import { Mesh } from 'three';
import type { PerspectiveCamera, Texture } from 'three';
import type { StereoMode } from '@vizor-vr/shared';
import type { IProjection } from './projection.js';
/**
 * Equi-Angular Cubemap (EAC) projection for 3x2 atlas cubemap content.
 * Uses the same box geometry and UV atlas layout as CubemapProjection,
 * but applies a ShaderMaterial with tan() angular correction in the
 * fragment shader to correct for the equi-angular sampling distortion.
 *
 * For stereo content, creates two boxes on different Three.js layers
 * with UV remapping for side-by-side or top-bottom layouts.
 */
export declare class EacProjection implements IProjection {
    private meshes;
    createMeshes(texture: Texture, stereoMode: StereoMode): Mesh[];
    configureCamera(camera: PerspectiveCamera): void;
    update(_camera: PerspectiveCamera, _time: number): void;
    dispose(): void;
    private createBox;
    /**
     * Provide each face's atlas tile as a per-vertex `faceRegion` attribute
     * (xy = tile origin, zw = tile size), leaving geometry.uv as the default
     * face-local [0,1] coordinates. The fragment shader applies the equi-angular
     * correction in that face-local space and then maps the result into the tile
     * — applying the correction in atlas space (the previous approach) is wrong
     * because the tan() distortion is per-face.
     *
     * BoxGeometry has 6 faces, each with 4 vertices (indices face*4 .. face*4+3).
     * For TB stereo the atlas occupies the top or bottom half of the texture (V
     * compressed/offset); for SBS, the left or right half (U compressed/offset).
     */
    private setupFaceAtlas;
}
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