Class FunctionChain

vispy/visuals/shaders/function.py:569–749

Subclass that generates GLSL code to call Function list in order Functions may be called independently, or composed such that the output of each function provides the input to the next. Parameters ---------- name : str The name of the generated function funcs : list

class FunctionChain(Function):
    """Subclass that generates GLSL code to call Function list in order

    Functions may be called independently, or composed such that the
    output of each function provides the input to the next.

    Parameters
    ----------
    name : str
        The name of the generated function
    funcs : list of Functions
        The list of Functions that will be called by the generated GLSL code.

    Examples
    --------
    This creates a function chain::

        >>> func1 = Function('void my_func_1() {}')
        >>> func2 = Function('void my_func_2() {}')
        >>> chain = FunctionChain('my_func_chain', [func1, func2])

    If *chain* is included in a ModularProgram, it will generate the following
    output::

        void my_func_1() {}
        void my_func_2() {}

        void my_func_chain() {
            my_func_1();
            my_func_2();
        }

    The return type of the generated function is the same as the return type
    of the last function in the chain. Likewise, the arguments for the
    generated function are the same as the first function in the chain.

    If the return type is not 'void', then the return value of each function
    will be used to supply the first input argument of the next function in
    the chain. For example::

        vec3 my_func_1(vec3 input) {return input + vec3(1, 0, 0);}
        void my_func_2(vec3 input) {return input + vec3(0, 1, 0);}

        vec3 my_func_chain(vec3 input) {
            return my_func_2(my_func_1(input));
        }
    """

    def __init__(self, name=None, funcs=()):
        # bypass Function.__init__ completely.
        ShaderObject.__init__(self)
        if not (name is None or isinstance(name, str)):
            raise TypeError("Name argument must be string or None.")
        self._funcs = []
        self._code = None
        self._name = name or "chain"
        self._args = []
        self._rtype = 'void'