Tag Archives: interpolate

Nov 12 2014

Cross CHOP tutorial.

The Cross CHOP. TouchDesigner 088. 2014.
The Cross CHOP is a multi-input Channel Operator that allows you to interpolate between input values.

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Let’s examine the cross CHOP.

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The cross CHOP allows you to
switch between multiple inputs,
but interpolate between the
incoming values.

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You can use integers as cross
values to simply switch between
inputs.

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I’ve created a box SOP with its
“sizex” parameter referencing
the cross CHOP channel named
“chan1”.

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This will help you visualize the
cross CHOPs’ effect.

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The interpolation is straight,
or linear, so a cross value of
.5 will blend the first 2 inputs
at 50% each.

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The cross CHOP is a commonly
used operator that can
compliment or replace standard
switching.

Nov 12 2014

Join CHOP tutorial.

The Join CHOP. TouchDesigner 088. 2014.
The Join CHOP can append multiple types of incoming channel datatypes. This allows you to sculpt or craft specialty waveforms.

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Let’s examine the join CHOP.

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I’ve set up 3 example networks
here, each network illustrates
different approaches to using
the join CHOP.

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In this network we will append 3
CHOPs together.

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We start with the ramp from 0 to
1, and end with a ramp from 1 to
0.

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In the middle we have a noise
CHOP.

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As you can see, the join CHOP
will stack one CHOP after the
next.

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Using the “Preserve Length”
method, with no blending or
overlap interpolation, the CHOPs
are simply appended together.

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We can better visualize the join
by changing the seed parameter
of the noise CHOP.

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By maintaining an overlap region
of 0, any overlap shape
parameter I choose has no
effect.

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In the second example network,
we’ll look at the “Insert Blend
Region” option of the method
parameter.

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We join 3 chops with single
sample values of 0, 1, and .5.

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We can see that the join CHOP
has interpolated a simple ramp
between the incoming values.

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By using the “Insert Blend
Region” method, we can define an
overlap region between each
incoming value.

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We can also control the shape of
the overlap blend.

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As I increase the overlap
region, you’ll see that the join
CHOP creates a smoother and
smoother interpolation between
the incoming values.

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It does this by creating more
samples than the total of the
original inputs.

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It uses the extra samples to
create more fine tuned steps
between the original inputs.

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In this example we’ll use the
“Overlap Sequences” method to
join the to incoming waveforms.

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We’ll join a triangle and a sine
wave, and you’ll notice that
there is a disparity in the end
value of input 1, and the start
value of input 2.

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We want to interpolate between
these 2 values, to create a
smooth join.

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This is similar to adjusting
Bezier handles on keyframes, or
points on a spline.

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As I increase the overlap
region, you’ll see the join
become smoother and smoother.

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If I use the “Cubic”
interpolation method, I can
shift the bias.

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This will determine the
influence that either the first
or second input will have on the
overlap.

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The join CHOP parameters are
very powerful, and will allow
you to fine tune your blends to
an exact specification.

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Nov 12 2014

Blend CHOP tutorial.

The Blend CHOP. TouchDesigner 088. 2014.
The Blend CHOP is a special multi-input CHOP. It can combine CHOP Channel values using different weighting calculations.

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Let’s examine the blend CHOP.

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The blend CHOP is very powerful,
but its usage can be difficult
to understand.

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Unlike other CHOPs that combine
multiple inputs, the blend CHOP
uses its first input as a
controller.

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The reason for this architecture
is that the blend CHOP can
control an arbitrary amount of
inputs.

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The second input is a base
value.

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These are the values that all
other inputs will be compared
to.

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This network uses 3 states, plus
a base state.

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We will use the “Difference”
method for blending the incoming
channels.

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The states of “rx”, “ry”, and
“rz” represent rotations, and
they are applied to a geometry
component by using Python
expressions.

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The base state is 0 rotation.

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Adjusting its amount with the
controller has no effect.

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This is because we are using the
“Difference” method.

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Try using the “Proportional”
method to blend in the base
state.

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Now I increase the amount of
influence of state 1.

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Again, notice that the base
state is only calculated as a
comparative starting point.

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I’ll increase the influence of
state 1 to its maximum value.

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No other states are influencing
the blend.

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In this way the blend CHOP can
be used as a simple switch.

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Now I’ll begin combining states.

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The blend CHOP calculates state
influences in real time.

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It can be used as a way to morph
any type of value or state in
Touch Designer.