Animate Blender 3d piano

piano_blender.py

import bpy
import pretty_midi
from collections import defaultdict

# Parameters
BUFFER = 12
fps = 24
midi_file_path = 'wii-music.mid'
keys_collection = bpy.data.collections['Keys']
key_press_action = bpy.data.actions['Key Press']

def get_note_start_times_in_frames(midi_file_path, fps):
    midi_data = pretty_midi.PrettyMIDI(midi_file_path)
    if len(midi_data.instruments) > 1:
        raise Exception("MIDI file contains more than one track.")
    notes_frames = defaultdict(list)
    for note in midi_data.instruments[0].notes:
        start_frame = int(note.start * fps)
        end_frame = int(note.end * fps)
        notes_frames[note.pitch].append((start_frame + BUFFER, end_frame + BUFFER))
    return notes_frames


def get_delta_transforms(action, frame):
    delta_loc = [0.0, 0.0, 0.0]
    delta_rot = [0.0, 0.0, 0.0]
    for fcurve in action.fcurves:
        for keyframe_point in fcurve.keyframe_points:
            if keyframe_point.co.x == frame:
                if fcurve.data_path == 'delta_location':
                    delta_loc[fcurve.array_index] = keyframe_point.co.y
                elif fcurve.data_path == 'delta_rotation_euler':
                    delta_rot[fcurve.array_index] = keyframe_point.co.y
    return delta_loc, delta_rot


def set_keyframe(obj, frame, delta_loc, delta_rot):
    # Reset delta transformations before applying new ones
    obj.delta_location = (0, 0, 0)
    obj.delta_rotation_euler = (0, 0, 0)

    # Apply new delta transformations
    obj.delta_location = delta_loc
    obj.delta_rotation_euler = delta_rot

    # Insert keyframes for all axes
    for i in range(3):  # XYZ
        obj.keyframe_insert(data_path="delta_location", index=i, frame=frame)
        obj.keyframe_insert(data_path="delta_rotation_euler", index=i, frame=frame)


def animate_piano_keys(note_frames, keys_collection, KEY_UP_POSITION, KEY_DOWN_POSITION):
    # For every Key
    for key_object in keys_collection.objects:

        # For the notes played on this Key
        key_notes = note_frames.get(int(key_object.name), [])

        # I forget what this means
        prev_up_frame = 0

        anim_length = 3

        for down_frame, up_frame in key_notes:
            
            # Push Key Down
            # Before can push key down, it needs to be UP
            PREV_UP = max(down_frame - anim_length, prev_up_frame)
            set_keyframe(key_object, PREV_UP, *KEY_UP_POSITION)  # UP
            set_keyframe(key_object, down_frame, *KEY_DOWN_POSITION)  # DOWN
            
            set_keyframe(key_object, up_frame-anim_length, *KEY_DOWN_POSITION)  # STAY DOWN
            set_keyframe(key_object, up_frame, *KEY_UP_POSITION)  # UP 
            prev_up_frame = up_frame


# Get delta transformations from the first and last keyframes of the actions
KEY_UP_POSITION = get_delta_transforms(key_press_action, key_press_action.frame_range[0])
KEY_DOWN_POSITION = get_delta_transforms(key_press_action, key_press_action.frame_range[1])

print(f'KEY_UP_POSITION -- {KEY_UP_POSITION}')
print(f'KEY_DOWN_POSITION -- {KEY_DOWN_POSITION}')

# Iterate through all objects in the scene
for obj in bpy.data.objects:
    # Check if the object has animation data
    if obj.animation_data:
        # Clear the animation data
        obj.animation_data_clear()

# Get note frames and animate keys
note_frames = get_note_start_times_in_frames(midi_file_path, fps)
animate_piano_keys(note_frames, keys_collection, KEY_UP_POSITION, KEY_DOWN_POSITION)

# Iterate through all objects in the scene
for obj in bpy.data.objects:
    # Check if the object has animation data and NLA tracks
    if obj.animation_data and obj.animation_data.nla_tracks:
        for track in obj.animation_data.nla_tracks:
            for strip in track.strips:
                strip.extrapolation = 'NOTHING'

print("Extrapolation mode set to 'Nothing' for all NLA strips.")