Package uk.ac.starlink.ttools.plot2.geom
Class SinProjection
java.lang.Object
uk.ac.starlink.ttools.plot2.geom.SkyviewProjection
uk.ac.starlink.ttools.plot2.geom.SinProjection
- All Implemented Interfaces:
Projection
Sine (orthographic) projection.
This is the one that gives you a rotatable sphere.
North always faces directly up (is aligned along the screen Y direction).
This is a singleton class, see
INSTANCE
.- Since:
- 21 Feb 2013
- Author:
- Mark Taylor
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Field Summary
Fields -
Method Summary
Modifier and TypeMethodDescriptioncreateAspect
(boolean reflect, double[] r3, double radiusRad, Range[] vxyzRanges) Creates a SkyAspect from configuration information.double[]
cursorRotate
(double[] rot0, Point2D.Double pos0, Point2D.Double pos1) Attempts to return a rotation matrix corresponding to moving the cursor between two plane positions.getFov
(SkySurface surf) Returns the field of view represented by this aspect.boolean
Indicates whether this projection is known to be continous over its whole range.boolean
isContinuousLine
(double[] r3a, double[] r3b) Indicates whether a line between the two given sky positions is (believed to be) continuous.boolean
project
(double rx, double ry, double rz, Point2D.Double pos) Overridden for slight efficiency gain.double[]
projRotate
(double[] rot0, Point2D.Double pos0, Point2D.Double pos1) Attempts to return a rotation matrix that will transform a sky position from one plane position to another.boolean
useRanges
(boolean reflect, double[] r3, double radiusRad) Indicates whether ranges should be provided to generate a SkyAspect.static double[]
verticalRotate
(double delta, double alpha, boolean reflect) Rotation matrix which results in an orientation with the viewing plane X coordinate of the north pole equal to zero.Methods inherited from class uk.ac.starlink.ttools.plot2.geom.SkyviewProjection
getProjectionDescription, getProjectionName, getProjectionShape, getSkyviewProjecter, unproject
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Field Details
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INSTANCE
Singleton instance.
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Method Details
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project
Overridden for slight efficiency gain.- Specified by:
project
in interfaceProjection
- Overrides:
project
in classSkyviewProjection
- Parameters:
rx
- normalised 3D X coordinatery
- normalised 3D Y coordinaterz
- normalised 3D Z coordinatepos
- point object into which projected dimensionless X,Y coordinates will be written on success- Returns:
- true if transformation succeeded
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isContinuous
public boolean isContinuous()Description copied from interface:Projection
Indicates whether this projection is known to be continous over its whole range. Returns false if there may be any cases for whichisContinuousLine
returns false.- Returns:
- true iff this projection is known to be continuous
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isContinuousLine
public boolean isContinuousLine(double[] r3a, double[] r3b) Description copied from interface:Projection
Indicates whether a line between the two given sky positions is (believed to be) continuous. "Line" in this context should ideally be interpreted as the shorter arc on a great circle. A line crossing lon=180 for instance would be discontinuous in an Aitoff projection, but not in a Sin projection.- Parameters:
r3a
- 3-element array giving normalised X,Y,Z coordinates of line startr3b
- 3-element array giving normalised X,Y,Z coordinates of line end- Returns:
- true if line is believed to be continuous; if in doubt, probably better to return true
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cursorRotate
Description copied from interface:Projection
Attempts to return a rotation matrix corresponding to moving the cursor between two plane positions. Ideally this should do the same thing asprojRotate
, for both positions on the sky, and provide some other intuitive behaviour if one or both is out of the projection range.Null may be returned if this projection does not support rotation.
- Parameters:
rot0
- initial rotation matrixpos0
- initial cursor positionpos1
- destination cursor position- Returns:
- destination rotation matrix, or null
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projRotate
Description copied from interface:Projection
Attempts to return a rotation matrix that will transform a sky position from one plane position to another.Consider a sky point S, rotated by an initial rotation matrix
rotmat
to S', which when projected by this projection lands on the plane atpos0
. This method attempts to determine a rotation matrix which when used instead ofrotmat
would end up with the rotated and projected point atpos1
.Null may be returned if this projection does not support projection.
- Parameters:
rot0
- initial rotation matrixpos0
- initial projected positionpos1
- destination projected position- Returns:
- destination rotation matrix, or null
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useRanges
public boolean useRanges(boolean reflect, double[] r3, double radiusRad) Description copied from interface:Projection
Indicates whether ranges should be provided to generate a SkyAspect. If supplied field of view arguments are sufficient, or if a default aspect is always produced, return false.- Parameters:
reflect
- whether requested aspect will be reflectedr3
- central position of field of view (may be null)radiusRad
- radius of field of view (may be NaN)- Returns:
- true if ranges would be useful given the other arguments
- See Also:
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createAspect
Description copied from interface:Projection
Creates a SkyAspect from configuration information. Either the supplied field of view or data ranges may be used, or neither.- Parameters:
reflect
- whether requested aspect will be reflectedr3
- central position of field of view (may be null)radiusRad
- radius of field of view (may be NaN)vxyzRanges
- definite ranges for normalised X,Y,Z coordinates acquired from data- Returns:
- new sky aspect
- See Also:
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getFov
Description copied from interface:Projection
Returns the field of view represented by this aspect. This is a best estimate, it may be approximate depending on the projection geometry. If the field of view is the default for this projection, then null should be returned. Null may also be returned if for some reason no field of view can be determined.- Parameters:
surf
- sky surface, which must be set up using this projection- Returns:
- field of view, or null
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verticalRotate
public static double[] verticalRotate(double delta, double alpha, boolean reflect) Rotation matrix which results in an orientation with the viewing plane X coordinate of the north pole equal to zero. This is a rotation invariant we wish to preserve.- Parameters:
delta
- rotation of pole from vertical (0..pi)alpha
- rotation around pole (0..2pi)reflect
- if true, alpha increases right to left- Returns:
- rotation matrix
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