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20160912.html
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<h1>20160912 - The Great MacOS 9</h1>
<br>
This "<a href="http://arstechnica.com/apple/2016/09/an-os-9-odyssey-why-do-some-mac-users-still-rely-on-16-year-old-software/">An OS 9 odyssey: Why these Mac users won’t abandon 16-year-old software.</a>" is an awesome article. OS 9 was the peak of Apple operating systems. Low latency, instant response. If only the industry didn't fabricate internet "standards" complexity at a rate which is impossible to dream of supporting on the older machines.
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20160921.html
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<h1>20160921 - Parallel Noise Generation</h1>
<br>
Re a related <a href="https://twitter.com/pixelmager/status/778573539939127297">Twitter Post</a> ...
<br>
<br>
Concerning making tile-able textures for grain or noise, and getting various desired properties.
My preference is towards algorithms which parallelize trivially.
The <a href="https://www.shadertoy.com/view/4sBSDW">shadertoy referenced in the tweet</a>
generates a noise pattern,
by starting out with some poor non-random noise,
then applying filters (ending with a high-pass) to transform it into something which is pleasing to the eye.
I'd advise always using the technique I outlined in this <a href="http://gpuopen.com/vdr-follow-up-fine-art-of-film-grain/">GPUOpen Post</a>
which remaps the texture to a perfect distribution of values (see the <a href="http://gpuopen.com/vdr-follow-up-grain-and-fine-details/">follow up post as well</a>)
while maintaining it's original form (this applies to both techniques in this post).
<br>
<br>
A second technique I've leveraged in the past
is to work with one {x,y} coordinate for a grain position
distributed in a regular grid array of grains.
Starting with the perfect honeycomb distribution
(start from a regular grid position, where every other row is shifted to the left or right, and make the grid have proper aspect ratio for honeycomb),
<br>
<br><tt>
_x_x_x_x_x_x_x_x<br>
x_x_x_x_x_x_x_x_<br>
_x_x_x_x_x_x_x_x<br>
x_x_x_x_x_x_x_x_<br>
_x_x_x_x_x_x_x_x<br>
x_x_x_x_x_x_x_x_<br>
_x_x_x_x_x_x_x_x<br>
x_x_x_x_x_x_x_x_
</tt><br>
<br>
Then permuting grain position by some function (which could be a noise function with various distributions based on frequency,
or perhaps do some kind of clustered rotation of points by nearest cluster, etc).
This process typically results in undesired look.
Then applying various passes on the array where the position of each grain is filtered against the positions of the pre-filtered neighbors (only dependent on prior pass).
The point being to re-shape the array into something which has a more visually pleasing feel.
The filter can work with a hex neighborhood (neighbors depend on if the pixel is on a even or odd row),
<br>
<br><tt>
_x_x_ ... ab_ ... _ab<br>
x_x_x ... cde ... cde<br>
_x_x_ ... ef_ ... _ef
</tt><br>
<br>
Could be something as easy as relaxing the position of the point
(push the point in the direction towards being equal distance from neighbors, but not so much that one resets to a honeycomb).
After getting grains distributed as desired, can use for {x,y} coordinates, or transform back into an image of grain (which could be a different resolution image).
<br>
<br>
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index.html
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<a href="20161004.html">20161004 - T4K Try 3</a><br>
<a href="20161003.html">20161003 - T4K Try 2</a><br>
<a href="20161001.html">20161001 - T4K Try 1</a><br>
<a href="20160921.html">20160921 - Parallel Noise Generation</a><br>
<a href="20160912.html">20160912 - The Great MacOS 9</a><br>
<a href="20160715.html">20160715 - LED Displays</a><br>
<a href="20160127.html">20160127 - Temporal AA Neighborhood Clamp</a><br>
<br>