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ShaderTool

This tool parses GLSL shader files (mainly *.vert, *.frag, *.geom and *.comp) and generates C++ source files for them.

You automatically get the shaders added back to the code after saving a shader file and trigger a re-build.

The cmake macros expect the shader source below the module in a shaders/ directory.

set(SHADERS first second)
engine_generate_shaders(mymodulename ${SHADERS})

The shaders given in this example would be located at src/modules/mymodulename/shaders/first.*. The tool automatically detects the type of programs that should be connected in the final shader.

The code is generated into the build directory in generated/shaders.

Description

The generator uses ShaderTemplate.h.in and UniformBufferTemplate.h.in as a base to generate the C++ source files.

There are several variables in the template file that are replaced by the generator.

  • $includes$
  • $namespace$

  • $name$

  • $setters$

  • $attributes$
  • $uniforms$

  • $uniformarrayinfo$

  • $shutdown$

  • $uniformbuffers$

The parser includes a preprocessor.

You can export constants from the GLSL shader code to the generated C++ code by using $constant.

Use $constant varname 42 to generate a method that returns 42 with a name getVarname

Branching / Feature toggles

Usually you don't have to use branching and uniforms for feature toggles. You can use cvars with the flag CV_SHADER set. If you are going to change one of these cvars, the shaders are recompiled with the value of the cvar given as preprocessor define.

This means that you can do stuff like:

#if cl_shadowmap == 1
   [...]
#else
   [...]
#endif

The #define of cl_shadowmap is done by the shader system at compile time.