# Questions tagged [mathematics]

Use of maths inside blender.

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### Source to read about the math in World Matrix and Blender's use of quaternions?

I'm going to show some slides about using Blender to illustrate three dimensional and time-evolved physics simulations by just (pasting and) running the python within the blender user interface. ...
272 views

### Does the Vector Math Normalize operation use the second input?

The Vector Math node has an operation called Normalize. I have always presumed that this is a monadic operator which ignores the second input and returns a unit vector in the direction of the input ...
220 views

### What does the “unused” output on the Vector Math node do?

The Vector Math node has two output sockets, Vector (vector type) and Value (scalar type). Most of the vector operations (Normalize, Cross Product, Average, Subtract, and Add) result in vectors, what ...
955 views

### Closing “Fibonacci's Hole”

Creating a sphere using the points defined by Spherical Fibonacci Mapping. For the most part it is easy to "skin" by using two consecutive fibonacci numbers as steps to loop on the index. And get ...
399 views

I'm working on a add-on for Blender, and part of this add-on requires me to calculate the position verts along the arc of an ellipse. At the moment, I'm using the { ...
138 views

### Normalize mix shader fac to .75 as midpoint instead of .5

(I'm not really sure of the proper way to title this question, so feel free to edit.) I am mixing 4 shaders together: 1 diffuse and 3 toon diffuse, as seen in the image. By default, I want them all ...
112 views

### Why ray_cast is behaving like this?

Why the result of ray_cast function is giving me that result? The hit point should be Vector(0.5, -1.0, 0.0), but it is returning ...
117 views

### One node group input override another

I have a procedural texture node group that is being commonly used by a lot of materials as part of a global shader setup for a project. For a few objects in the scene, I want to use a image texture ...
180 views

### How does blender work? [closed]

I am new to 3D modelling and blender, I come from a programming background, I am fascinated by the kind of things blender can do. The more I use blender the more questions I have and the more confused ...
73 views

### Multiple Random numbers per material [duplicate]

I want to randomize several procedural textures in the same material. For example, have 3 different Noise textures with a random number as their Scale. I can use the Random output of the Object Info ...
367 views

### get the rotation of a face

I'm trying to get the rotation of bmeshs face. Unfortunately following function doesn't work: ...
141 views

### Blender Math Square

I want to make a square with the scale of "8.1". The square should be hollow and inside the square are 81 other smaller squares with the scale of "0.3" Is there a way to automatically do this without ...
1k views

### How do you create a Math Formula for a Model Object?

In Carrara 4.0 Pro, I am able to create various modeling objects using math. The UI comes with 4 sliders (p1, p2, p3, p4), with values varying from -1 to +1 or -pi to +pi, and a text area for the ...
582 views

### Why does Quaternion.rotation_difference() always return 12.666471 for x-rotation?

I tried to calculate the angle between two vectors. First 3 Quaternion rotations (qx,qy,qz) are defined and multiplied to q. A vector v (1,0,0) is rotated by q. From the vectors q and qrot I want ...
210 views

### How to perform trig functions on a vector element-wise?

I'd like to get the cosine of all elements in a Vector in Blender's python. Should I just use numpy for this? Edit: I was tired when I wrote this and kind of mis-posed the question. What I actually ...
843 views

### Which of Blender's bpy.props properties can store a Matrix?

In my script I am trying to store a Matrix, for example the region_3d.view_matrix of a 3D view. This returns: ...
570 views

### Additive Emission in Cycles [duplicate]

Question is how to create additive shader. If you need particles which just "add" light to a scene. Not render a surface but create emission. If color changes from yellow to red for example, the ...
455 views

### How to project a 3D Bone POSE Matrix to 2D (XZ) Plane?

I have a Posebone Matrix which I want to project to the Front (XZ) View. Currently the bone axis can direct anywhere because they can have a custom bone roll which can direct the axis anywhere. I want ...
518 views

### How to get transform values that would be set from inserting visual key-frame for pose bones?

I have some bones with any number of constraints. I want to get the visual transform matrix of that bones that takes also into account when for example a stretch to constraint modifies that bone. So ...
117 views

### What algorithm does Blender's motion tracking use? [duplicate]

I would like to know what kind of algorithm Blender uses in motion tracking?
38 views

### Looking for a correct formula

I have set up a scene in the bge where I need to animate the mist. I have an object that loops between 0 and 4999 and I assigned its action current frame number to a property called 'axisT' Now I want ...
1k views

### BGE - Calculate Acceleration from Velocity

I need to calculate acceleration of my rigid-body object in Blender Game Engine. What I did now is: ...
2k views

### Possible to use object speed/acceleration as driver variable?

If I have an animated moving object, is it possible to get its speed and/or acceleration vector into a driver variable? Some ideas I've thought of and haven't worked out: Obviously differentiating ...
1k views

### IES-like lights in Cycles

I have been consistently trying and failing to recreate the techniques described in the links to create an IES like textured light effect with Cycles Spotlight lamps using a Color Ramp node. http://...
8k views

### What is Dot Product?

I am doing this Blenderguru tutorial on Making Fire and at some point he is adding the Vector Math node Dot Product to his material. And he says that he does not understand what he is doing but this ...
3k views

### Using Blender for plotting graphs?

While gnuplot is serviceable and matplotlib is a popular choice for Python developers, I wanted to use Python for plotting some simple graphs (matplotlib had some issues installing on my system, with ...
100 views

### How to preserve UV coordinate in python scripts when faces are transformed?

I'm writing python scripts that preserve UV coordinates when faces are translated/rotated/scaled. And I know similar feature exists in Presages Creator. https://youtu.be/QH3G9qZgjfw?t=3m32s ...
243 views

### How can I align faces that share an edge in Python? (without moving the common edge)

I need to set a face's direction from a Python script using bpy modules. I tried the below code, but it does not work correctly. ...
3k views

### How can I create 3D surface of sine waves?

I would like to make a surface that obeys the equation: z = Asin(x) + Asin(y), 0<=z<=1; 0<=x<=2npi; 0<=y<=2npi Where I would like to be able to change n to increase/decrease the ...
75 views

### Detect when object is sliding backwards

I am working on a skateboarding game and I need to detect when an object is moving backwards so the character can change stance and the controls will swap. For example after doing a 180, or when ...
2k views

### Sine wave using only Math nodes?

For the purpose of animating materials, is there a way to construct a sine wave function out of Math nodes? A while back I asked about how to do something similar with scripted driver expressions. ...
2k views

### How to find all objects in the Camera's view with Python?

I have a scene with a many objects and one camera. I would like to select the objects that the camera sees, even partially. Is there a way to do that in Python that accounts for the objects bounds? ...
8k views

### how are the math node operations in cycles calculated?

How does the math node do calculations with a specific operation: the usual operations of add,subtract, multiply and divide are quite understandable and are(empirically) very similar to some of the ...
703 views

### Can a shape key be negative?

It seems shape keys can't manually be set to a negative number or a number larger than 1. I've even tried using a driver to drive the value of the shape key beyond either of these extremes with no ...
406 views

### Why does “sin(frame)” where frame is “1” set a shape key to 0.841 and not 0.017?

I am trying to animate a shape key oscillating between -1 and 1 by driving it with the expression "sin(frame)". I would expect that to result in the shape key value being "0" at frame 0 and 180, a ...
5k views

### What is the C# Mathf.Lerp equivalent in Python?

I have a basic menu script with a slider. The idea is that the slider will control the rotation of a bone. That bone will then rotate the object. I worked out the exact euler angles to rotate it by, ...
438 views

### Why can't I type simple formulas when using transforms? [duplicate]

what its happening here? i just want to rotate R 360/5 but if do that the math function turns in to something like R [1/(360)] ...
289 views

### Create a compositing node 2D Vector from individual x & y components

A node I want to use requires it's inputs to be Vectors. However, video tracking nodes output separate x & y components, not a Vector. I can't seem to find any node that allows me to create a ...
187 views

### What happens when you plug a BSDF into a value socket?

What happens when you plug a BSDF (shader) socket into a value (float/color/vector) socket, or vice-versa? Obviously there is no way to convert a function to a value, so what does blender do? From ...
2k views

### What does the “Absolute” setting in the Math node do?

The documentation is a little unclear. "Always return non-negative value from any operation input 2 between input 1." https://...
1k views

### How to delete all faces with distance to other object

I want to delete all faces (of "Mesh") with a distance > 0.5 to the nearest point of an other object ("Sphere"). Unfortunately it deletes the whole object. Thanks for helping! ...
705 views

### How to intersect two planes?

I am trying to use the geometry.intersect_plane_plane function, but I can't use the results properly. On this tryout, we have two points (...
5k views

### What do glossy distribution models do?

In Cycles, the glossy (and anisotropic) shaders have a Distribution option. Since I don't really know the difference, I have always left it at it's default (GGX). So what is a distribution model, ...
2k views

### Build color ramp out of math nodes?

I want to use color ramps or RGB curve effects in my node groups. This runs into the problem that the only sockets these nodes have is their input image and factor. This means if I have them in a ...
591 views

### Particles and Random Numbers and Cycles Render

Goal. Have access to a random number in range [0-1] per particle per frame in a Cycles Render Node. Particle System is used. Multiple particles per frame. Question. How can Blender drivers/other ...
478 views

### How to make a F-curve with a constant and linear part?

As part of a problem I need to obtain a curve in the graph editor, that has a constant part , followed by a linear one. for instance: for the interval [0,100] the curve is y=0 for the ...
66 views

### How to display a number as output value in node-editor? [duplicate]

I would like to input a numeric value and output also a numeric value after it has gone through some nodes realizing a mathematical function. I know how to realize the mathematical function with ...
404 views

### Scripts: Converting Quaternions to Pre/Post Rotations

An issue that I've noticed while working on models for a specific game engine, is that when using exporting FBX models or BVH data comes the fact that you have two different rotations formats, with ...