@woosh/meep-engine/src/engine/graphics/camera/camera_compute_distance_to_fit_length.js

Pure JavaScript game engine. Fully featured and production ready.

import { assert } from "../../../core/assert.js";

/**
 * Compute camera distance offset in order to fit a given length (height) into view completely
 * @param {number} length Height of the focus area in world space
 * @param {number} fov Field of View in radians
 * @returns {number}
 */
export function camera_compute_distance_to_fit_length(length, fov) {
    // @see https://docs.unity3d.com/Manual/FrustumSizeAtDistance.html

    assert.isNumber(length, 'length');
    assert.greaterThanOrEqual(length, 0, 'length < 0');

    assert.isNumber(fov, 'fov');
    assert.greaterThan(fov, 0, 'fov <= 0');
    assert.lessThan(fov, Math.PI, 'fov >= pi');

    const signed_distance = (length * 0.5) / Math.tan(fov * 0.5);

    return Math.abs(signed_distance);
}