It depends if you're on Mac, Windows or Linux.
I'm on MacOS and I use Gem without Pd-extended. I just have to use Pd-Vanilla 32 bits (Pd-0.49-0-i386) and I've downloaded Gem via Help -> Find Externals -> Gem (in the research) and you choose the version from Deken Gem 0.93.3. Install it. Close Pure Data.
To load Gem when you're starting PureData : Open Pure data and go to Pd -> Preferences -> StartUp . In the StartUp Flags you tape Gem, 'Enter' and you juste have to close Pd and re-open and you can use Gem.
With cmd+B, you open the Help Browser and you have a Gem section with all the help you'll need to understand Gem (I've started two months ago).
Have Fun !

I'll try to find something in the toolkit, maybe I'll find the solution to do that.
Thx !

@whale-av said:

https://forum.pdpatchrepo.info/topic/3835/blur-gemframebuffer

Yes I'm working with [glsl_vertex], [glsl_fragment] and [glsl_program].
In Gem exemples like "simple_texture.pd", they use [pix_image] in the pd patch (in the gemhead chaine, after [glsl_program]) to load a image.jpg.
They create a "uniform sampler2D MyTex;" in the .frag.
I don't understand the link between MyTex and [pix_image].

I'm trying to do the same in the shader (from shadertoy in my first post) by replacing "float noise( in vec2 x ){return texture(iChannel0, x*.01).x;}" by
"float noise( in vec2 x ){return texture2D(MyTex, x*.01).x;}",
after I had create my uniform sampler2D MyTex; of course.
I'm loading the same texture it's use in shadertoy but It does nothing.
There is not so many tutorial about glsl in Pure Data...

Hey there
I'm trying to import a shader from ShaderToy in Pure data and I don't know what to do about "iChannel0". What can I do in my shader.frag ?
The use of "iChannel" (0, 1 and more) in ShaderToy is clear but I don't know how transform it for Pure Data. It appear everytime a shader use a noise animation and it's happend often.
An example of a shader with this function line 19 https://www.shadertoy.com/view/lslXRS

Any advice is appreciated. Thank you.

Thx LiamG and LarsXI.
It's working great, just notice that it need to write [pack symbol $0] and [read -resize $1 $2-audio( .
In the same time, I found a great tutoriel for this kind of issue on reddit , it's perfect to really understand how to use abstractions and $0. https://www.reddit.com/r/puredata/comments/7w3yc4/advice_in_building_a_patch_with_different_sampler/

Hi there !
I'm using the message [read resize $1 Audio] just after an Openpanel object to read a sound in an array named Audio with the object tabread4~ Audio.
It's working great and I want to use my patch as an abstraction but I've issue with the use of $0.
I 've named my array $0-Audio, I've writen tabread4~ $0-Audio and [read -resize $1 $0-Audio]. Pd send me "0-Audio : no such table".
I don't understand what I have to write in the message [read -resize] to solve the problem.
If someone could help me for this, it will be nice.

I'm new here, I've created a account just to ask this because I've not found a real response about this in particular.