direction vector defining the azimuth orientation of the camera direction
pitchRadians	elevation angle in radians between the Earth tangent plane at interest point and the camera view direction
distanceCameraToInterest	desired distance in metres from camera origin to interest point
out_cameraLocation	[out] Camera origin in ECEF coordinates
out_cameraDirection	[out] Camera view direction in ECEF space
out_cameraUp	[out] Camera up direction in ECEF space

v3 Eegeo::Camera::CameraHelpers::CameraRelativePoint	(	const dv3 &	pointEcef,
		const dv3 &	cameraOrigin
	)

calculate the single-precision vector to translate from cameraOrigin to pointEcef

Parameters

pointEcef	point in ECEF coordinates
cameraOrigin	camera origin location in ECEF coordinates

Returns: (pointEcef - cameraOrigin) as a single-precision vector

void Eegeo::Camera::CameraHelpers::EcefTangentBasisFromPointAndHeading	(	const dv3 &	pointEcef,
		float	absoluteHeadingDegrees,
		Space::EcefTangentBasis &	out_basis
	)

Create an Ecef tangent space coordinate frame from a point and a bearing angle.

Parameters

pointEcef	point in ECEF coordinates
absoluteHeadingDegrees	bearing angle in degrees, clockwise from North
out_basis	[out] resultant EcefTangentBasis located at pointEcef, and oriented to that out_basis.GetForward() points in the direction specified by bearing angle

float Eegeo::Camera::CameraHelpers::GetAbsoluteBearingRadians	(	const dv3 &	pointEcef,
		const v3 &	headingDirection
	)

calculate an absolute bearing in radians from an ECEF point and heading direction

Parameters

pointEcef	point in ECEF coordinates
headingDirection	direction vector in ECEF space defining an orientation at pointECEF. The heading is projected onto the Earth tangent plane at pointECEF. The bearing angle is the angle between the resultant direction, and a vector on the tangent plane pointing towards the North Pole

Returns: absolute bearing angle in radians, with 0=North, and increasing positive angles rotating clockwise through compass directions (North -> East -> South -> West)

void Eegeo::Camera::CameraHelpers::GetAltitudeInterpolatedNearFar	(	float	absoluteCameraAltitude,
		float	approxTerrainAltitude,
		float	approxTerrainAltitudeDelta,
		const double	scalingFunctionAltitudeThreshold,
		float &	out_nearDistance,
		float &	out_farDistance
	)

calculate a recommended near and far clipping plane distance based on camera altitude and height of terrain to ensure everything is within the frustum

Parameters

The	altitude in meters of the camera
The	approximate altitude of the highest terrain in the scene
The	difference between the highest and lowest terrain in the scene
Altitude	at which the method for scaling the near/far bounds changes (Default 15000m)
out_nearDistance	[out] resultant recommended Near value based on the provided altitudes
out_farDistance	[out] resultant reecommended Far value based on the provided altitudes

void Eegeo::Camera::CameraHelpers::GetScreenPickRay	(	const RenderCamera &	renderCamera,
		float	screenPixelX,
		float	screenPixelY,
		dv3 &	out_rayDirection
	)

create a ray in ECEF coordinates passing through camera origin and a screen at pixel coordinates

Parameters

renderCamera	camera object defining world, view and projection camera transforms
screenPixelX	horizonal screen coordinate in pixels
screenPixelY	vertical screen coordinate in pixels
out_rayDirection	[out] resultant ray direction. The ray origin is renderCamera.GetEcefLocation()

v3 Eegeo::Camera::CameraHelpers::GetScreenPositionFromEcef	(	const dv3 &	ecefPosition,
		const RenderCamera &	renderCamera
	)

project an ECEF coordinate in the 3D world to a screen coordinate

Parameters

The	ECEF coordinate in the world to project to screen
The	RenderCamera used to display the world.

Returns: The projection of the ECEF position on the screen, where X and Y represent a viewport coordinate and Z represents the depth in the frustum.

v3 Eegeo::Camera::CameraHelpers::GetScreenPositionFromLatLong	(	const Eegeo::Space::LatLong &	latLong,
		const RenderCamera &	renderCamera
	)

project a latitude and longitude coordinate in the 3D world to a screen coordinate

Parameters

The	LatLong coordinate in the world to project to screen
The	RenderCamera used to display the world.

Returns: The projection of the LatLong on the screen, where X and Y represent a viewport coordinate and Z represents the depth in the frustum.

v3 Eegeo::Camera::CameraHelpers::GetScreenPositionFromLatLongAlt	(	const Eegeo::Space::LatLongAltitude &	latLongAlt,
		const RenderCamera &	renderCamera
	)

project a latitude, longitude & altitude coordinate in the 3D world to a screen coordinate

Parameters

The	LatLongAlt coordinate in the world to project to screen
The	RenderCamera used to display the world.

Returns: The projection of the LatLongAlt on the screen, where X and Y represent a viewport coordinate and Z represents the depth in the frustum.

bool Eegeo::Camera::CameraHelpers::TryGetScreenPickIntersectionWithEarthCentredSphere	(	const RenderCamera &	renderCamera,
		float	screenPixelX,
		float	screenPixelY,
		double	sphereRadius,
		dv3 &	out_ecefIntersectionPoint
	)

Attempt to find the intersection point of a sphere centred at ECEF origin, with a ray from camera origin and passing through a point defined in screenspace.

Parameters

renderCamera	camera object defining world, view and projection camera transforms
screenPixelX	horizonal screen coordinate in pixels
screenPixelY	vertical screen coordinate in pixels
sphereRadius	radius of sphere in metres, typically Eegeo::Space::EarthConstants::Radius for the Earth
out_ecefIntersectionPoint	[out] intersection point between ray and sphere, in ECEF space

Returns: true if ray and sphere intersect, false otherwise

Functions

Detailed Description

Function Documentation