Struct FieldConfig 

pub struct FieldConfig {
    pub resolution: u32,
    pub world_extent: f32,
    pub decay: f32,
    pub blur: f32,
    pub blur_iterations: u32,
    pub field_type: FieldType,
    pub custom_update: Option<String>,
}

Configuration for a 3D spatial field.

Fields are 3D grids that particles can read from and write to. Each frame, the field is processed: blur (diffusion), then decay. Optionally, custom WGSL code can replace the default blur/decay behavior.

Fields

resolution: u32

Grid resolution per axis (total cells = resolution³). Higher = more detail but more memory. Typical: 32, 64, 128.

world_extent: f32

World-space extent of the field (cube from -extent to +extent). Should match or exceed your simulation bounds.

decay: f32

Per-frame decay multiplier (0.0-1.0). 0.98 = slow decay, 0.5 = fast decay, 1.0 = no decay.

blur: f32

Blur strength per frame (0.0-1.0). Controls diffusion rate. 0.0 = no blur, 1.0 = max blur.

blur_iterations: u32

Number of blur iterations per frame. More iterations = smoother but more expensive.

field_type: FieldType

Type of field (Scalar or Vector).

custom_update: Option<String>

Custom WGSL code for field updates (replaces blur/decay if set).

Available variables:

• cell_idx: u32 - Linear index of current cell
• pos: vec3<u32> - Grid position (x, y, z)
• world_pos: vec3<f32> - World-space position
• value: f32 (scalar) or value: vec3<f32> (vector) - Current cell value
• params.resolution, params.extent, params.decay, params.blur
• uniforms.time, uniforms.delta_time

Helper functions:

• read_neighbor(dx: i32, dy: i32, dz: i32) -> f32/vec3<f32> - Read neighbor cell
• idx_3d(x, y, z) -> u32 - Convert 3D coords to linear index

Output: Write to new_value (same type as value)

Example (reaction-diffusion):

let lap = read_neighbor(-1,0,0) + read_neighbor(1,0,0)
        + read_neighbor(0,-1,0) + read_neighbor(0,1,0)
        + read_neighbor(0,0,-1) + read_neighbor(0,0,1) - 6.0 * value;
new_value = value + lap * 0.1 * uniforms.delta_time;

Implementations

impl FieldConfig

pub fn new(resolution: u32) -> Self

Create a new field configuration with the given resolution.

Default values:

• world_extent: 1.0 (cube from -1 to +1)
• decay: 0.99 (slow decay)
• blur: 0.1 (light diffusion)
• blur_iterations: 1

Memory Usage

• 32³ = 128KB
• 64³ = 1MB
• 128³ = 8MB

Example

let field = FieldConfig::new(64);

pub fn new_vector(resolution: u32) -> Self

Create a vector field configuration.

Vector fields store a vec3<f32> per cell instead of a scalar. Use for velocity fields, force fields, or flow visualization.

Memory Usage (3x scalar fields)

• 32³ = 384KB
• 64³ = 3MB
• 128³ = 24MB

pub fn vector(self) -> Self

Convert this field to a vector field.

Vector fields store vec3<f32> per cell for velocity/force data.

pub fn with_extent(self, extent: f32) -> Self

Set the world-space extent of the field.

The field covers a cube from -extent to +extent on all axes. Should match or exceed your simulation bounds.

pub fn with_decay(self, decay: f32) -> Self

Set the decay rate (0.0-1.0).

Applied each frame: field *= decay

• 1.0 = no decay (field persists forever)
• 0.99 = slow decay
• 0.9 = fast decay
• 0.0 = instant decay (field clears each frame)

pub fn with_blur(self, blur: f32) -> Self

Set the blur/diffusion strength (0.0-1.0).

Controls how much values spread to neighboring cells each frame.

• 0.0 = no diffusion
• 0.1 = light spread
• 0.5 = heavy spread
• 1.0 = maximum diffusion

pub fn with_blur_iterations(self, iterations: u32) -> Self

Set the number of blur iterations per frame.

More iterations = smoother diffusion but more expensive. Usually 1-3 is sufficient.

pub fn with_custom_update(self, code: impl Into<String>) -> Self

Set custom WGSL code for field updates.

When set, replaces the default blur/decay behavior with custom logic. See FieldConfig::custom_update for available variables and helpers.

Example

FieldConfig::new(64)
    .with_custom_update(r#"
        // Simple diffusion with custom decay
        let lap = read_neighbor(-1,0,0) + read_neighbor(1,0,0)
                + read_neighbor(0,-1,0) + read_neighbor(0,1,0)
                + read_neighbor(0,0,-1) + read_neighbor(0,0,1) - 6.0 * value;
        new_value = (value + lap * 0.2) * 0.99;
    "#)

pub fn has_custom_update(&self) -> bool

Check if this field has custom update logic.

pub fn total_cells(&self) -> u32

Total number of cells in the field.

pub fn memory_size(&self) -> usize

Memory size in bytes (for the main field buffer).

pub fn is_vector(&self) -> bool

Whether this is a vector field.

Trait Implementations

impl Clone for FieldConfig

fn clone(&self) -> FieldConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FieldConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for FieldConfig

fn default() -> Self

Returns the “default value” for a type.