import { Expr, GpuFragmentParams } from '../../gpu/contract';
import { PropRef } from '../values';

export interface GridSlots {
    columns: PropRef;
    rows: PropRef;
    gapX: PropRef;
    gapY: PropRef;
    stagger: PropRef;
    /** Structural: alternate-mirror mode ('none' | flip-x | flip-y | both). */
    flip: PropRef;
}
export interface RadialSlots {
    count: PropRef;
    radius: PropRef;
    startAngle: PropRef;
    sweep: PropRef;
    faceCenter: PropRef;
}
export interface LineSlots {
    count: PropRef;
    direction: PropRef;
    spacing: PropRef;
}
export type PlacementSpec = {
    kind: 'grid';
    slots: GridSlots;
} | {
    kind: 'radial';
    slots: RadialSlots;
} | {
    kind: 'line';
    slots: LineSlots;
};
export declare const grid: (slots: GridSlots) => PlacementSpec;
export declare const radial: (slots: RadialSlots) => PlacementSpec;
export declare const line: (slots: LineSlots) => PlacementSpec;
/** Pick a placement member by a structural mode prop — only the active member emits. */
export interface PlacementPick {
    mode: PropRef;
    members: {
        grid: PlacementSpec;
        radial: PlacementSpec;
        linear: PlacementSpec;
    };
}
export declare const byMode: (mode: PropRef, members: PlacementPick["members"]) => PlacementPick;
export interface VariationSlots {
    scale: PropRef;
    rotation: PropRef;
    opacity: PropRef;
    jitter: {
        position: PropRef;
        rotation: PropRef;
        scale: PropRef;
        opacity: PropRef;
    };
    seed: PropRef;
    /** Seamless layout animation phase (wraps at 1). */
    phase: PropRef;
}
export interface RepeatInstancesRecipe {
    /** Crop insets applied to the sampled source rect. */
    source: {
        crop: {
            left: PropRef;
            right: PropRef;
            top: PropRef;
            bottom: PropRef;
        };
    };
    placement: PlacementPick | PlacementSpec;
    variation: VariationSlots;
    /** Per-instance hue rotation (radians/instance); active when the prop is non-zero. */
    hueShift?: PropRef;
    /** Structural stacking order ('forward' | 'backward'). */
    order: PropRef;
}
/**
 * Build the instance-repeat fragment: placement frame → per-instance variation
 * (→ hue-shift stage) → premultiplied over-accumulation of the child sampled per instance.
 */
export declare function repeatInstances(recipe: RepeatInstancesRecipe): (params: GpuFragmentParams) => Expr;
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