Template:NW4FCurve
Curve
Curves store how animations are performed over time and store the required keys and values for this. They appear in multiple animation subfiles, and their header is of 0x24 bytes size (for BFRES versions earlier than 3.4.0.0, they are of 0x20 bytes size).
Offset | Size | Type | Description | ||||||||||||||||||||||||||||||||||||||||||||||||
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0x00 | 2 | UInt16 | Flags. Sets of bits packed as xxxxxxxx xCCCKKFF.
| ||||||||||||||||||||||||||||||||||||||||||||||||
0x02 | 2 | UInt16 | Key count. | ||||||||||||||||||||||||||||||||||||||||||||||||
0x04 | 4 | UInt32 | Target Offset, an offset in bytes into the corresponding Animation Data structure to animate the field at that relative address. | ||||||||||||||||||||||||||||||||||||||||||||||||
0x08 | 4 | Single | Start frame, the first frame at which a key is placed. | ||||||||||||||||||||||||||||||||||||||||||||||||
0x0C | 4 | Single | End frame, the last frame at which a key is placed. | ||||||||||||||||||||||||||||||||||||||||||||||||
0x10 | 4 | Int32 / Single | Data scale, multiplier to the raw key values to get the final result. Together with Data offset, it is chosen carefully to consider an optimal granularity between the stored values. | ||||||||||||||||||||||||||||||||||||||||||||||||
0x14 | 4 | Single | Data offset, added to the raw values (after multiplying them with Data scale) to get the final key value. | ||||||||||||||||||||||||||||||||||||||||||||||||
if BFRES version >= 3.4.0.0 | |||||||||||||||||||||||||||||||||||||||||||||||||||
0x18 | 4 | Single | Data delta, stores the difference between the first and last key value. | ||||||||||||||||||||||||||||||||||||||||||||||||
0x1C | 4 | Int32 | Frame array offset. | ||||||||||||||||||||||||||||||||||||||||||||||||
0x20 | 4 | Int32 | Key array offset. | ||||||||||||||||||||||||||||||||||||||||||||||||
0x24 | End of Curve | ||||||||||||||||||||||||||||||||||||||||||||||||||
else | |||||||||||||||||||||||||||||||||||||||||||||||||||
0x18 | 4 | Int32 | Frame array offset. | ||||||||||||||||||||||||||||||||||||||||||||||||
0x1C | 4 | Int32 | Key array offset. | ||||||||||||||||||||||||||||||||||||||||||||||||
0x20 | End of Curve |
Frames
The Curve header points to a Frame array which stores values controlling at which frame a Key from the Key array is placed. Thus, the array has as many elements as specified in Key count. The data type of the frames is given in the Curve's Flags.
The end of the array is aligned to 4 bytes.
Keys
The Curve header points to a Key array which stores the key values and additional values to interpolate the curve from one point to the next. Thus, the array has as many elements as specified in Key count, multiplied by the number of elements stored per key (depending upon the CCC Curve Type bits in the Curve Flags as described above). The data type of each element is given by the KK Key Type bits in the Curve Flags.
The end of the array is aligned to 4 bytes.
Step Curves
The elements apparently represent the key values directly.
Linear Curves
For linearly interpolated curves, 2 elements are stored per key:
- Value at which the key is set. To get the final value, scale and then offset it.
- Delta to value at next frame to which the curve linearly runs. To get the final value, scale it. If there is no next frame, this is always 0.
A key can be discarded by the next key if that one is stored at the same frame. In that case, only the value of the next key is stored, and the delta of the previous key is adjusted to run to the value of the now discarded key.
This example curve's keys are stored as SByte elements. The curve scale was computed as 2, the offset as 200 and the curve delta (if available in the BFRES version) as 300. Due to the lower key in frame 20 being discarded in favor of the higher key, only 3 keys are stored in 6 elements as follows.
Point | Array Index | Raw Value | *2 (Scale) | +200 (Offset) | Notes |
---|---|---|---|---|---|
0,0 | 0 | -100 | -200 | 0 | Initial key with value 0. |
(20,254) | 1 | 127 | 254 | - | Delta to end value of initial key at next frame. |
20,254 | - | - | - | - | This key is discarded in favor of the next. |
20,400 | 2 | 100 | 200 | 400 | Overrides previous key. |
(30,300) | 3 | -50 | -100 | - | End value of overriding key at next frame. |
30,300 | 4 | 50 | 100 | 300 | Value of fourth (but third stored) key. |
(end) | 5 | 0 | 0 | - | Since no frame follows, always 0. |
Hermite Curves
For hermite curves, 4 elements are stored for each key. It is unclear how to exactly interprete them to form the curve out of it.