[Blender x Python] Let's master random !!

This time, I will introduce a mechanism to arrange a large number of objects at random.

table of contents

0. How to get a random number
1. Make a cube appear at a random position
2. Create a function to organize the process
3. Sample code
4. English words Reference material

0. How to get a random number

This time, we will use the rand () function in a library called ** numpy ** (a collection of useful code).

The rand () function returns a random value ** from ** 0 to 1. The argument (parameter) specifies how many random numbers to return. If it is rand (3), it returns 3 random numbers.

import numpy as np

#np.You can think of random as a right-pointing arrow and ignore it.
np.random.rand(3)

Point:import numpy as np The library called numpy is abbreviated as np in the code.

array([0.90681482, 0.04813658, 0.47969033])

↑ Three random values in the range 0 to 1 are output.

• Array means an array, but this time you don't have to worry about it. It's like a container with numbers in order.

1. Make a cube appear at a random position

1-0. Let's make the cube appear in random positions !!

Use the library numpy for numerical calculation

import bpy
import numpy as np

bpy.ops.mesh.primitive_cube_add(location = np.random.rand(3))

Point:rand( ) Generate a random value from 0 to 1. The argument determines how many values to return. rand (3) returns 3 random values.

• In the photo, three random values → (0.0291909, 0.379929, 0.395483) were assigned to the variable location.

1-1. Let's be able to specify the range where the cube appears

○ Gets a random number in the range of -10 or more and less than 10. The code has the following structure.

Data (information) is assigned to the variable □, and processing is executed using that data. And you can think of the dots as right-pointing arrows (almost negligible).

□ ← Random numerical data
===>function( □ )

import bpy
import numpy as np

#Variable random_Create a location and assign a random value
random_location = (10 - (-10)) * np.random.rand(3) + (-10)
bpy.ops.mesh.primitive_cube_add(location = random_location)

Point: ** Numerical value within a certain range ** An expression that gets a random value in the range min or greater and less than max (max-min) * np.random.rand() + min is.

In other words ** Range where numbers fluctuate * Random value from 0 to 1 + Start of range ** about it.

In this example, we get (random) numbers in the range +20 from -10. Range → (-10, ..-9, ..0, ..9, ..10)

2. Create a function to organize the process

2-0. Create a function that returns a random number and a function that uses it to make a cube appear.

import bpy
import numpy as np

#Definition of a function to generate three random values
def get_random_location(min,max):
    return (max - min) * np.random.rand(3) + min

#get_random_location()Definition of a function that makes a cube appear using the value generated by the function
def generate_random_cube(min,max):
    random_location = get_random_location(min,max)
    bpy.ops.mesh.primitive_cube_add(location = random_location)

generate_random_cube(-10,10)

Point:Return It is used in the form of `` return information'' when the function outputs some information.

2-1. Create a function that makes multiple cubes appear at random positions

import bpy
import numpy as np

#Definition of a function to generate three random values
def get_random_location(min,max):
    return (max - min) * np.random.rand(3) + min

#get_random_location()Definition of a function that makes a cube appear using the value generated by the function
def generate_random_cube(min,max):
    random_location = get_random_location(min,max)
    bpy.ops.mesh.primitive_cube_add(location = random_location)

#Definition of a function that causes multiple cubes to appear at random positions
def generate_random_cubes(min,max,num):
    for i in range(0,num):
        generate_random_cube(min,max)

generate_random_cubes(-10,10,200)

2-2. Make multiple cubes with random angles appear at random positions

import bpy
import math
import numpy as np

#Definition of a function to generate three random values
def get_random_location(min,max):
    return (max - min) * np.random.rand(3) + min

#random_number()Definition of a function that rotates and makes a cube appear using the value generated by the function
def generate_random_rotate_cube(min,max):
    random_location = get_random_location(min,max)
    bpy.ops.mesh.primitive_cube_add(location = random_location,rotation = math.pi * np.random.rand(3))

#Definition of a function that rotates and makes multiple cubes appear at random positions
def generate_random_rotate_cubes(min,max,num):
    for i in range(0,num):
        generate_random_rotate_cube(min,max)

generate_random_rotate_cubes(-10,10,200)

3. Sample code

Create a function that randomly determines the color

○ Place colorful cubes at random positions and at random angles.

import bpy
import math
import numpy as np

#Definition of the function that determines the material
def material(name = 'material'):
    material_glass = bpy.data.materials.new(name)
    #Make the node available
    material_glass.use_nodes = True
    p_BSDF = material_glass.node_tree.nodes["Principled BSDF"]
    #0→BaseColor/7→roughness(=Roughness)/15→transmission(=propagation)
    #default_value = (R, G, B, A)
    p_BSDF.inputs[0].default_value = np.random.rand(4)
    p_BSDF.inputs[7].default_value = 0
    p_BSDF.inputs[15].default_value = 1
    #Add a material element to an object
    bpy.context.object.data.materials.append(material_glass)

#Definition of a function to generate three random values
def get_random_location(min,max):
    return (max - min) * np.random.rand(3) + min

#random_number()Definition of a function that rotates and makes a cube appear using the value generated by the function
def generate_random_rotate_cube(min,max):
    random_location = get_random_location(min,max)
    bpy.ops.mesh.primitive_cube_add(location = random_location,rotation = math.pi * np.random.rand(3))

#Definition of a function that rotates and makes multiple cubes appear at random positions
def generate_random_rotate_colorful_cubes(min,max,num):
    for i in range(0,num):
        generate_random_rotate_cube(min,max)
        material('Random')


generate_random_rotate_colorful_cubes(-10,10,200)

    

Create a function that arranges cubes while rotating them

import bpy
import math
import numpy as np

#Definition of the function that determines the material
def material(name = 'material'):
    material_glass = bpy.data.materials.new(name)
    #Make the node available
    material_glass.use_nodes = True
    p_BSDF = material_glass.node_tree.nodes["Principled BSDF"]
    #0→BaseColor/7→roughness(=Roughness)/15→transmission(=propagation)
    #default_value = (R, G, B, A)
    p_BSDF.inputs[0].default_value = np.random.rand(4)
    p_BSDF.inputs[7].default_value = 0
    p_BSDF.inputs[15].default_value = 1
    #Add a material element to an object
    bpy.context.object.data.materials.append(material_glass)

#Definition of a function that arranges colorful cubes while rotating them
def spiral_colorful_cubes():
    #Iterate 100 times
    for i in range(0,100):
        bpy.ops.mesh.primitive_cube_add(
            #Move up little by little
            location=(0, 0, i/50),
            scale=(1, 1, 0.05),
            #180 * i * 36(Every time)Shift one by one
            rotation = (0, 0, math.pi*i*10/360)
            )
        #Add a material element to an object
        material('Random')

#Execute the process
spiral_colorful_cubes()

Create a function that transforms the torus, rotates it, and arranges it

import bpy
import math
import numpy as np

#Definition of the function that determines the material
def material(name = 'material'):
    material_glass = bpy.data.materials.new(name)
    #Make the node available
    material_glass.use_nodes = True
    p_BSDF = material_glass.node_tree.nodes["Principled BSDF"]
    #0→BaseColor/7→roughness(=Roughness)/15→transmission(=propagation)
    #default_value = (R, G, B, A)
    p_BSDF.inputs[0].default_value = np.random.rand(4)
    p_BSDF.inputs[7].default_value = 0
    p_BSDF.inputs[15].default_value = 1
    #Add a material element to an object
    bpy.context.object.data.materials.append(material_glass)

#Definition of a function that transforms and shifts the torus and colors each
def colorful_torus_spiral():
    for i in range(0,36):
        bpy.ops.mesh.primitive_torus_add(
            location=(0, 0, 0),
            major_radius=1.0,
            minor_radius=0.01,
            )
        #Shrink in the Y-axis direction
        bpy.ops.transform.resize(value=(1, 0.3, 1))
        #Rotate around the Z axis
        bpy.ops.transform.rotate(value=math.pi*i*10/360,orient_axis='Z')
        #Add a material element to an object
        material('Random')

colorful_torus_spiral()

4. English words

Reference material

Reference: Automatically generate a large amount of particle live material with Blender x Python