History of Post-process shader(No. 2) - WarmeY2K - A complete, fast and fun game engine for the web

Fragment variables†

Variables	Scope	Type	Description
------------------------	-------	--------------	---------------------------------------------
FragUV	Attr	vec2	The pixel uv position
------------------------	-------	--------------	---------------------------------------------
PARAMS	Uniform	Params	Global parameters
SIZE	Uniform	vec2	The resolution screen size
SOURCE_TEXTURE	Uniform	Texture	The colored source texture (with lit)
NORMALS_TEXTURE	Uniform	Texture	The normals source texture
IDS_TEXTURE	Uniform	Texture	The indexes source texture
DEPTH_TEXTURE	Uniform	Texture	The depth source texture
SHADOW_FACTOR_TEXTURE	Uniform	Texture	The shadow-volume texture
SHADOW_DEPTH_CCW_TEXTURE	Uniform	Texture	The shadow-volume ccw depth texture
SHADOW_DEPTH_CW_TEXTURE	Uniform	Texture	The shadow-volume cw depth texture
------------------------	-------	--------------	---------------------------------------------
outputColor	var	vec4	The fragment shader output color
normal	var	vec3	The pixel normal
id	var	vec4	The pixel id
depth	var	float	The pixel depth
shadowFactor	var	vec4	The pixel shadow-volume factor
shadowDepthCW	var	float	The pixel shadow-volume cw depth
shadowDepthCCW	var	float	The pixel shadow-volume ccw depth
flags	var	int	The pixel filter flags
pixelCoord	var	vec2	The pixel coord after pixelation

You can make your own ppe shader by append code to the existing one.
See PPE_VERT_EXT and PPE_FRAG_EXT variables in vite.config.ts.