/** How a radial impulse fades from the blast center to its edge. */
export type RadialFalloff = "linear" | "quadratic" | "none";
/** A radial push: the impulse vector plus the 0..1 falloff sampled at the target. */
export interface RadialImpulse {
    /** Impulse along the first axis (direction × magnitude). */
    x: number;
    /** Impulse along the second axis (direction × magnitude). */
    y: number;
    /** Impulse magnitude = `power` × `falloff`. */
    magnitude: number;
    /** Falloff weight at the target, 1 at the center down to 0 at the radius. */
    falloff: number;
}
/** Options for {@link radialImpulse}. */
export interface RadialImpulseOptions {
    /** Falloff shape. Defaults to `"linear"` (`1 − d/r`). */
    falloff?: RadialFalloff;
}
/**
 * Point-source radial impulse pushing a `target` away from a blast `source`: full `power` at the center
 * fading to zero at `radius`. Returns `null` when the target sits at or beyond the radius (unaffected),
 * so callers can early-out. At the exact center the direction is zero. This is the explosion/knockback/
 * shockwave push — every arena game hand-rolled the distance, falloff, and normalize.
 */
export declare function radialImpulse(source: readonly [number, number], target: readonly [number, number], radius: number, power: number, options?: RadialImpulseOptions): RadialImpulse | null;