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Introduction |
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All of the IFW2 Texture shaders share the same noise generation system. This allows any texture to be stirred up
and disturbed. The frequency of the noise can be controlled (Scale) along with the size of the noise
displacement (Magnitude) and the number of noise iterations (Octaves). There is also the ability to
adapt the noise generator with its own magnitude (Noise). Finally, the noise can be modified
over time to create a either cyclic or flowing noise animation. NOTE To be accurate noise is simply a single slice of a
noise volume. These values can be used repeatedly to generate turbulence. This means that turbulence
is a number of summed noises when the number of "summings" is usually termed octaves.
IFW2 Textures contains two separate noise generation systems: Standard Noise and Flow Noise. Both add turbulence to the currently selected texture. The standard noise generator uses a standard turbulence algorithm that is implemented to give a cyclic noise function over time. The second is a flow noise algorithm which is a more sophisticated system that models the flow of gases and liquids. When the Use Flow check box is checked then the flow noise algorithm is used otherwise the standard noise algorithm is used. They both share similar controls but the control is subtly different. To see how standard noise is controlled  .
To see how the flow noise is controlled .
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| The Noise Scale Parameter | ||||||||||
The Noise Scale parameter controls the frequency of the turbulence, that is the periodic frequency.
When the scale is at a low value the turbulence will be tight and crinkled and will become increasingly
smoother as the parameter is increased. Unlike the octaves parameter the scale parameter simply changes
the turbulence's fundamental frequency (or overall size).
The figures below show the effect of increasing the Scale value of the diagonal line texture.
As you can see the period of the turbulence increases with the scale value. The allows
larger more sweeping turbulence to be generated. For these samples the octaves parameter
was set to 6, the magnitude parameter was set to 0.2 and the noise parameter 0.0.
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| The Noise Magnitude Parameter | ||||||||||
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The Noise Magnitude controls the size of the Turbulence that is used to "stir" up the texture.
As the Magnitude value is increased the amount by which the pattern is disturbed is increased.
The figures below show the effect of increasing the magnitude value of the diagonal line texture.
Notice, that the pattern becomes more noisy as the magnitude is increased. For these samples
the octaves parameter was set to 6, the scale parameter was set to 2.0 and the noise parameter 0.0. NOTE The turbulence function is only called when the Magnitude parameter is a non-zero value. As the turbulence function takes time to execute the rendering will be slower when it is switched on.
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| The Noise Octaves Parameter | ||||||||||
The Noise Octaves parameter controls the number of times noise is summed in order to generate the turbulence.
Turbulence is generated by summing noise with each summed noise being half the magnitude of the previously summed
noise. The number of times the noise is summed is determined by octaves. So, at low values the turbulence will
be smoother and will increase in detail (due to the fact that the summed noise is getting smaller) as the
number of octaves is increased. All this basically means is that the turbulence becomes more "crinkled"
as the number of octaves is increased.
The figures below show the effect of increasing the Octaves value of the diagonal line texture.
Notice, that the pattern becomes more crinkled as the number of octaves is increased. For
these samples the scale parameter was set to 0.5, the magnitude parameter was set to 0.2 and the noise parameter 0.0.
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| The Noise Noise Parameter | ||||||||||
The Noise Noise parameter controls the granularity of the turbulence. The Noise parameter is only used
when it is non-zero. As was detailed in the octaves section the turbulence is generated by summing successive
scales of noise with each scale being half the magnitude of the previous one. The noise parameter actually controls
the scaling of successive noise scales. This effectively means that the turbulence will have a finer grain with
higher values of noise.
The figures below show the effect of increasing the Noise value of the diagonal texture.
Notice, that the pattern becomes finer as the Noise parameter is increased. For these
samples the octaves parameter was set to 6, the magnitude parameter was set to 0.7 and the scale parameter 3.0.
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Animating Noise The Noise Velocity and Time Parameters | ||||||
The noise or turbulence can be animated on a cyclic basis, This means that after on complete
animation cyclic the texture will return to its ordinal position. One animation cycle is
for Time to go from 0% to 100%. The first thing is to enable the time algorithm for the
noise. This is done by checking the box next to the Noise Time parameter. The time can then
be changed using an envelope to animated over a series of frames. Remember, if the noise
goes from 0% to 100% in a number of frames it can be repeated seamlessly.
The other parameter associated with animated noise is the Velocity. As the name suggests this
controls the speed of the noise over the whole animation cycle. Basically, the higher this
value the more active the noise is.
The figures below show the effect of increasing the Velocity value of the diagonal line texture.
Notice, that the noise goes undulates more quickly as the Velocity is increased. For these
samples the octaves parameter was set to 6, the magnitude parameter was set to 0.2 and the
scale parameter 1.0. For the animation an envelope was created for time that went from 0%
to 100% is a straight line over 8 frames.
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| 3D Noise Parameter |
| This option forces the noise to be 3D. This means that the noise is generated three times and applied independently to each axis. The texture is more uniformly distorted and gives a much better result. However, with this option enabled it is three time slower. |
| The Flow Noise Scale Parameter | ||||||||||
The Noise Scale parameter controls the frequency of the turbulence, that is the periodic frequency.
When the scale is at a high value the turbulence will be tight and crinkled and will become increasingly
smoother as the parameter is decreased.
The figures below show the effect of increasing the Scale value of the diagonal line texture.
As you can see the period of the turbulence increases with the scale value. The allows
larger more sweeping turbulence to be generated. For these samples the octaves parameter
was set to 4 and the magnitude parameter was set to 0.4.
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| The Flow Noise Magnitude Parameter | ||||||||||
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The Noise Magnitude controls the size of the Turbulence that is used to "stir" up the texture.
As the Magnitude value is increased the amount by which the pattern is disturbed is increased.
The figures below show the effect of increasing the magnitude value of the diagonal line texture.
Notice, that the pattern becomes more noisy as the magnitude is increased. For these samples
the octaves parameter was set to 4 and the scale parameter was set to 1.0. NOTE The turbulence function is only called when the Magnitude parameter is a non-zero value. As the turbulence function takes time to execute the rendering will be slower when it is switched on.
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| The Flow Noise Octaves Parameter | ||||||||||
The Noise Octaves parameter controls the number of times noise is summed in order to generate the turbulence.
Turbulence is generated by summing noise with each summed noise being half the magnitude of the previously summed
noise. The number of times the noise is summed is determined by octaves. So, at low values the turbulence will
be smoother and will increase in detail (due to the fact that the summed noise is getting smaller) as the
number of octaves is increased. All this basically means is that the turbulence becomes more "crinkled"
as the number of octaves is increased.
The figures below show the effect of increasing the Octaves value of the diagonal line texture.
Notice, that the pattern becomes more crinkled as the number of octaves is increased. For
these samples the scale parameter was set to 1.0 and the magnitude parameter was set to 1.0.
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| The Flow Noise Velocity Parameter | ||||||||||
The Noise Velocity parameter controls the advection of the animated noise. That is, the amount
by which smaller noise detail is affected by the larger noise detail. Basically, in the same way as
eddies are created in larger river flows. So to put it more simply at low values the effect
is more billowing like gases or clouds and as this value increases the noise becomes more
like liquid flows.
The figures below show the effect of increasing the Velocity value of the diagonal texture.
Notice, that the pattern becomes finer as the Noise parameter is increased. For these
samples the octaves parameter was set to 4, the magnitude parameter was set to 0.3 and
the scale parameter 2.0.
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Animating Noise The Flow Noise Velocity and Time Parameters | ||||||
The flow noise can be animated by morphing the time parameter. Unlike the standard noise
algorithm the flow noise is not cyclic so time does not have a upper limit.
The figures below show the effect of increasing the Velocity value of the diagonal line texture.
Notice, that the noise goes undulates more quickly as the Velocity is increased. For these
samples the octaves parameter was set to 4, the magnitude parameter was set to 0.5 and the
scale parameter 2.0. For the animation an envelope was created for time that went from 0%
to 30% is a straight line over 16 frames.
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Fast Bump |
| This parameter controls whether the texture returns a gradient when it is being used in for bump mapping or as a displacement. When checked the texture will return a gradient which is a faster and more acturate method for bumps and displacements. |
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3D Noise |
| When the texture is using normal noise to distort the pattern this is normally a single turbulence value added to each axis. However, with this option enabled three turbulence values distort each axis independently making a much better job of the distortion. This method is better but three time slower. |
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