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Help creating poltocar shader in

Dec 01 2011 | 11:35 pm

Thanks to Wesley’s advice around shaders, I’ve dived head first into Gen. I’m trying to create a poltocar shader in… but I’m not a shader geometry guru (yet ;). After unsuccessful attempts hacking examples/jitter-examples/gen/, I tried to simplify using cartopol and poltocar objects. I get displacement, but not classic cartopol or poltocar. I’d greatly appreciate any help achieving poltocar in

Work in progress copied below.


— Pasted Max Patch, click to expand. —
Dec 01 2011 | 11:59 pm

I think it’s because you’re using [norm] instead of [snorm]. norm ranges from [0, 1]. snorm ranges from [-1, 1].

-- Pasted Max Patch, click to expand. --

Dec 02 2011 | 1:49 am

Thanks for the reply, Wes! Unfortunately, while changing from [norm] to [snorm] creates a cool effect, it still looks very dissimilar to the same effects in Photoshop (which I’m assuming to be a valid benchmark). Since you added chilis.jpg to the file, I’ve attached screen grabs of chilis.jpg processed with cartopol in both Photoshop and Gen. I’ve also done the same for poltocar.

Note also that the results of the simple cartopol object alone are significantly different from those achieved with the example patch provided with Max 6. (I didn’t grab an image of that, but I can if helpful.

Thanks again!

Dec 02 2011 | 4:00 am

For this cartopol and poltocar stuff, photoshop has designed a filter with similar names that happen to use those functions and also do some shifting, scaling, and swizzling of coordinates. cartopol and poltocar are your standard polar rect functions in the gen world

-- Pasted Max Patch, click to expand. --

-- Pasted Max Patch, click to expand. --


Dec 02 2011 | 4:44 pm

Thanks, Wes! You rock! ;)

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