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by ghostfish 4992 days ago
But you missed the most important part of that quote. >"(in Ready, Stephan's software at the sourceforge link above runs much faster)" So using Ready it took a long time, but the actual code is much faster. I'd imagine you could write something in CUDA that would run this (and only this, not something generalized like Ready) plenty fast to do real time rendering on a new system, especially considering a GTX 680 has almost 5x the horsepower of a GTX 460.

Admittedly not in a web browser though.
2 comments
maffydub 4992 days ago
"Admittedly not in a web browser though."

HTML5 gives you WebGL support, which allows you to compile and run GLSL shaders from JavaScript. For something that is heavily shader-oriented like this, it might be possible in the browser.

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tim_hutton 4992 days ago
Ready is using OpenCL. But Stephan is using FFT for the convolution with a disk filter, which is a big win for large radii.
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ghostfish 4992 days ago
As far as I'm aware OpenCL performance, while portable, is still somewhat inferior to that of straight CUDA on NVIDIA GPUs, hence my CUDA suggestion. I didn't actually look at the algorithms used in either so I can't comment, perhaps I'll do that tomorrow. What do you mean by using an FFT "for" a convolution? The algorithm is convolving the (presumably 2D) FFT of the game board with a disk filter?
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tim_hutton 4992 days ago
SmoothLife uses two disks around each point to determine the instantaneous rate of change. Inside each disk the values are summed. This is a convolution with a disk filter.

http://en.wikipedia.org/wiki/Convolution

As it says on that page, FFT is often used for convolution because it is fast: after applying a discrete Fourier transform to the kernel and the image, the resulting images must only be multiplied together before applying an inverse FFT.

http://en.wikipedia.org/wiki/Discrete_Fourier_transform

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ghostfish 4991 days ago
Ah, thanks for the information. I'm familiar with signal processing, so the only way I'm used to seeing convolutions is through the multiplication of FFTs. I wasn't even considering the "regular" way.
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tomrod 4991 days ago
That's so cool. I love to see real world applications of convolutions.

I wonder if there is an application of Gershgorin's Disc theorem here?

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tim_hutton 4991 days ago
I see something about a circle that contains the eigenvectors of a matrix. How does that apply here?
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