Logic, variables and utility

Every example on this page runs after these two lines, and ends by sending a color to the Output node:

from pyzed import shading

g = shading.Graph("demo")

Logic

True/false values and choosing between two values. Shaders run on every pixel at once, so prefer Mix and Smoothstep for soft transitions and keep Select for hard either/or choices.

Compare

compare · Logic · g.compare(...)

Whether a is less, greater or equal to b (for vectors: every component).

Compares a and b (<, <=, >, >=, ==, !=) and gives true or false.

Input	Type	Default
a	T	0
b	T	0.5

Output	Type
result	bool

Setting	Values	Default
op	<, <=, >, >=, ==, !=	<

Example

left = g.compare(g.uv()["x"], 0.5, op="<")
g.output(g.rgba(g.select(left, 1.0, 0.2), 1.0))

Select

select · Logic · g.select(...)

if condition then a else b.

If condition is true, a (then); otherwise b (else).

Input	Type	Default
condition	bool	true
a · then	T	1
b · else	T	0

Output	Type
result	T

Example

inside = g.mouse()["inside"]
g.output(g.rgba(g.select(inside, [0.2, 0.8, 0.4], [0.3, 0.3, 0.3]), 1.0))

Logic

logic · Logic · g.logic(...)

and, or, xor and not of true/false values.

and, or, xor and not of true/false values.

Input	Type	Default
a	bool	true
b	bool	false

Output	Type
result	bool

Setting	Values	Default
op	and, or, xor, not	and

Example

uv = g.uv()
both = g.logic(g.compare(uv["x"], 0.5, op=">"), g.compare(uv["y"], 0.5, op=">"), op="and")
g.output(g.rgba(g.select(both, 1.0, 0.0), 1.0))

Variables

Named values inside the graph: compute something once, name it, and read it anywhere without a long wire across the canvas.

Set value

set_var · Variables · g.set_var(...)

Gives a value a name, so Get value nodes can read it anywhere without a long wire.

Gives a value a name. Any Get value with the same name reads it, so you can reuse it far away without a wire crossing the whole canvas.

Input	Type	Default
value	T	0

Output	Type
value	T

Setting	Values	Default
name	text	value1

Example

g.set_var(g.noise(scale=4.0), name="n")
n = g.get_var(name="n")
g.output(g.rgba(g.palette(n), 1.0))

Get value

get_var · Variables · g.get_var(...)

Reads a value named by a Set value node.

Reads a value named by a Set value node.

Output	Type
value	T

Setting	Values	Default
name	local	value1

Example

g.set_var(g.uv()["x"], name="x")
g.output(g.gradient(g.get_var(name="x")))

Utility

Nodes that keep big graphs tidy and let you go beyond the catalog.

Reroute

reroute · Utility · g.reroute(...)

A point to bend a wire around other nodes.

A dot that only bends a wire around other nodes: it changes nothing.

Input	Type	Default
in	T	0

Output	Type
out	T

Example

x = g.reroute(g.uv()["x"])
g.output(g.gradient(x))

Expression

expression · Utility · g.expression(...)

Your own WGSL: an expression of a, b, c and d (and uv, px, size, time), or a function body with return. The types of a to d follow what is connected.

Your own line of WGSL when no node does what you need: an expression of a, b, c and d (plus uv, px, size and time), or a function body with return. Pick the result’s type.

Input	Type	Default
a	any	0
b	any	0
c	any	0
d	any	0

Output	Type
result	float

Setting	Values	Default
code	code	a + b
type	float, vec2, vec3, vec4, int, bool	float

The types of a to d follow what is wired to them (any); type sets the result’s.

Example

e = g.expression(g.uv()["x"], 8.0, code="abs(sin(a * b + time))", type="float")
g.output(g.rgba(e, 1.0))

Shader function

subgraph · Utility · g.subgraph(...)

Another .pzshad used as a function: its mutable variables are inputs, its output is the color. Feed uv to move, tile or warp it.

Uses another .pzshad as a function: its mutable variables become inputs and its color the output. Feed uv to move, tile or warp the whole shader.

Input	Type	Default
uv	vec2	UV (context)

Output	Type
color	vec4
rgb	vec3
alpha	float

Setting	Values	Default
path	file	—

Besides uv, every mutable variable of the other shader becomes an input.

A Shader function needs another .pzshad file: g.subgraph(path="plasma.pzshad", uv=...). In the designer, double-click the node to open that file.

Comment

comment · Utility · g.comment(...)

A note on the graph.

A note on the canvas to explain a part of the graph. It has no effect on the shader.

Setting	Values	Default
text	text	Note

Example

g.comment(text="Sky: gradient from top to bottom")
g.output(g.gradient(g.uv()["y"]))

Output

Every shader has one Output node: what reaches it is the color of the pixel.

Output

output · Output · g.output(...)

The color of every pixel. Alpha, when connected, replaces color’s alpha.

The end of the graph: the color it receives is the color of the pixel. If alpha is connected it replaces the color’s alpha. g.output(color) adds or finds it in Python.

Input	Type	Default
color	vec4	(0, 0, 0, 1)
alpha	float	— (not used until connected)

Example

g.output([1.0, 0.4, 0.1, 1.0], alpha=g.radial_gradient(radius=0.5))

Always up to date

This page is generated from the node catalog of pyzed.shading, so the ports, types and defaults are always those of this version. Each example is compiled when the docs are built.

See also: Getting started · The Shader view · Recipes · Shader graphs in Python