• Where to find it:

• NodeGraph / Right Mouse Click / Add Nodes / Math / Extension Pack / F /

 fwidth (uv) returns the sum of the absolute derivatives in x and, transformed into UV Space.

Other than the fwidth (screenspace) node which uses the classic opengl fwidth function call, this node transforms the derivatives into UV Space

vec4 Gate = vec4(float($R),float($G),float($B),float($A));

vec2 uv = State.UV;

vec2 uxvx = dFdx(uv);

vec2 uyvy = dFdy(uv);

mat2 T = mat2(uxvx.s,uyvy.s,uxvx.t,uyvy.t);

T = (determinant(T) == 0) ? mat2(0) : inverse(T);

vec4 input = #F*Gate;

vec4 dfdx = dFdx(input);

vec4 dfdy = dFdy(input);

vec2 tdfdx = T*vec2(dfdx.x,dfdy.x);

vec2 tdfdy = T*vec2(dfdx.y,dfdy.y);

vec2 tdfdz = T*vec2(dfdx.z,dfdy.z);

vec2 tdfdw = T*vec2(dfdx.w,dfdy.w);

UDeriv = vec4(tdfdx.x, tdfdy.x, tdfdz.x, tdfdw.x);

VDeriv = vec4(tdfdx.y, tdfdy.y, tdfdz.y, tdfdw.y);

UDeriv.a = $A ? UDeriv.a : 1.0;

VDeriv.a = $A ? VDeriv.a : 1.0;

FWidth = abs(UDeriv) + abs(VDeriv);

https://registry.khronos.org/OpenGL-Refpages/gl4/html/fwidth.xhtml

• F

Specifies the expression of which to take the partial derivative.

• FWidth

Return the sum of the absolute value of derivatives in x and y, transformed into UV Space

• U Derivative

Return x derivative transformed into UV Space

• V Derivative

Return y derivative transformed into UV Space