Animated flora

/// CREATE
image_speed      = 0
image_index      = floor(random(sprite_get_number(sprite_index)))
// image_blend      = make_colour_rgb(98, 123, 61)
#region Wind effects
SWAY_INTENSITY = random_range(0.04, 0.07)
SWAY_DURATION  = random_range(1.4, 1.7  ) * room_speed
SWAY_DELTA     = 180 / SWAY_DURATION
SWAY           = true
SWAY_OFFSET    = sprite_get_width(sprite_index) * SWAY_INTENSITY
STEP           = 0

ULX  = x - sprite_get_xoffset(sprite_index)
ULY  = y - sprite_get_yoffset(sprite_index)
URX  = x + sprite_get_width  (sprite_index) - sprite_get_xoffset(sprite_index)
URY  = ULY
LRX  = URX
LRY  = y + sprite_get_height (sprite_index) - sprite_get_yoffset(sprite_index)
LLX  = ULX
LLY  = LRY
TOPY = URY
#endregion

/// STEP
/// @description Wind effects
if SWAY {
    STEP ++
    var deg = STEP * SWAY_DELTA;
    ULY = TOPY - sin(degtorad(deg)) * SWAY_INTENSITY * sprite_get_height(sprite_index)
    URY = TOPY + sin(degtorad(deg)) * SWAY_INTENSITY * sprite_get_height(sprite_index)
    ULX = LLX  + sin(degtorad(deg)) * SWAY_OFFSET
    URX = LRX  + sin(degtorad(deg)) * SWAY_OFFSET

    if STEP > SWAY_DURATION {
//     SWAY = false
       ULY  = lerp(ULY, TOPY, 0.15)
       URY  = lerp(URY, ULY , 0.15)
       ULX  = lerp(ULX, LLX , 0.15)
       URX  = lerp(URX, LRX , 0.15)
    }
}

/// DRAW / script: draw_flora()
draw_sprite_pos(sprite_index, image_index, ULX, ULY, URX, URY, LRX, LRY, LLX, LLY, image_alpha)

/// script: wind_collision()
/// @desc This is called any time you want the grass to move. I use a collision with a wind object that passes over the entire room,
///       but you could just as easily put this script in a timer or alarm as well.

/// @func wind_collision(intensity)
/// @arg0 int intensity (between 0 and 10)
if not SWAY {
    var SWAY_DEGREE = 0;
    STEP = 0
    SWAY = true
    SWAY_INTENSITY = random_range(0.01, 0.02)
    SWAY_OFFSET    = sprite_get_width(sprite_index) * SWAY_INTENSITY
    SWAY_DURATION  = random_range(1.4, 1.7) * room_speed
    SWAY_DEGREE    = wave(argument0, -0.5, SWAY_DURATION, SWAY_OFFSET)
    SWAY_DELTA     = 180 / SWAY_DURATION * SWAY_DEGREE
}