/**
 * DepthState is a descriptor that defines how the depth value of the fragment is used by the
 * rendering pipeline. A depth state can be set on a material using {@link Material#depthState},
 * or in some cases on the graphics device using {@link GraphicsDevice#setDepthState}.
 *
 * For the best performance, do not modify depth state after it has been created, but create
 * multiple depth states and assign them to the material or graphics device as needed.
 *
 * @category Graphics
 */
export class DepthState {
    /**
     * A default depth state that has the depth testing function set to {@link FUNC_LESSEQUAL} and
     * depth writes enabled.
     *
     * @type {DepthState}
     * @readonly
     */
    static readonly DEFAULT: DepthState;
    /**
     * A depth state that always passes the fragment but does not write depth to the depth buffer.
     *
     * @type {DepthState}
     * @readonly
     */
    static readonly NODEPTH: DepthState;
    /**
     * A depth state that always passes the fragment and writes depth to the depth buffer.
     *
     * @type {DepthState}
     * @readonly
     */
    static readonly WRITEDEPTH: DepthState;
    /**
     * Create a new Depth State instance.
     *
     * @param {number} func - Controls how the depth of the fragment is compared against the
     * current depth contained in the depth buffer. See {@link DepthState#func} for details.
     * Defaults to {@link FUNC_LESSEQUAL}.
     * @param {boolean} write - If true, depth values are written to the depth buffer of the
     * currently active render target. Defaults to true.
     */
    constructor(func?: number, write?: boolean);
    /**
     * Bit field representing the depth state.
     *
     * @private
     */
    private data;
    _depthBias: number;
    _depthBiasSlope: number;
    /**
     * A unique number representing the depth state. You can use this number to quickly compare
     * two depth states for equality. The key is always maintained valid without a dirty flag,
     * to avoid condition check at runtime, considering these change rarely.
     *
     * @type {number}
     */
    key: number;
    /**
     * Sets the depth testing function. Controls how the depth of the fragment is compared against
     * the current depth contained in the depth buffer. Can be:
     *
     * - {@link FUNC_NEVER}: don't draw
     * - {@link FUNC_LESS}: draw if new depth < depth buffer
     * - {@link FUNC_EQUAL}: draw if new depth == depth buffer
     * - {@link FUNC_LESSEQUAL}: draw if new depth <= depth buffer
     * - {@link FUNC_GREATER}: draw if new depth > depth buffer
     * - {@link FUNC_NOTEQUAL}: draw if new depth != depth buffer
     * - {@link FUNC_GREATEREQUAL}: draw if new depth >= depth buffer
     * - {@link FUNC_ALWAYS}: always draw
     *
     * @type {number}
     */
    set func(value: number);
    /**
     * Gets the depth testing function.
     *
     * @type {number}
     */
    get func(): number;
    /**
     * Sets whether depth writing is performed. If true, shader write a depth value to the depth
     * buffer of the currently active render target. If false, no depth value is written.
     *
     * @type {boolean}
     */
    set write(value: boolean);
    /**
     * Gets whether depth writing is performed.
     *
     * @type {boolean}
     */
    get write(): boolean;
    /**
     * Sets whether depth testing is performed. If true, a shader fragment is only written to the
     * current render target if it passes the depth test. If false, it is written regardless of
     * what is in the depth buffer. Note that when depth testing is disabled, writes to the depth
     * buffer are also disabled. Defaults to true.
     *
     * @type {boolean}
     */
    set test(value: boolean);
    /**
     * Gets whether depth testing is performed.
     *
     * @type {boolean}
     */
    get test(): boolean;
    /**
     * Sets the constant depth bias added to each fragment's depth. Useful for decals to prevent
     * z-fighting. Typically a small negative value (-0.1) is used to render the mesh slightly
     * closer to the camera. Defaults to 0.
     *
     * @type {number}
     */
    set depthBias(value: number);
    /**
     * Gets the constant depth bias added to each fragment's depth.
     *
     * @type {number}
     */
    get depthBias(): number;
    /**
     * Sets the depth bias that scales with the fragment's slope. Defaults to 0.
     *
     * @type {number}
     */
    set depthBiasSlope(value: number);
    /**
     * Gets the depth bias that scales with the fragment's slope.
     *
     * @type {number}
     */
    get depthBiasSlope(): number;
    /**
     * Copies the contents of a source depth state to this depth state.
     *
     * @param {DepthState} rhs - A depth state to copy from.
     * @returns {DepthState} Self for chaining.
     */
    copy(rhs: DepthState): DepthState;
    /**
     * Returns an identical copy of the specified depth state.
     *
     * @returns {this} The result of the cloning.
     */
    clone(): this;
    updateKey(): void;
    /**
     * Reports whether two DepthStates are equal.
     *
     * @param {DepthState} rhs - The depth state to compare to.
     * @returns {boolean} True if the depth states are equal and false otherwise.
     */
    equals(rhs: DepthState): boolean;
}