blender-archive/source/blender/draw/modes/shaders/overlay_face_wireframe_frag.glsl

#ifndef SELECT_EDGES
uniform vec3 wireColor;
uniform vec3 rimColor;

flat in vec3 ssVec0;
flat in vec3 ssVec1;
flat in vec3 ssVec2;
in float facing;

#  ifdef LIGHT_EDGES
flat in vec3 edgeSharpness;
#  endif

out vec4 fragColor;
#endif

float min_v3(vec3 v) { return min(v.x, min(v.y, v.z)); }
float max_v3(vec3 v) { return max(v.x, max(v.y, v.z)); }

/* In pixels */
const float wire_size = 0.0; /* Expands the core of the wire (part that is 100% wire color) */
const float wire_smooth = 1.2; /* Smoothing distance after the 100% core. */

/* Alpha constants could be exposed in the future. */
const float front_alpha = 0.35;
const float rim_alpha = 0.75;

void main()
{
#ifndef SELECT_EDGES
	vec3 ss_pos = vec3(gl_FragCoord.xy, 1.0);
	vec3 dist_to_edge = vec3(
		dot(ss_pos, ssVec0),
		dot(ss_pos, ssVec1),
		dot(ss_pos, ssVec2)
	);

#  ifdef LIGHT_EDGES
	vec3 fac = abs(dist_to_edge);
#  else
	float fac = min_v3(abs(dist_to_edge));
#  endif

	fac = smoothstep(wire_size + wire_smooth, wire_size, fac);

	float facing_clamped = clamp((gl_FrontFacing) ? facing : -facing, 0.0, 1.0);

	vec3 final_front_col = mix(rimColor, wireColor, 0.05);
	fragColor = mix(vec4(rimColor, rim_alpha), vec4(final_front_col, front_alpha), facing_clamped);

#  ifdef LIGHT_EDGES
	fragColor.a *= max_v3(fac * edgeSharpness);
#  else
	fragColor.a *= fac;
#  endif
#endif
}