Anagram shift effect GameMaker

// anagram shift effect in GameMaker by oliver @pixelchipcode
// Create Event
// First set up our variables
anagrams = [
    "astronomers",
    "no more stars"
];

current_anagram = 0;
next_anagram = 1;
transition_time = 1.5;
transition_progress = 0;
is_transitioning = false;
letters = ds_list_create();

// Initialize starting positions
function init_letters() {
    ds_list_clear(letters);
    var spacing = 20;
    var current_word = anagrams[current_anagram];

    for (var i = 0; i < string_length(current_word); i++) {
        var letter = {
            char: string_char_at(current_word, i + 1),
            current_x: x + (i * spacing),
            target_x: x + (i * spacing),
            start_x: x + (i * spacing),
            alpha: 1,
            start_alpha: 1,
            target_alpha: 1
        };
        ds_list_add(letters, letter);
    }
}

// Function to find best target position for each letter
function assign_target_positions() {
    var next_word = anagrams[next_anagram];
    var spacing = 20;
    var used_indices = array_create(string_length(next_word), false);

    // Update start positions for all existing letters
    for (var i = 0; i < ds_list_size(letters); i++) {
        var letter = letters[|i];
        letter.start_x = letter.current_x;
        letter.start_alpha = letter.alpha;
    }

    // First pass: match exact characters
    for (var i = 0; i < ds_list_size(letters); i++) {
        var letter = letters[|i];
        var found = false;

        for (var j = 0; j < string_length(next_word); j++) {
            if (!used_indices[j] && string_char_at(next_word, j + 1) == letter.char) {
                letter.target_x = x + (j * spacing);
                letter.target_alpha = 1;
                used_indices[j] = true;
                found = true;
                break;
            }
        }

        // If no match found, letter will fade out
        if (!found) {
            letter.target_alpha = 0;
        }
    }

    // Create new letters for unmatched characters in target word
    for (var i = 0; i < string_length(next_word); i++) {
        if (!used_indices[i]) {
            var new_letter = {
                char: string_char_at(next_word, i + 1),
                current_x: x + (i * spacing) + (random_range(-50, 50)),
                start_x: x + (i * spacing) + (random_range(-50, 50)),
                target_x: x + (i * spacing),
                alpha: 0,
                start_alpha: 0,
                target_alpha: 1
            };
            ds_list_add(letters, new_letter);
        }
    }
}


// New easing function (can be placed in Create event with other functions)
function EaseInOutCubic(time, start, dest, duration) {
    var change = dest - start;  // Calculate the total change in value
    time /= duration * 0.5;

    if (time < 1) {
        return change * 0.5 * power(time, 3) + start;
    }

    return change * 0.5 * (power(time - 2, 3) + 2) + start;
}
// Initialize the first word
init_letters();

// Step Event
if (mouse_check_button_pressed(mb_left)) {
    is_transitioning = true;
    transition_progress = 0;
    assign_target_positions();  // Calculate targets based on current next_anagram
    current_anagram = next_anagram;  // Then update indices after
    next_anagram = (next_anagram + 1) % array_length(anagrams);
}

if (is_transitioning) {
    transition_progress += delta_time / 1000000 / transition_time;

    // Update all letter positions and alphas
    for (var i = 0; i < ds_list_size(letters); i++) {
        var letter = letters[|i];
        // Use new easing function for both position and alpha
        letter.current_x = EaseInOutCubic(transition_progress, letter.start_x, letter.target_x, 1);
        letter.alpha = EaseInOutCubic(transition_progress, letter.start_alpha, letter.target_alpha, 1);
    }

    if (transition_progress >= 1) {
        is_transitioning = false;

        // Clean up any fully faded out letters
        var i = 0;
        while (i < ds_list_size(letters)) {
            if (letters[|i].alpha <= 0) {
                ds_list_delete(letters, i);
            } else {
                i++;
            }
        }
    }
}

// Draw Event
draw_set_color(c_white);
draw_set_font(Font2)
for (var i = 0; i < ds_list_size(letters); i++) {
    var letter = letters[|i];
    draw_set_alpha(letter.alpha);
    draw_text(letter.current_x, y, letter.char);
}
draw_set_alpha(1);