Shader Library - Procedural GPU Patterns

Catlike Coding Godot details a small but useful shader-library pattern for Godot: use conditional compilation to make an include file behave differently when it is compiled on its own versus when it is pulled into another shader. The immediate problem is a duplicate PatternSample definition, which is solved by guarding the shared code with a macro such as PATTERN_SAMPLE and checking it with #ifndef / #endif.

The tutorial walks through a deliberate #error test first, then shows the fix: define PATTERN_SAMPLE before including fractal_pattern.gdshaderinc, and let the include file skip its own type declaration when that macro is present. That keeps the include reusable while avoiding invalid duplicate definitions during compilation.

For developers building shader libraries, the takeaway is less about the specific fractal code and more about maintainable composition. Conditional compilation can keep shared GPU code modular, but the post also cautions that macros should stay simple; once they start generating complex code, debugging becomes much harder.

The example then trims PatternSample down to a minimal struct with a single float value and adds compatible helper functions like zero_pattern_sample, add, and multiply. It’s a straightforward pattern, but one that scales well for teams trying to build a library of reusable shader snippets without turning every include into a one-off special case.