filterstep vex function

Contexts: displace , fog , light , photon , shadow , surface

Returns the anti-aliased weight of the step function.

float filterstep(float edge, float x)
float filterstep(float edge, float x0, float x1)

Returns the anti-aliased weight of the step function. The step function returns 0 if x is less than edge and 1 if x is greater than edge. filterstep function returns a fraction representing the filtered area under the step function.

You can optionally specify a filter kernal and width using the “filter” and “width” additional arguments in the same fashion as for texture functions.

f = filterstep(0.5, s+t, "filter", "gauss", "width", 2);

The filterstep(float edge, x, ...) form is roughly equivalent to:

f = filterstep(edge, x, x + abs(Du(x) + Dv(x)));