TriD(3) User Contributed Perl Documentation TriD(3)NAMEPDL::Graphics::TriD-- PDL 3D interface
SYNOPSIS
use PDL::Graphics::TriD;
# After each graph, let the user rotate is and # wait for him to press
'q', then make new graph line3d($coords); # $coords = (3,n,...)
line3d($coords,$colors); # $colors = (3,n,...) line3d([$x,$y,$z]);
imagrgb([$r,$g,$b]); lattice3d([$x,$y,$z]); # 2-d piddles
points3d([$x,$y,$z]);
hold3d(); # the following graphs are on top of each other and the
previous line3d([$x,$y,$z]); line3d([$x,$y,$z+1]); $pic = grabpic3d();
# Returns the picture in a (3,$x,$y) float piddle (0..1).
release3d(); # the next graph will again wipe out things.
WARNING
These modules are still in a somewhat unfocused state: don't use them
yet if you don't know how to make them work if they happen to do
something strange.
DESCRIPTION
This module implements a generic 3D plotting interface for PDL.
Points, lines and surfaces (among other objects) are supported.
With OpenGL, it is easy to manipulate the resulting 3D objects with the
mouse in real time - this helps data visualization a lot.
With VRML, you can generate objects for everyone to see with e.g.
Silicon Graphics' Cosmo Player. You can find out more about VRML at
"http://vrml.sgi.com/" or "http://www.vrml.org/"
SELECTING A DEVICE
The default device for TriD is currently OpenGL. You can specify a
different device either in your program or in the environment variable
"PDL_3D_DEVICE". The one specified in the program takes priority.
The currently available devices are
GL OpenGL
GLpic OpenGL but off-line (pixmap) rendering and writing to a
graphics file.
VRML VRML objects rendering. This writes a VRML file describing the
scene. This VRML file can then be read with a browser.
ONLINE AND OFFLINE VISUALIZATION
TriD offers both on- and off-line visualization. Currently the
interface w.r.t. this division is still much in motion.
For OpenGL you can select either on- or off-line rendering. VRML is
currently always offline (this may change later, if someone bothers to
write the java(script) code to contact PDL and wait for the next
PDL image over the network.
COORDINATE SPECIFICATIONS
Specifying a set of coordinates is generally a context-dependent
operation. For a traditional 3D surface plot, you'll want two of the
coordinates to have just the xvals and yvals of the piddle,
respectively. For a line, you would generally want to have one
coordinate held at zero and the other advancing.
This module tries to make a reasonable way of specifying the context
while letting you do whatever you want by overriding the default
interpretation.
The alternative syntaxes for specifying a set of coordinates (or
colors) are
$piddle # MUST have 3 as first dim.
[$piddle]
[$piddle1,$piddle2]
[$piddle1,$piddle2,$piddle3]
[CONTEXT,$piddle]
[CONTEXT,$piddle1,$piddle2]
[CONTEXT,$piddle1,$piddle2,$piddle3]
where "CONTEXT" is a string describing in which context you wish these
piddles to be interpreted. Each routine specifies a default context
which is explained in the routines documentation. Context is usually
used only to understand what the user wants when he/she specifies less
than 3 piddles.
The following contexts are currently supported:
SURF2D A 2-D lattice. [$piddle] is interpreted as the Z coordinate
over a lattice over the first dimension. Equivalent to
[$piddle->xvals, $piddle->yvals, $piddle].
POLAR2D A 2-D polar coordinate system. [$piddle] is interpreted as the
z coordinate over theta and r (theta = the first dimension of
the piddle).
COLOR A set of colors. [$piddle] is interpreted as grayscale color
(equivalent to [$piddle,$piddle,$piddle]).
LINE A line made of 1 or 2 coordinates. [$piddle] is interpreted as
[$piddle->xvals,$piddle,0]. [$piddle1,$piddle2] is interpreted
as [$piddle1,$piddle2,$piddle1->xvals].
What makes contexts useful is that if you want to plot points instead
of the full surface you plotted with
imag3d([$zcoords]);
you don't need to start thinking about where to plot the points:
points3d([SURF2D,$zcoords]);
will do exactly the same.
SIMPLE ROUTINES
Because using the whole object-oriented interface for doing all your
work might be cumbersome, the following shortcut routines are
supported:
FUNCTIONS
line3d
3D line plot, defined by a variety of contexts.
line3d piddle(3,x), {OPTIONS}
line3d [CONTEXT], {OPTIONS}
Example:
perldl> line3d [sqrt(rvals(zeroes(50,50))/2)]
- Lines on surface
perldl> line3d [$x,$y,$z]
- Lines over X, Y, Z
perldl> line3d $coords
- Lines over the 3D coordinates in $coords.
Note: line plots differ from mesh plots in that lines only go in one
direction. If this is unclear try both!
See module documentation for more information on contexts and options
imag3d
3D rendered image plot, defined by a variety of contexts
imag3d piddle(3,x,y), {OPTIONS}
imag3d [piddle,...], {OPTIONS}
Example:
perldl> imag3d [sqrt(rvals(zeroes(50,50))/2)], {{Lines=>0};
- Rendered image of surface
See module documentation for more information on contexts and options
mesh3d
3D mesh plot, defined by a variety of contexts
mesh3d piddle(3,x,y), {OPTIONS}
mesh3d [piddle,...], {OPTIONS}
Example:
perldl> mesh3d [sqrt(rvals(zeroes(50,50))/2)]
- mesh of surface
Note: a mesh is defined by two sets of lines at right-angles (i.e. this
is how is differs from line3d).
See module documentation for more information on contexts and options
lattice3d
alias for mesh3d
points3d
3D points plot, defined by a variety of contexts
points3d piddle(3), {OPTIONS}
points3d [piddle,...], {OPTIONS}
Example:
perldl> points3d [sqrt(rvals(zeroes(50,50))/2)];
- points on surface
See module documentation for more information on contexts and options
imagrgb
2D TrueColor Image plot
imagrgb piddle(3,x,y), {OPTIONS}
imagrgb [piddle,...], {OPTIONS}
This would be used to plot an image, specifying red, green and blue
values at each point. Note: contexts are very useful here as there are
many ways one might want to do this.
e.g.
perldl> $a=sqrt(rvals(zeroes(50,50))/2)
perldl> imagrgb [0.5*sin(8*$a)+0.5,0.5*cos(8*$a)+0.5,0.5*cos(4*$a)+0.5]
imagrgb3d
2D TrueColor Image plot as an object inside a 3D space
imagrdb3d piddle(3,x,y), {OPTIONS}
imagrdb3d [piddle,...], {OPTIONS}
The piddle gives the colors. The option allowed is Points, which should
give 4 3D coordinates for the corners of the polygon, either as a
piddle or as array ref. The default is
[[0,0,0],[1,0,0],[1,1,0],[0,1,0]].
e.g.
perldl> imagrgb3d $colors, {Points => [[0,0,0],[1,0,0],[1,0,1],[0,0,1]]};
- plot on XZ plane instead of XY.
grabpic3d
Grab a 3D image from the screen.
$pic = grabpic3d();
The returned piddle has dimensions (3,$x,$y) and is of type float
(currently). XXX This should be altered later.
hold3d, release3d
Keep / don't keep the previous objects when plotting new 3D objects
hold3d();
release3d();
or
hold3d(1);
hold3d(0);
keeptwiddling3d, nokeeptwiddling3d
Wait / don't wait for 'q' after displaying a 3D image.
Usually, when showing 3D images, the user is given a chance to rotate
it and then press 'q' for the next image. However, sometimes (for e.g.
animation) this is undesirable and it is more desirable to just run one
step of the event loop at a time.
keeptwiddling3d();
nokeeptwiddling3d();
or
keeptwiddling3d(1);
keeptwiddling3d(0);
When an image is added to the screen, keep twiddling it until user
explicitly presses 'q'.
keeptwiddling3d();
imag3d(..);
nokeeptwiddling3d();
$o = imag3d($c);
while(1) {
$c .= nextfunc($c);
$o->data_changed();
twiddle3d(); # animate one step, then return.
}
twiddle3d
Wait for the user to rotate the image in 3D space.
Let the user rotate the image in 3D space, either for one step or until
(s)he presses 'q', depending on the 'keeptwiddling3d' setting. If
'keeptwiddling3d' is not set the routine returns immediately and
indicates that a 'q' event was received by returning 1. If the only
events received were mouse events, returns 0.
CONCEPTS
The key concepts (object types) of TriD are explained in the following:
Object
In this 3D abstraction, everything that you can "draw" without using
indices is an Object. That is, if you have a surface, each vertex is
not an object and neither is each segment of a long curve. The whole
curve (or a set of curves) is the lowest level Object.
Transformations and groups of Objects are also Objects.
A Window is simply an Object that has subobjects.
Twiddling
Because there is no eventloop in Perl yet and because it would be
hassleful to do otherwise, it is currently not possible to e.g. rotate
objects with your mouse when the console is expecting input or the
program is doing other things. Therefore, you need to explicitly say
"$window->twiddle()" in order to display anything.
OBJECTS
The following types of objects are currently supported. Those that do
not have a calling sequence described here should have their own manual
pages.
There are objects that are not mentioned here; they are either internal
to PDL3D or in rapidly changing states. If you use them, you do so at
your own risk.
The syntax "PDL::Graphics::TriD::Scale(x,y,z)" here means that you
create an object like
$a = new PDL::Graphics::TriD::Scale($x,$y,$z);
PDL::Graphics::TriD::LineStrip
This is just a line or a set of lines. The arguments are 3 1-or-more-D
piddles which describe the vertices of a continuous line and an
optional color piddle (which is 1-D also and simply defines the color
between red and blue. This will probably change).
PDL::Graphics::TriD::Lines
This is just a line or a set of lines. The arguments are 3 1-or-more-D
piddles where each contiguous pair of vertices describe a line segment
and an optional color piddle (which is 1-D also and simply defines the
color between red and blue. This will probably change).
PDL::Graphics::TriD::Image
This is a 2-dimensional RGB image consisting of colored rectangles.
With OpenGL, this is implemented by texturing so this should be
relatively memory and execution-time-friendly.
PDL::Graphics::TriD::Lattice
This is a 2-D set of points connected by lines in 3-space. The
constructor takes as arguments 3 2-dimensional piddles.
PDL::Graphics::TriD::Points
This is simply a set of points in 3-space. Takes as arguments the x, y
and z coordinates of the points as piddles.
PDL::Graphics::TriD::Scale(x,y,z)
Self-explanatory
PDL::Graphics::TriD::Translation(x,y,z)
Ditto
PDL::Graphics::TriD::Quaternion(c,x,y,z)
One way of representing rotations is with quaternions. See the
appropriate man page.
PDL::Graphics::TriD::ViewPort
This is a special class: in order to obtain a new viewport, you need to
have an earlier viewport on hand. The usage is:
$new_vp = $old_vp->new_viewport($x0,$y0,$x1,$y1);
where $x0 etc are the coordinates of the upper left and lower right
corners of the new viewport inside the previous (relative to the
previous viewport in the (0,1) range.
Every implementation-level window object should implement the
new_viewport method.
BUGS
Not enough is there yet.
AUTHOR
Copyright (C) 1997 Tuomas J. Lukka (lukka@husc.harvard.edu).
Documentation contributions from Karl Glazebrook
(kgb@aaoepp.aao.gov.au). All rights reserved. There is no warranty.
You are allowed to redistribute this software / documentation under
certain conditions. For details, see the file COPYING in the PDL
distribution. If this file is separated from the PDL distribution, the
copyright notice should be included in the file.
perl v5.10.0 2006-03-09 TriD(3)