modify()

Returns a new shader, based on the original, but with custom snippets of shader code replacing default behaviour.

Each shader may let you override bits of its behavior. Each bit is called a hook. A hook is either for the vertex shader, if it affects the position of vertices, or in the fragment shader, if it affects the pixel color. You can inspect the different hooks available by calling yourShader.inspectHooks(). You can also read the reference for the default material, normal material, color, line, and point shaders to see what hooks they have available.

modify() takes one parameter, hooks, an object with the hooks you want to override. Each key of the hooks object is the name of a hook, and the value is a string with the GLSL code for your hook.

If you supply functions that aren't existing hooks, they will get added at the start of the shader as helper functions so that you can use them in your hooks.

To add new uniforms to your shader, you can pass in a uniforms object containing the type and name of the uniform as the key, and a default value or function returning a default value as its value. These will be automatically set when the shader is set with shader(yourShader).

You can also add a declarations key, where the value is a GLSL string declaring custom uniform variables, globals, and functions shared between hooks. To add declarations just in a vertex or fragment shader, add vertexDeclarations and fragmentDeclarations keys.