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<title>Utility objects</title>
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<center>
<h2>
<u>Utility objects</u></h2></center>
There are a number of objects which were written to make it easier to use
both GEM and pd. For instance, you often pass around 3 floats at
a time in GEM, either for position or colors. To help with this,
there are a collection of vector objects. Use the list below to find
out about the objects.
<p>These objects used to be in a separate library called MarkEx, but they
have now been folded into GEM.
<p><a href="#counter">counter</a> - count the number of bangs
<br><a href="#average">average</a> - average a series of numbers together
<br><a href="#change">change</a> - only output when there is a change in
the number
<br><a href="#invert">invert</a> - invert a number
<br><a href="#randF">randomF/randF</a> - floating point random number
<br><a href="#tripleLine">tripleLine</a> - line object for 3 values
<br><a href="#tripleRand">tripleRand</a> - three random numbers
<br><a href="#vector">vector objects</a> - process a series of numbers
<br><a href="#hsv2rgb">hsv2rgb and rgb2hsv</a> - convert between RGB and
HSV color space
<p><img SRC="tribar.gif" height=13 width=561>
<h3>
<a NAME="counter"></a>counter</h3>
<center><img SRC="counter.jpg" BORDER=1 height=85 width=87></center>
<p>The inlets are:
<br>bang (increment or decrement the counter)
<br>set direction (1 = count up, 2 = count down, 3 = count up and down)
<br>set low value
<br>set hight value
<br>The outlet is the current count.
<p>So in this case, the top <i>counter</i> will count up from 1 to 10.
The bottom <i>counter</i> will count up from 2 to 5.
<p>The <i>counter</i> also accepts the messages reset and clear.
Reset immediately sets the counter to its low value and outputs the value.
The clear message means that the next bang will set the <i>counter</i>
to its low value.
<p><img SRC="tribar.gif" height=13 width=561>
<h3>
<a NAME="average"></a>average</h3>
The <i>average</i> object just averages a series of numbers as they come
in. The left inlet accepts a single float. It then outputs
the current average. The default number of floats to average together
is 10, but that can be changed by sending a new value to the right inlet.
<p>The <i>average</i> object also accepts the messages clear and reset.
Clear will immediately set all of the values that the object has been storing
for averaging to 0. With the reset message, you must pass in a number
to set all of the values.
<p><img SRC="tribar.gif" height=13 width=561>
<h3>
<a NAME="change"></a>change</h3>
<i>Change</i> only accepts a number into its left inlet. If the number
is the same as the last number sent to the <i>change</i> object, then it
does nothing. If the number is different, then the <i>change</i>
object will output the new number and store it for the next comparision.
<p>This object is very useful for the == object and others like it, since
they send a 0 or a 1 every time they do a comparision, and you usually
only care when the state actually changes.
<p><img SRC="tribar.gif" height=13 width=561>
<h3>
<a NAME="invert"></a>invert</h3>
The <i>invert</i> object is very simple. If the number sent to its
left inlet is equal to 0., then <i>invert</i> outputs a 1. If the
number is not equal to 0., the <i>invert</i> outputs a 0.
<p><img SRC="tribar.gif" height=13 width=561>
<h3>
<a NAME="randF"></a>randomF/randF</h3>
One problem with the <i>random</i> object in pd is that it only sends out
integers. This a real problem in GEM, where you often want a value
between 0 and 1. <i>randomF</i> is exactly like the <i>random</i>
object.
<p>When the left inlet gets a bang, <i>randomF</i> outputs a random number
between 0 and the given range. The range can be set with a number
to the right inlet.
<p><i>randF</i> is just an alternate name for <i>randomF</i>.
<p><img SRC="tribar.gif" height=13 width=561>
<h3>
<a NAME="tripleLine"></a>tripleLine</h3>
<center><img SRC="tripleLine.jpg" BORDER=1 height=92 width=111></center>
<p>The <i>line</i> object is really great for dealing with a single number.
To do a line with 3 values, like an RGB color value, means that you have
to unpack, do a <i>line</i>, then repack the number. Not only is
it a pain, but it expensive computationally.
<p><i>tripleLine</i> behaves just like the <i>line</i> object, only it
accepts three numbers to interpolate between. In the example, <i>tripleLine</i>
will interpolate from the current values to 1., .2, .4 over 1000 milliseconds.
The default output resolution is 50 milliseconds, which is the same default
rendering time. Going faster with GEM objects will not produce any
benefit, unless you increase the frames per second.
<p><img SRC="tribar.gif" height=13 width=561>
<h3>
<a NAME="tripleRand"></a>tripleRand</h3>
<center><img SRC="tripleRand.jpg" BORDER=1 height=89 width=149></center>
<p>Just as using <i>tripleLine</i> makes it easier to interpolate between
3 values at once, <i>tripleRand</i> makes it easy to generate three random
values. In the above example, when the bang is sent, <i>tripleRand</i>
will create three values and output them, with the first between 0 - 1,
the second between 0 - .5, and the third from 0 - .8.
<p><img SRC="tribar.gif" height=13 width=561>
<h3>
<a NAME="vector"></a>Vector objects</h3>
The vector math objects are
<br><i>vector+ </i>or<i> v+</i>
<br><i>vector- </i>or<i> v-</i>
<br><i>vector* </i>or<i> v*</i>
<br><i>vector/ </i>or<i> v/</i>
<br>All of the above objects perform math on a list of numbers. The
left inlet accepts a list of numbers of any length. The right inlet
accepts a single value, which is the operand for the computation.
In other words, they work just like the normal *, +, -, and / objects,
except they can handle more than one number in the left inlet.
<p>There are two other objects which are also useful.
<p>The first is <i>vectorabs </i>or<i> vabs</i>. It computes the absolute
value on a list of numbers.
<p>The second object is <i>vectorpack </i>or<i> vpack</i>. <i>vpack</i>
accepts a list of numbers in the left inlet and a single number into the
right inlet. The output is a single list of numbers that is the vector
with the single number appended to the end. This is very useful when
you want to change the time for a <i>tripleLine</i> without unpacking and
repacking all of the data.<i></i>
<p><img SRC="tribar.gif" height=13 width=561>
<h3>
<a NAME="hsv2rgb"></a>hsv2rgb and rgb2hsv</h3>
These two objects convert three numbers between HSV and RGB color space.
HSV stands for hue, saturation, and value. The simple way to think
of HSV space is that hue is the "color", such as red, blue, etc, the saturation
is how intense the color is, and the value is how bright the color is.
<p>You can get some really nice effects by varying the hue of a color,
because the brightness will not change while you do it.
<p><img SRC="tribar.gif" height=13 width=561>
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