import type { TSLBoolInput, TSLFunction, TSLMat4Node, TSLVec3Node, TSLVec4Node } from '../types/tsl.cjs';
export interface BillboardingConfig {
    position?: TSLVec3Node | null | undefined;
    horizontal?: TSLBoolInput | undefined;
    vertical?: TSLBoolInput | undefined;
    worldMatrixNode?: TSLMat4Node | undefined;
}
export interface WorldUpBillboardingConfig {
    up?: TSLVec3Node | undefined;
    position?: TSLVec3Node | null | undefined;
    worldMatrixNode?: TSLMat4Node | undefined;
}
export interface BillboardingFunction extends TSLFunction<[config: BillboardingConfig], TSLVec4Node> {
    (): TSLVec4Node;
}
export interface WorldUpBillboardingFunction extends TSLFunction<[config: WorldUpBillboardingConfig], TSLVec4Node> {
    (): TSLVec4Node;
}
/**
 * This can be used to achieve a billboarding behavior for flat meshes. That means they are
 * oriented always towards the camera.
 *
 * ```js
 * material.vertexNode = billboarding();
 * ```
 *
 * @tsl
 * @function
 * @param {Object} config - The configuration object.
 * @param {?Node<vec3>} [config.position=null] - Can be used to define the vertex positions in world space.
 * @param {boolean} [config.horizontal=true] - Whether to follow the camera rotation horizontally or not.
 * @param {boolean} [config.vertical=false] - Whether to follow the camera rotation vertically or not.
 * @return {Node<vec3>} The updated vertex position in clip space.
 */
export declare const billboarding: BillboardingFunction;
/**
 * Billboard that preserves world up (no camera roll).
 * Useful for impostors where the atlas already encodes view direction.
 *
 * @tsl
 * @function
 * @param {Object} [config]
 * @param {Node<vec3>} [config.up=vec3(0,1,0)] - World up direction.
 * @param {Node<vec3>} [config.position=null] - Optional world-space position override.
 * @param {Node<mat4>} [config.worldMatrixNode=modelWorldMatrix] - World transform for scale.
 * @return {Node<vec3>} The updated vertex position in clip space.
 */
export declare const worldUpBillboarding: WorldUpBillboardingFunction;