Class MPMReference

constructor

• new MPMReference(
      input?: {
          capacity?: number;
          cellSize?: number;
          cfl?: number;
          friction?: number;
          gravity?: [number, number, number];
          materials?: {
              [key: string]: { [key: string]: number | undefined } | undefined;
          };
          maxSpeed?: number;
          maxSubsteps?: number;
          origin?: [number, number, number];
          render?: {
              colors?: string[];
              opacity?: number;
              size?: number;
              strainScale?: number;
          };
          resolution?: [number, number, number];
          seed?: string | number;
          substeps?: number;
          walls?: boolean;
      },
      height?: MPMHeightFn | null,
  ): MPMReference

  A reference solver with capacity particle slots; height is the terrain (none by default).

  Parameters

  • input: {
        capacity?: number;
        cellSize?: number;
        cfl?: number;
        friction?: number;
        gravity?: [number, number, number];
        materials?: {
            [key: string]: { [key: string]: number | undefined } | undefined;
        };
        maxSpeed?: number;
        maxSubsteps?: number;
        origin?: [number, number, number];
        render?: {
            colors?: string[];
            opacity?: number;
            size?: number;
            strainScale?: number;
        };
        resolution?: [number, number, number];
        seed?: string | number;
        substeps?: number;
        walls?: boolean;
    } = {}

    • Optionalcapacity?: number

      Most particles. Fixed at construction.

    • OptionalcellSize?: number

      Grid spacing Δx, metres. Particles are emitted 2 per cell per axis (8 per cell). Fixed at construction.

    • Optionalcfl?: number

      Courant number C of the stable step dt ≤ C·Δx / (maxSpeed + sound speed) (see mpmStableStep).

    • Optionalfriction?: number

      Terrain friction coefficient (Coulomb): 0 slips, large values stick.

    • Optionalgravity?: [number, number, number]

      Gravity, m/s².

    • Optionalmaterials?: { [key: string]: { [key: string]: number | undefined } | undefined }

      Materials compiled in (keys, fixed at construction) and their parameters (live).

    • OptionalmaxSpeed?: number

      Particle speed limit, m/s: the "max particle speed" of the stable step, enforced in G2P.

    • OptionalmaxSubsteps?: number

      Most substeps per frame; past it the simulation runs slower than real time instead of going unstable.

    • Optionalorigin?: [number, number, number]

      World position of the domain's minimum corner, metres. Moving it shifts the domain by whole cells (the particles keep their world positions; those left outside freeze). Floating-origin safe: the GPU only sees positions relative to it.

    • Optionalrender?: { colors?: string[]; opacity?: number; size?: number; strainScale?: number }

      Drawing through the particle pool's unlit shading.

      • Optionalcolors?: string[]

        Colour ramp by volume change J: first key squashed, middle at rest, last stretched (1 to 8 #rrggbb).

      • Optionalopacity?: number

        Opacity.

      • Optionalsize?: number

        Sprite width, in particle spacings (Δx / 2).

      • OptionalstrainScale?: number

        How much volume change spans the colour ramp: key = 0.5 + (J − 1) × strainScale.

    • Optionalresolution?: [number, number, number]

      Grid nodes along x, y, z (8…160 each). Fixed at construction.

    • Optionalseed?: string | number

      Seed for the emission jitter.

    • Optionalsubsteps?: number

      Substeps per frame at least. More are added when the frame is longer than the stable step allows.

    • Optionalwalls?: boolean

      Domain sides act as slip walls (else particles that leave the domain freeze).

  • height: MPMHeightFn | null = null

  Returns MPMReference

colliders

Readonlydata

ReadonlyfrictionMap

Readonlygrid

Readonlyheights

Readonlymaterials

Readonlyoptions

time

emit

• emit(spec: MPMEmit): number

  Adds a block of particles (see MPMEmit); returns how many (stops at capacity).

  Parameters

  • spec: MPMEmit

  Returns number

mass

• mass(): number

  Total particle mass, kg.

  Returns number

momentum

• momentum(): [number, number, number]

  Total particle momentum, kg·m/s.

  Returns [number, number, number]

setFriction

• setFriction(friction: MPMFrictionFn | null): this

  Scales the terrain friction by friction(x, z) per node column, as MPMSolver.setFriction; null for 1.

  Parameters

  • friction: MPMFrictionFn | null

  Returns this

step

• step(frameDt: number): number

  Advances a frame of frameDt seconds in substeps (see mpmTimeStep); returns the substeps.

  Parameters

  • frameDt: number

  Returns number

substep

• substep(dt: number): void

  One P2G → grid → G2P substep of dt seconds.

  Parameters

  • dt: number

  Returns void