Is it possible to "extend" an existing shader at runtime or not ?

Unity Engine
1

hi gods of code…

let’s say i have

  • a shader A that is the main shader
  • shaders (or code blocks) B,C that do something in addition

is it possible to add B to A ? or extend A with B (in the same pass or not)

at run time :

if thisistrue then add B to A

or in the shader A it self , something like

shader A {
bla
bla
bla

add shader B (or code block B)

if thisistrue then add shader C ( or code block C)
}

this could be interesting to extend features of a base shaders like :
add rim effect
add kinda anisotropy
add glittering
etc etc

thanks for watching

Victor

2

No really possible to directly feed concatenated shader code, as you can’t be sure the platform can compile shader at runtime. Also it would mean insert inside the function from shader A just part of some code, hoping the var & structures contains what you expect at that time etc… or do it in multipass, which is equal to one draw call per pass…

But you could achieve that with multi_compile :

Just write a shader with all those effects inside #ifdef/#endif , then use Material.EnableKeyword (or Shader.Material.EnableKeyword for globally define) to enable/disable those feature.

Pros : your shader is optimal, as it’s that specific variant precompiled that is used
Cons : increase build size, as all combination of multi_compile keywords are compiled & stocked.

1 Like
3

great help, thanks a lot guillaume.