//pref
Ambient|float|0.0|0.5|1
Diffuse|float|0.0|0.7|1
Specular|float|0.0|0.2|1
Shininess|float|1|60|120
WireWidth|float|0.1|1|24
WireType|int|0|0|2
LightBackfaces|bool|false
Wireframe useful for evaluating mesh quality. Copyright 2015 Chris Rorden, BSD2clause.|note
//vert
#version 330
layout(location = 0) in vec3 Vert;
layout(location = 3) in vec3 Norm;
layout(location = 6) in vec4 Clr;
out vec3 vN, vL, vV;
out vec4 vPmvp, vClr, vP;
uniform mat4 ModelViewProjectionMatrix;
uniform mat4 ModelViewMatrix;
uniform mat3 NormalMatrix;
uniform vec3 LightPos = vec3(0.0, 20.0, 30.0); //LR, -DU+, -FN+
void main() {
    vN = normalize((NormalMatrix * Norm));
    vP = vec4(Vert, 1.0);
    gl_Position = ModelViewProjectionMatrix * vec4(Vert, 1.0);
    vPmvp = gl_Position;
    vL = normalize(LightPos);
    vV = -vec3(ModelViewMatrix*vec4(Vert,1.0));
    vClr = Clr;
}
//geom
#version 330
in vec3 vL[3], vN[3], vV[3];
in vec4 vP[3], vPmvp[3], vClr[3];
layout (triangles) in;
layout (triangle_strip, max_vertices = 3) out;
out vec3 gE, gL, gN, gV;
out vec4 gP, gClr;

void main(void) {
    for(int i=0; i < 3; i++) {
    	gl_Position = vPmvp[i];
    	if (i == 0)
    		gE = vec3(1.0, 0.0, 0.0);
    	else if (i == 1)
    		gE = vec3(0.0, 1.0, 0.0);
    	else
    		gE = vec3(0.0, 0.0, 1.0);
    	gL = vL[i];
    	gN = vN[i];
    	gV = vV[i];
    	gP = vP[i];
    	gClr = vClr[i];
        EmitVertex();
    }
    EndPrimitive();
}
//frag
#version 330
uniform float Ambient, Diffuse, Specular, Shininess, WireWidth;
uniform int WireType;
uniform bool LightBackfaces;
uniform vec4 ClipPlane;
in vec3 gE, gL, gN, gV;
in vec4 gP, gClr;
out vec4 color;

float edgeFactor(){
    vec3 d = fwidth(gE);
    vec3 a3 = smoothstep(vec3(0.0), d*WireWidth, gE);
    return min(min(a3.x, a3.y), a3.z);
}

vec3 desaturate(vec3 color, float amount) {
    vec3 gray = vec3(dot(vec3(0.2126,0.7152,0.0722), color));
    return vec3(mix(color, gray, amount));
}

void main() {
	if ((ClipPlane[0] < 1.5) && (dot( ClipPlane, gP) > 0.0)) discard;
	vec3 l = normalize(gL);
	vec3 n = normalize(gN);
	vec3 h = normalize(l+normalize(gV));
	vec3 a = gClr.rgb;
	vec3 d = a * Diffuse;
	a *= Ambient;
	float backface = 1.0 - step(0.0, n.z); //1=backface
	vec3 backcolor = desaturate(0.5 * a + 0.5 * d *  abs(dot(n,l)), 0.5);
	n = mix(n, -n, backface * float(LightBackfaces)); //reverse normal if backface AND two-sided lighting
	d *= max(dot( l, n), 0.0);
	float s = pow(max(0.0,dot(n,h)), Shininess) * Specular;
	vec4 face = vec4(a + d + s, 1.0 - edgeFactor());
	if (face.a < 0.5) discard;
	backface = 1.0 - step(0.0, n.z); //1=backface
	face.rgb = mix(face.rgb, backcolor.rgb, backface);
	if (WireType == 1)
		face.rgb = vec3(0.0, 0.0, 0.0);
	if (WireType == 2)
		face.rgb = vec3(1.0, 1.0, 1.0);
	color = face;
}
// Solid Wireframe, NVIDIA Whitepaper WP-03014-001_v01
// http://codeflow.org/entries/2012/aug/02/easy-wireframe-display-with-barycentric-coordinates/
// http://www.imm.dtu.dk/~janba/Wireframe/
