TSR_SpriteEnemy

 * ====================================================================
 * == About this Plugin ===============================================
 * ====================================================================
 * The plugin provide 4 battle motions for enemies:
 *
 *        Idle motion: When the enemy battler is in 'wait' mode.
 *
 *      Attack motion: When the enemy battler make a regular attack.
 *
 *       Skill motion: When the enemy battler execute a skill
 *
 *      Damage motion: When the enemy battler receive damages.
 *
 *
 * In addition, the plugin revamp some of the battle effects for enemy
 * battlers behaviors:
 *
 *     Attack and skill: the enemy battler will step forward, tilt a bit
 *                       while executing the action, and step back. This
 *                       replace the default 'whiten' effect.
 *
 *               Damage: the enemy battler will step back, tilt a bit
 *                       with a red flashing effect, and move back to
 *                       its position. This replace the default 'blink'
 *                       effect.
 *
 *                Evade: the enemy battler will step back as it evades an
 *                       attack, then move back to its position.
 *
 *               States: the plugin provide the option of using the state
 *                       overlays animation over enemy battlers when they
 *                       are affected by a state. You can choose to show
 *                       either the default state icons or the animated
 *                       overlays, or both. Overlays requires to be set
 *                       with enemies notetags (see bellow).
 *
 *          Restriction: the animated enemy battlers will freeze whenever
 *                       they are affected by a state that have the 'cannot
 *                       move' restriction.
 *
 *             *step forward and backward directions depends on wether
 *              side or front view is in use.
 *
 *
 * HOW TO USE:
 *
 *    The motions frames must be arranged in a sprite sheet with 4 rows.
 *    Each row represent one of the 4 battle motions, 'Idle', 'Attack',
 *    'Skill' and 'Damage', in that order.
 *
 *    The motions animations can have any number of frames, down to a
 *    minimum of 3. Each motion on a sprite sheet must have the same
 *    number of frames.
 *
 *    The 'Idle' motion is a back and forth loop. The other motions
 *    stops once the last frame is reached.
 *
 *    Use the following Enemy Notetag to assign a sprite sheet to an
 *    enemy in the database.
 *
 *      ENEMY NOTETAG:
 *                      <ENEMY IMAGE: filename, frames>
 *
 *              filename: the file name of the sprite sheet without
 *                        extension. The sprite sheet must be stored
 *                        in /img/sv_enemies (if using side-view) or
 *                        /img/enemies (if using front-view).
 *
 *                frames: the number of frame per motions of the
 *                        sprite sheet.
 *
 *     
 *                   EXAMPLE:  <ENEMY IMAGE: GobelinSheet, 3>
 *
 *
 *                   The enemy battler having this notetag will be
 *                   assigned with the sprite sheet 'GobelinSheet'
 *                   which have 4 rows of 3 frames motions.
 *
 *         
 *          Use this notetag to assign a specific animation to the
 *          normal attack of an enemy.
 *
 *                          <ATTACK ANIMATION: Id>
 *
 *                    Id: the id of the animation that will play when
 *                        the enemy execute a normal attack.
 *
 *
 *
 *      NOTES:
 * 
 *         *The sprite sheets are splitted by the plugin into 4 rows and
 *          a number of columns defined by the notetag 'frames' argument.
 *          This mean you can use sprite sheets of any size. The enemy
 *          images will appear at their actual size on the battlefield.
 *
 *         *Enemies without the notetag will be treated as the default
 *          static enemies.
 *
 *         *You can use a mix of animated enemies and static enemies.
 *
 *         *Static enemies will still behave according to the battle
 *          effects provided by the plugin.
 *
 *         *It is suggested to assign a static enemy image to enemies
 *          in the database even if they have a sprite sheet notetag.
 *          You can use the same image for all animated enemies, it
 *          will serve as a placeholder for building the troops.
 *
 *         *Be sure your sprite sheets are stored in the correct folder
 *          wether you're using side-view or front-view battles.
 *
 *
 * ENEMIES STATE OVERLAYS
 *
 *      Plugin parameters:
 *
 *           -Enable State Icons:
 *                  Display or not the default state icons above enemy
 *                  battlers head.
 *
 *           -Enable State Overlays:
 *                  Display or not the animated state overlays over enemy
 *                  battlers.
 *
 *      Animated state overlays are binded to the state affected battler,
 *      and appears at the center of the battler sprite, similar to the
 *      Actor battlers animated state overlays.
 *
 *      While actor battlers are all the same size, enemy battlers can
 *      have various size and forms. This means that the state overlays
 *      might not appears correctly over the enemy battlers without proper
 *      settings.
 *
 *      Example: the 'Sleep' animated state overlay should be displayed
 *               above the battler's head, while the 'Blind' overlay should
 *               cover the battler's eyes. The 'Paralysis' state, on the
 *               other hand, should encompass the whole battler's sprite.
 *
 *
 *      To achieve specific settings for each enemies, another Enemy Notetag
 *      is provided:
 *
 *          ENEMY NOTETAG:
 *                        <STATE OVERLAY DATA>
 *                            overlay INDEX: x, y, scale
 *                            overlay INDEX: x, y, scale
 *                            overlay INDEX: x, y, scale
 *                        </STATE OVERLAY DATA>
 *
 *              INDEX: the overlay index, starting at 1 for 'Poison'.
 *                  x: the horizontal offset of the overlay.
 *                  y: the vertical offset of the overlay.
 *              scale: the scaling of the overlay.
 *
 *
 *           EXAMPLE:     <STATE OVERLAY DATA>
 *                            overlay 2: 0, -48, 1
 *                            overlay 7: 12, -36, 0.8
 *                            overlay 8: -24, 0, 1.5
 *                        </STATE OVERLAY DATA>
 *
 *           An enemy battler having the above notetag will have specific
 *           state animated overlay settings for the 'Blind' (overlay 2),
 *           the 'Sleep' (overlay 7) and the 'Paralysis' (overlay 8) states.
 *           Note that the 'Blind' overlay is slightly downscaled so it just
 *           cover the enemy eyes; while the 'Paralysis' overlay is enlarged
 *           so it cover the whole enemy sprite.
 *
 *

Sprite_Enemy.prototype.setMotionFrame = function(motion, rate) {
    let frame = motion.frame;
    const maxIndex = motion.maxFrame - 1;
    if (frame === maxIndex && !motion.loop) return frame;
    if (this._animationCount % rate === 0) {
        if (!this._goesLeft) {
            if (frame < maxIndex) { 
                frame++;
            } else {
                frame--;
                this._goesLeft = true;
            }       
        } else {
            if (frame > 0) { 
                frame--;
            } else {
                frame++;
                this._goesLeft = false;
            } 
        }
    }
    motion.frame = frame; 
};

Sprite_Enemy.prototype.setMotionFrame = function(motion, rate) {
    let frame = motion.frame;
    const maxIndex = motion.maxFrame - 1;
    if (frame === maxIndex && !motion.loop) return frame;
    if (this._animationCount % rate === 0) {
        if (frame < maxIndex) { 
            frame++;
        } else {
            frame = 0;
        }       
    }
    motion.frame = frame; 
};

Sprite_Enemy.prototype.startBossCollapse = function() {
    if (this.bitmap.height && this._motionLenght) {
        this._effectDuration = this._enemy._animated ?
                Math.round(this.bitmap.height / this._motionLenght) : this.bitmap.height;
    } else {
        this._effectDuration = 0;
    }
    this._appeared = false;
};