ABNK ("KNBA") - Animation Bank

Author(s): Gonhex
Research: NOCASH, magical, Gonhex

The animation bank is used to animate 2D graphics. It requires an object to work on, which can be either a cell bank or a multi cell bank. Internally it works like frame by frame animations. To achieve more dynamic results, affine transformations can be applied to selected frames.

ABNK ("KNBA") - Animation Bank

Data Structure

Section Container

struct ContainerSectionABNK
{
    /* 0x0    */ struct NitroSectionHeader sectionHeader;
    /* 0x8    */ struct ContainerABNK sectionData;
}; // entry size = sectionHeader.lengthSection

Field Name	Description	Data Type
sectionHeader	Header of this section. `sectionHeader.signature = "KNBA"`.	NitroSectionHeader
sectionData	Content of this section.	ContainerABNK

ABNK Container

struct ContainerABNK
{
    // header
    /* 0x00 */ uint16_t numberSequences;
    /* 0x02 */ uint16_t numberFrames;
    /* 0x04 */ uint32_t offsetDataSequences;
    /* 0x08 */ uint32_t offsetDataFrame
    /* 0x0C */ uint32_t offsetDataFrameProperties;
    /* 0x10 */ uint32_t unknown0;
    /* 0x14 */ uint32_t unknown1;
    
    // data
    /* offsetDataSequences       */ struct Sequence dataSequences[numberSequences];
    /* offsetDataFrame           */ struct Frame dataFrames[numberFrames];
    /* offsetDataFrameProperties */ struct FrameProperties dataFrameProperties[?];
}; // entry size = sectionHeader.lengthSection - 0x8

Field Name	Description	Data Type
numberSequences	Number of sequences.	uint16_t
numberFrames	Number of frames.	uint16_t
offsetDataSequences	Offset to the sequence data section relative to `ContainerABNK`.	uint32_t
offsetDataFrame	Offset to the frame data section relative to `ContainerABNK`.	uint32_t
offsetDataFrameProperties	Offset to the frame property data section relative to `ContainerABNK`.	uint32_t
unknown0	Unused offset?	uint32_t
unknown1	Unused offset?	uint32_t
dataSequences	Animated object data.	Sequence[]
dataFrames	Frame configuration data. Duration in frames and an index to the properties.	Frame[]
dataFrameProperties	Current (multi) cell index and affine transformation data, depends on the sequence.	FrameProperties[]

Sequence

struct Sequence
{
    /* 0x0 */ uint32_t numberFrames;
    /* 0x4 */ uint16_t animationType;
    /* 0x6 */ uint16_t cellType;
    /* 0x8 */ uint32_t loopMode;
    /* 0xC */ uint32_t offsetFrame;
}; // entry size = 0x10

Field Name	Description	Data Type
numberFrames	Refers to the count of frame-blocks used in this sequence.	uint32_t
animationType	`0x0` = sequence, `0x1` = affine transform, `0x2` = translation.	uint16_t
cellType	`0x1` = unique cell, `0x2` = multi cell.	uint16_t
loopMode	Behaviour of the frame sequence, values are documented in Loop Mode.	uint32_t
offsetFrame	Offset to the first used frame, relative to `offsetDataFrame`.	uint32_t

Frame

struct Frame
{
    /* 0x0 */ uint32_t offsetProperties;
    /* 0x4 */ uint16_t durationInFrames;
    /* 0x6 */ int16_t unknown0;
}; // entry size = 0x8

Field Name	Description	Data Type
offsetProperties	Offset to the first used frame property, relative to `offsetDataFrameProperties`.	uint32_t
durationInFrames	Number of frames remaining in this state, 60 frames per second.	uint16_t
unknown0	Always `0xBEEF`.	int16_t

Frame Properties

// if animationType == 0
struct FrameProperties
{
    /* 0x0 */ uint16_t cellIndex;
}; // entry size = 0x2

// if animationType == 1
struct FrameProperties
{
    /* 0x0 */ uint16_t cellIndex;
    /* 0x2 */ uint16_t rotate;
    /* 0x4 */ fx<1.19.12> scaleW;
    /* 0x8 */ fx<1.19.12> scaleH;
    /* 0xC */ int16_t translateX;
    /* 0xE */ int16_t translateY;
}; // entry size = 0x10

// if animationType == 2
struct FrameProperties
{
    /* 0x0 */ uint16_t cellIndex;
    /* 0x2 */ uint16_t unknown0;
    /* 0x4 */ int16_t translateX;
    /* 0x6 */ int16_t translateY;
}; // entry size = 0x8

Field Name	Description	Data Type
cellIndex	Index of the displayed cell or multi cell block.	uint16_t
rotate	Rotation angle, using the full range of uint16_t for one turn.	uint16_t
unknown0	Unused, `0x0` or `0xBEEF`.	uint16_t
scaleW	Width scaling factor.	fx<1.19.12>
scaleH	Height scaling factor.	fx<1.19.12>
translateX	X position adjustment.	int16_t
translateY	Y position adjustment.	int16_t

Important: The structs for animationType > 0 must be DWORD aligned. If there is a region with an odd number of type-0 properties, a dummy entry is appended as padding.

Specification

Animation

To animate a sprite, three data blocks are required.

The entry point is the sequence data. This defines the gereral properties of a sequence. How many different frames are involved? Are transformations applied or does the animation only rely on changing images? This decision is applyed to all frames, which are part of the sequence.
The frame data tells, how long the image remains in this state. On a 60 fps system, setting it to 60 frames (0x3C) makes it last one second before switching to the next frame. It also points to an offset in the frame property data. To save memory, multiple frames can point to the same property offset.
The structure of the frame properties depends on the animationType setting from the sequence data. If it is == 0, all it does is displaying the selected cell. If it is == 2, the position can also be changed. animationType == 1 also adds scaling and rotation.

If the animation is applied to a normal cell bank, the image in each frame is static, meaning if one frame is set to remain for one second and the transformation is rotate 180°, the image will be displayed upside down for one second. If the animation is applied to multi cells, which already have animated parts, it will loop through the animations of the multi cell, while "being upside down".

Loop Mode

The loop mode defines what to do, after the animation reached its last frame. There are four values, which can be used:

Stop animation at last frame.
Repeat animation after last frame.
Play frames backwards after reaching the last frame and stop at first frame.
Ping pong mode, repeat alternately forward and backward.

Other values are not supported and end up in the behavior of 1.

Files

TODO

Link fixed point definition

ABNK ("KNBA") - Animation Bank

Table of Contents​

Data Structure​

Section Container​

ABNK Container​

Sequence​

Frame​

Frame Properties​

Specification​

Animation​

Loop Mode​

Files​

TODO​

Table of Contents