Particle Materials

Materials define the appearance of particles and how they interact with lights. The material of a particle type can be set in the Visual tab in the Properties window. Most materials offer additional material parameters like a texture or an emission color, which can be set by clicking next to the material property. Pixelpart has several built-in materials but you can also define custom materials using shader graphs.

Built-in materials

Pixelpart’s built-in materials are suitable for a variety of circumstances and most of the time you do not need to create custom materials. The built-in materials provide support for texturing, sprite sheet animation, lighting, soft particles and more. Depending on the renderer you have selected for a particle type, you can choose from different built-in materials.

Sprite materials

The following materials are available for Sprite particles.

Material	Description
SpriteUnlitAlpha	For rendering alpha-blended sprite particles without lighting.
SpriteUnlitAdditive	For rendering additively blended sprite particles without lighting.
SpriteLitAlpha	For rendering alpha-blended sprite particles with lighting.
SpriteLitAdditive	For rendering additively blended sprite particles with lighting.

All of these materials provide support for sprite sheet animation, soft particles and distance fade.

Trail materials

The following materials are available for Trail particles.

Material	Description
TrailUnlitAlpha	For rendering alpha-blended trail particles without lighting.
TrailUnlitAdditive	For rendering additively blended trail particles without lighting.
TrailLitAlpha	For rendering alpha-blended trail particles with lighting.
TrailLitAdditive	For rendering additively blended trail particles with lighting.

All of these materials provide support for soft particles and distance fade.

Mesh materials

The following materials are available for Mesh particles.

Material	Description
MeshUnlit	For rendering opaque mesh particles without lighting.
MeshUnlitAlpha	For rendering alpha-blended mesh particles without lighting.
MeshLit	For rendering opaque mesh particles with lighting.
MeshLitAlpha	For rendering alpha-blended mesh particles with lighting.

Custom materials

Warning

Custom materials are not fully supported across all game engine plugins. Stick to built-in materials to make sure particles are rendered correctly in all engines.

To start creating a custom material for a particle type, select the New option in the material drop-down menu of the particle type and then click next to the material property, which opens the Material editor.

Custom material are designed with shader graphs allowing you to define the material of particles more precisely. Such a shader graph consists of nodes that work together to define the final pixel color. Each nodes implements a specific function that computes an output value from its input values, which are supplied by other nodes. Some nodes also have additional parameters that influence their function.

One example is the Blend node, which mixes two colors together: The two colors are connected to the input pins of the node while the output pin, carrying the resulting color, is connected to other nodes in the graph. The parameter Mode determines how the colors are blended together.

Eventually, all nodes run together into the Output node, which sets the final color of each pixel. Color values are stored in RGBA (Red, Green, Blue, Alpha) format, where each channel contains a number in the range [0, 1] defining the color intensity for that channel. The alpha component defines the opacity. The node also has inputs for an emission color, as well as a roughness and metallic values used during shading of the particle in the presence of light.

Inside the Output node you also set the blend mode and lighting mode of the material. The blend mode determines how particles are blended together and are composed with other objects in the effect.

• Off: Particles are not blended together and occlude each other.

• Normal: Particles are blended together based on their opacity.

• Additive: Particle colors are added together.

• Subtractive: Particle colors are subtracted from each other.

The lighting mode determines whether the material is shaded by lights in the scene.

• Unlit: The material is not shaded based on lighting.

• Lit: The material is shaded based on lighting.

Creating shader graphs

By default, a custom material already has a default shader graph, which applies a texture and combines it with the color set in the particle properties. To assign a completely new material click New or select a preset from the drop-down menu. The name of the material can be set in the input field in the toolbar.

New nodes can be added by right-clicking an empty space and selecting a node type, by dragging out an attribute pin and dropping it on an empty space or by clicking Add in the toolbar. The list of available nodes can be filtered by typing in the search box at the top.

While right-clicking or dragging out a node pin, there are several keyboard shortcuts for creating common node types directly.

Shortcut	Node
1	Number
2	Vector 2
3	Vector 3
4	Vector 4
B	Boolean
I	Integer
C	Color

After adding a new node, connect its input and output pins to the rest of the graph by dragging out links from each pin. The pin color and shape denote the data type that is expected for the attribute. For example, the red color denotes a 4-component vector, which is used for color values. Most of the time, different data types can be converted into one another.

To remove a node, click Remove in the context menu of the node or select the node(s) and press Remove in the tool bar.

In order to apply your changes to the material, click Apply in the toolbar. Otherwise, they are discarded when you close the window.

Saving and loading materials

You can save a custom material to a .ppmt file, which is useful for sharing materials across different effects. Click Save in the toolbar to select a location for the material file. An existing material file can be loaded using Load.

Available nodes

Constants

Node	Inputs	Description
Boolean		Boolean constant, which can be true or false.
Integer		Integer constant, which can be any positive or negative integer.
Number		Number constant, which can be any rational number.
Vector 2		Vector constant with two components.
Vector 3		Vector constant with three components.
Vector 4		Vector constant with four components.
Color		Color constant with four components (RGBA).

Inputs

Node	Inputs	Description
Input: Position (world space)		Vertex position in world space.
Input: Position (view space)		Vertex position in view space.
Input: Normal (world space)		Normal at the current pixel in world space.
Input: Normal (view space)		Normal at the current pixel in view space.
Input: Texture coordinate		Texture coordinate at the current pixel. Used to sample textures.
Input: Color		Color of the particle. This input can be set with the Color attribute in the Visuals tab.
Input: Velocity		Velocity vector of the particle.
Input: Life		Remaining life of the particle, from 1.0 (particle has just spawned) to 0.0 (particle is about to disappear).
Input: Object ID		ID of the current particle, which can be used to differentiate individual particles.
Effect time		Time passed since the effect has started.
Object time		Time passed since the particle emitter was instantiated.

Colors

Node	Inputs	Description
Blend	A, B	Blends colors A and B together using the specified blending mode.
Color ramp	Value	Picks a color from the specified gradient using Value as an index between 0.0 and 1.0.
Adjust brightness	Color, Brightness	Increases the brightness of Color for Brightness > 0 and decreases it for Brightness < 0.
Adjust exposure	Color, Exposure	Increases the exposure of Color for Exposure > 0 and decreases it for Exposure < 0.
Adjust contrast	Color, Contrast	Increases the contrast of Color for Contrast > 0 and decreases it for Contrast < 0.
Adjust saturation	Color, Saturation	Increases the saturation of Color for Saturation > 0 and decreases it for Saturation < 0.
Posterize	Color, Number	Reduces the number of available colors per channel to Number.

Textures

Node	Inputs	Description
Texture: Image	UV	Samples the given image at texture coordinate UV.
Texture: Sprite sheet	UV, Frame	Samples the sprite at index Frame in the given sprite sheet at texture coordinate UV.
Sprite sheet	UV, Frame, Frames / row, Frames / column	Calculates the corresponding texture coordinate for sampling a sprite sheet at index Frame.
Tiling and offset	UV, Tiling, Offset	Transforms texture coordinate UV by tiling it Tiling times and applying Offset.
Twirl	UV, Amount	Transforms texture coordinate UV by twirling it with strength Amount.

Procedural

Node	Inputs	Description
Circle mask	UV, Radius, Smoothness	Generates a circular mask, where (0.5, 0.5) is the circle’s center, Radius is its radius and Smoothness dictates how slowly the value falls off outside the radius. The circle is then sampled at coordinate UV.
Noise (1D)	Position, Amplitude, Frequency, Persistence, Lacunarity	Generates 1D Simplex noise with the given parameters. This noise is sampled at coordinate Position.
Noise (2D)	Position, Amplitude, Frequency, Persistence, Lacunarity	Generates 2D Simplex noise with the given parameters. This noise is sampled at coordinate Position.

Math

Node	Inputs	Description
Add	A, B	Adds A and B (A + B).
Subtract	A, B	Subtracts B from A (A - B).
Multiply	A, B	Multiplies A with B (A * B).
Divide	A, B	Divides A by B (A / B).
Modulo	A, B	Computes the modulus of A and B (A mod B).
Power	A, B	Raises A to the power of B (A^B).
Natural exponentiation	Value	Computes the natural exponentiation of Value (exp(Value)).
Natural logarithm	Value	Computes the natural logarithm of Value (ln(Value)).
Sign	Value	Returns the sign of Value, i.e. +1 if Value is positive, -1 if Value is negative and 0 if Value is 0.
Absolute value	Value	Returns the absolute value of Value (|Value|).
Min	A, B	Returns the minimum of A and B (min(A, B)).
Max	A, B	Returns the maximum of A and B (max(A, B)).
Clamp	Value, Min, Max	Limits Value to the range [Min, Max].
Linear interpolation	A, B, Factor	Interpolations linearly between A and B using Factor (in the range [0, 1]).
Floor	Value	Rounds Value down to the next integer.
Ceil	Value	Rounds Value up to the next integer.
Round	Value	Rounds Value to the nearest integer.
Square root	Value	Computes the square root of Value.
Sin	Value	Computes the sine of Value.
Cos	Value	Computes the cosine of Value.
Arcsin	Value	Computes the arcus sine of Value.
Arccos	Value	Computes the arcus cosine of Value.
Dot product	A, B	Computes the dot product of vectors A and B.
Cross product	A, B	Computes the cross product of vectors A and B.
Normalize	Vector	Normalizes Vector to a vector of length 1.
Vector length	Vector	Returns the length or magnitude of Vector.
Step	Value, Edge	Generates a step function by comparing Value to Edge. If Value < Edge, the output is 0 and otherwise 1.
Smooth step	Value, Edge 1, Edge 2	Performs a smooth interpolation between 0 and 1 when Edge 1 < Value < Edge 2.
Threshold	Value	Returns parameter Output if Value is smaller than parameter Threshold.

Logic

Node	Inputs	Description
Negation (NOT)	Value	Negates the boolean Value.
Conjunction (AND)	A, B	Outputs true if and only if both A and B are true.
Disjunction (OR)	A, B	Outputs true if and only if A or B is true.
Exclusive disjunction (XOR)	A, B	Outputs true if and only if either A or B is true.
Branch	Predicate, True, False	Outputs the value for True if Predicate evaluates to true and the value for False otherwise.

Comparison

Node	Inputs	Description
Equal	A, B	Outputs true if A = B and false otherwise.
Not equal	A, B	Outputs true if A ≠ B and false otherwise.
Approximately equal	A, B	Outputs true if A ≈ B (depending on given Epsilon) and false otherwise.
Less	A, B	Outputs true if A < B and false otherwise.
Less or equal	A, B	Outputs true if A ≤ B and false otherwise.
Greater	A, B	Outputs true if A > B and false otherwise.
Greater or equal	A, B	Outputs true if A ≥ B and false otherwise.

Utility

Node	Inputs	Description
Frame animation	Time, Duration, Frames, Start frame, Loop	Computes the frame (in a sprite sheet, for example) that has been reached after time Time. The animation is characterized by the other input parameters.
Soft-Particles	Transition	Calculates the blending factor for a soft particle effect at the current pixel with the given transition size.
Distance face	Value	Calculates the blending factor for a distance fade effect with the given transition size.
Value curve	Value	Defines a graph using keyframes and samples this graph at position Value.
Split vector (2)	Vector	Splits the two-dimensional vector Vector into its components.
Split vector (3)	Vector	Splits the three-dimensional vector Vector into its components.
Split vector (4)	Vector	Splits the four-dimensional vector Vector into its components.
Merge vector (2)	X, Y	Combines X, Y into a two-dimensional vector.
Merge vector (3)	X, Y, Z	Combines X, Y, Z into a three-dimensional vector.
Merge vector (4)	X, Y, Z, W	Combines X, Y, Z, W into a four-dimensional vector.