uk.ac.starlink.ttools.plot

Class PlotVolume

java.lang.Object

uk.ac.starlink.ttools.plot.PlotVolume

Direct Known Subclasses:

BitmapSortPlotVolume, VectorSortPlotVolume, ZBufferPlotVolume

public abstract class PlotVolume
extends Object

Plots 3D points on a 2D graphics context. This is an abstract class which does much of the common work but stops short of actually drawing the points. The main problem to be solved by concrete subclasses is that of ensuring that pixels 'in front' (ones with larger Z coordinates) obscure those 'behind'.

To enable strategies which may require some kind of sorting on a full set of points prior to doing any plotting, clients of this class must first submit all the points to be plotted using the plot3D methods, and finally call flush() to ensure that the plotting has taken place.

Since:

22 Nov 2005

Author:

Mark Taylor

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	PlotVolume(Component c, Graphics g, MarkStyle[] styles, double padFactor, int[] padBorders, double fogginess) Constructor.

Method Summary

Modifier and Type	Method and Description
DataColorTweaker	createFoggingTweaker(DataColorTweaker tweaker)
abstract void	flush() Ensures that all points submitted through the plot method have been painted on the graphics context.
Fogger	getFogger() Returns the fogger used for rendering depth effects.
Graphics	getGraphics() Returns this object's graphics context.
int	getScale() Returns the scaling constant for this volume.
MarkStyle[]	getStyles() Returns the array of styles whose markers can be plotted on this volume.
static int	packRgba(float[] rgba) Utility method to convert an RGBA float[] array into an integer.
protected abstract void	plot2d(int px, int py, double z, double[] coords, int istyle, boolean showPoint, String label, int nerr, int[] xoffs, int[] yoffs, double[] zerrs) Plots an marker and optional associated error values at a given point in graphics coordinates with given additional Z coordinates.
boolean	plot3d(double[] centre, int istyle, boolean showPoint, String label, int nerr, double[] xerrs, double[] yerrs, double[] zerrs) Submits a point with associated errors for plotting.
int	projectX(double x) Determines the integer X value in graphics space from an X value in normalised 3d space.
int	projectY(double y) Determines the integer Y value in graphics space from a Y value in normalised 3d space.
static void	unpackRgba(int rgba, float[] buf) Utility method to convert an RGBA integer into a float[] array.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PlotVolume

protected PlotVolume(Component c,
                     Graphics g,
                     MarkStyle[] styles,
                     double padFactor,
                     int[] padBorders,
                     double fogginess)

Constructor.

Parameters:

c - component on which points will be plotted

g - graphics context on which points will be plotted

styles - array of marker styles which may be used to plot

padFactor - minimum amount of space outside the unit cube in both dimensions - 1 means no extra space

padBorders - space, additional to padFactor, to be left around the edges of the plot; order is (left,right,bottom,top)

fogginess - thickness of fog for depth shading

Method Detail

getStyles

public MarkStyle[] getStyles()

Returns the array of styles whose markers can be plotted on this volume.

Returns:

mark style array

getScale

public int getScale()

Returns the scaling constant for this volume. This is the value by which the normalised coordinates are multiplied to give the length on the screen in pixels of a line if it is being plotted normal to the viewer. It is approximately the linear dimension of the component in pixels.

Returns:

scale length

getFogger

public Fogger getFogger()

Returns the fogger used for rendering depth effects.

Returns:

fogger

plot3d

public boolean plot3d(double[] centre,
                      int istyle,
                      boolean showPoint,
                      String label,
                      int nerr,
                      double[] xerrs,
                      double[] yerrs,
                      double[] zerrs)

Submits a point with associated errors for plotting. The graphical effect is not guaranteed to occur until a subsequent call to flush(). The 3D point coordinates (one central point in centre and nerr additional points in xerrs, yerrs, zerrs) are in normalised coordinates, in which points inside the unit cube centred at (.5,.5,.5) are intended to be visible under normal circumstances. The ordering of the error points is that required by the ErrorRenderer class.

Note that the centre array is not guaranteed to retain its contents after this call returns; this method must make copies of the values if it needs to retain them.

The return value indicates whether the point was actually plotted; it may be false if the point was known to be off screen. This isn't guaranteed to be exact; there may be false positives or false negatives near the edge of the plotting area.

Parameters:

centre - normalised (x,y,z) coordinates of main point

istyle - index into the array of styles set up for this volume which will define how the marker is plotted

showPoint - whether the central point is to be plotted

label - label for point, or null

nerr - the number of error points, or zero for no errors

xerrs - nerr-element array of X coordinates of error points

yerrs - nerr-element array of Y coordinates of error points

zerrs - nerr-element array of Z coordinates of error points

Returns:

true iff the point was actually plotted

projectX

public int projectX(double x)

Determines the integer X value in graphics space from an X value in normalised 3d space.

Parameters:

x - normalised space X coordinate

Returns:

graphics space X coordinate

projectY

public int projectY(double y)

Determines the integer Y value in graphics space from a Y value in normalised 3d space.

Parameters:

y - normalised space Y coordinate

Returns:

graphics space Y coordinate

plot2d

protected abstract void plot2d(int px,
                               int py,
                               double z,
                               double[] coords,
                               int istyle,
                               boolean showPoint,
                               String label,
                               int nerr,
                               int[] xoffs,
                               int[] yoffs,
                               double[] zerrs)

Plots an marker and optional associated error values at a given point in graphics coordinates with given additional Z coordinates. Points with greater Z values should obscure points with lesser ones. The ordering of the error points is that required by the ErrorRenderer class.

Most implementations currently ignore the Z values associated with the error points, and put everything at the depth of the central point, because it's too hard to do otherwise. Does this produce seriously confusing visualisation?

Parameters:

px - graphics space X coordinate of the central point

py - graphics space Y coordinate of the central point

z - depth of point; a point with a greater z should obscure a point with a lesser one

coords - original coordinate array; as well as (redundant) x,y,z values it may contain auxiliary axis coordinates

istyle - index of the style used to plot the point

showPoint - whether the central point is to be plotted

label - label for point, or null

nerr - number of error points, or zero for no errors

xoffs - nerr-element array of graphics space X coordinates for error points

yoffs - nerr-element array of graphics space Y coordinates for error points

zerrs - nerr-element array of depths for error points

flush

public abstract void flush()

Ensures that all points submitted through the plot method have been painted on the graphics context.

getGraphics

public Graphics getGraphics()

Returns this object's graphics context.

Returns:

graphics context

createFoggingTweaker

public DataColorTweaker createFoggingTweaker(DataColorTweaker tweaker)

packRgba

public static int packRgba(float[] rgba)

Utility method to convert an RGBA float[] array into an integer.

Parameters:

rgba - float array

Returns:

integer

unpackRgba

public static void unpackRgba(int rgba,
                              float[] buf)

Utility method to convert an RGBA integer into a float[] array.

Parameters:

rgba - integer

buf - 4-element float array to receive result