2D_Engine_C/assets/asset_builder/README.md

Asset builder description

This program builds assets into an output file. The supported file formats are :

• image (.png)
• maps (.map which is in reality json)

The different files format are deduced from the extensions only.

The code has some optimisation problems but here is the main idea :

First calculate header wich consists of :

Description	Length
Assets number	unsigned int (32 bits)
...
Asset name	const char [] (variable length, ends with '\00')
Asset start index	unsigned int (32 bits)
...

This calculation needs to analse the content of inputs files to calculate the start offsets in the file.

Then write the content of each file in the same order as they were analysed for header calculations.

For the moment each input file is openend and analized 2 times.

Image (.png)

Convert png's RGBA8888 to custom RGB565 with #0001 in RGB565 as the transparent color. If png's alpha is null then the color of the pixel will be replaced with this.

Image asset data structure

Description	Length
Image width	unsigned int (32 bits)
Image height	unsigned int (32 bits)
Image data	depend on image size, pixel short (16 bits)

Maps (.map)

Convert from json to custom format.

Maps asset data structure

Description	Length
Map width	unsigned short (16 bits)
Map height	unsigned short (16 bits)
Map background layers nb	unsigned char (8 bits)
Map background layers data	depends map size and layer count, tile short (16 bits)
Map foreground layer data	depend on map size, tile short (16 bits)
Tileset asset name	const char [] (variable length, ends with '\00')
Map hitboxes data	depend on map size, tile unsigned char (8 bits)
Entities number	unsigned short (16 bits)
...
Entity ID	unsigned int (32 bits)
Entity components number	unsigned short (16 bits)
...
Component type	unsigned int (32 bits)
...
Component attributes	depend on attribute type
int	unsigned int (32 bits)
float	float (32 bits)
bool	_Bool (8 bits)
str	const char [] (variable length, ends with '\00')
...
...