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2: Procedural Textures

You can get the file for the Value Graph Tool here: https://cloud.blender.org/p/procedural-shading/5f075c60f11c51bf02b95fa1

Download the resulting file here:

Blender File
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chapter_2-2.blend

Hello Simon, can i know how blender process when i divide some value by 0 ?

@Simon Thommes i see, thank you Simon

Thnaks for this tutorial :)))

@Tyler Stephens The great thing about arctan2 is that you don't only pass in the quotient of the coordinates `x/y`

but both coordinates individually. That's how you don't have to worry about the divisor being `0`

and that's also how it's possible to gain values of the full 2pi range.

How it works is basically that the function is evaluated differently depending on what quadrant the coordinates are in.

@Tighe Racicot The length of 3D coordinates is simply their distance from the origin. So on a cube that has a dimension on the z axis the z component also contributes to that distance. On a plane, where z=0 this does not matter but with the cube for example it does, as the z-component distorts the distance from the center. You can see the effect gradually have an effect when you scale the cube on the z-axis in edit mode down to a plane.

By ignoring the z-component you essentially use the distance from the z-axis, instead of the distance to the origin point. (cylindric vs spherical)

@Simon Thommes Thanks so much. I reviewed the video and it clicked.

@Ellie MacQueen I'm glad you're enjoying it! Basically the 'Map Range' node, under the hood, does the same thing as the multiply add node. It is just much more convenient due to the inputs that it takes.

In this example: Multiplying by 0.5 brings values from a range [-1 : 1] to a range [-0.5 : 0.5]. Then adding 0.5 brings it from there to [0 : 1]. So in total from [-1 : 1] to [0 : 1], which can directly specify as limits in the 'Map Range' node. The 'Map Range' node essentially just uses its inputs to find out what values it needs to multiply and add.

To be honest, if I made this video today, I wouldn't have included the 'Multiply Add' node at all here, as it just unnecessarily complicates things. But I hope this helps!

I'm not sure what you mean with 'in vector terms' here. Both nodes operate on values and a vector in Blender is just a container of 3 independent values. So to apply the same mapping to vectors you would have to either separate the components and control them individually or use vector math operations. (there is also a 'Vector Curves' node that I keep forgetting about)

***@Greg McKim*** You are right, I added the file in the description

***@Simon Thommes*** Thanks much!

So much good info here, but I'm going to need to watch it about 10 times, lol

***@Michael Schwarz*** The optput of the map range node, because clamping is activated, is strictly between its 'To' range (0 and 1). And because the RGB Curves node operates between 0 and 1 as well, the output of that node is also in that range.

The map range node is there to map the range of coordinates that the shape will be created on to the range in which the RGB Curves node operates.

***@Simon Thommes***
Thanks for the reply. It took me some time and some trying but now I'd got it.

**@Pablo Gonzalez*** There should not have been any changes regarding the absolute node. I tested it on 2.83.5 and it works fine. My guess would be that you are accidentally clamping the negative values to 0 in an operation before, but that is hard to pin down without seeing the setup. You can post a screenshot and I'll take a look.

@Simon Thommes what is the function of CLAMP? I also made the same mistake.

***@Simon Thommes*** Exactly !! It was clamped. Thank you for your fast answer

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