import type { ColorKeyframe, CurveKeyframe, ParticleCurve } from '@flighthq/types/contract';
/** Bake an RGB function f:[0,1]→[r,g,b] into an interleaved curve LUT (length N×3). */
export declare function buildParticleColorCurve(f: (t: number) => readonly [number, number, number], samples?: number): number[];
/** Bake a scalar function f:[0,1]→value into an `samples`-entry curve LUT. */
export declare function buildParticleCurve(f: (t: number) => number, samples?: number): number[];
/** Linearly interpolate two sRGB colors through HSV space, writing into `out[offset..+3]`.
 *  Used by the `colorInterpolation: 'hsv'` path in updateParticleEmitter2D. */
export declare function lerpHsvDirect(out: Float32Array | number[], offset: number, r0: number, g0: number, b0: number, r1: number, g1: number, b1: number, t: number): void;
/** Interpolate through HSV space using per-particle birth/death color arrays. */
export declare function lerpHsvInPlace(colorsOut: Float32Array | number[], offset: number, birth: Float32Array, death: Float32Array, t: number): void;
/** Bake a piecewise-linear RGB timeline (e.g. an imported color gradient) into a
 *  uniform interleaved LUT (length N×3). */
export declare function particleColorCurveFromKeyframes(keys: ReadonlyArray<ColorKeyframe>, samples?: number): number[];
/** Convert a baked interleaved RGB curve LUT (length N×3) back into color
 *  keyframes (one per sample, at uniform times). */
export declare function particleColorCurveToKeyframes(lut: ParticleCurve): ColorKeyframe[];
/** Bake a piecewise-linear scalar timeline (e.g. an imported alpha-over-lifetime
 *  curve) into a uniform LUT. Keyframes need not be sorted; times are clamped to
 *  the [first, last] range. */
export declare function particleCurveFromKeyframes(keys: ReadonlyArray<CurveKeyframe>, samples?: number): number[];
/** Convert a baked scalar curve LUT back into keyframes (one per sample, at
 *  uniform times). The inverse of {@link particleCurveFromKeyframes} for the common case
 *  of a 33-sample LUT — used by format serializers to round-trip authored curves. */
export declare function particleCurveToKeyframes(lut: ParticleCurve): CurveKeyframe[];
/** Sample an interleaved RGB curve (length N×3) at t∈[0,1], writing the three
 *  channels into `out` starting at `offset`. */
export declare function sampleParticleColorCurve(out: {
    [index: number]: number;
}, offset: number, lut: ParticleCurve, t: number): void;
/** Sample a uniformly-spaced scalar curve at t∈[0,1] with linear interpolation.
 *  Out-of-range t is clamped. An empty curve samples to 0; a single value is
 *  returned as-is. */
export declare function sampleParticleCurve(lut: ParticleCurve, t: number): number;
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