//pref
Ambient|float|0.0|0.5|1
Diffuse|float|0.0|0.7|1
Specular|float|0.0|0.2|1
GridSpacing|float|0.01|2|5
WireWidth|float|0.01|0.15|1.0
xGrid|bool|true
yGrid|bool|true
zGrid|bool|true
Blinn-Phong shading with Lambertian diffuse. 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 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);
    vL = normalize(LightPos);
    vV = -vec3(ModelViewMatrix*vec4(Vert,1.0));
    vClr = Clr;
}
//frag
#version 330
in vec4 vClr, vP;
in vec3 vN, vL, vV;
out vec4 color;
uniform float Ambient = 0.6;
uniform float Diffuse = 0.7;
uniform float Specular = 0.2;
uniform float Shininess = 60.0;
uniform float GridSpacing = 0.3;
uniform float WireWidth = 0.2;
uniform bool xGrid = true;
uniform bool yGrid = true;
uniform bool zGrid = true;
uniform vec4 ClipPlane = vec4(2.0, 0.0, 0.0, 0.0);

void main() {
	if ((ClipPlane[0] < 1.5) && (dot( ClipPlane, vP) > 0.0)) discard;
	float W = pow(GridSpacing, 4.0);
	float o = W * WireWidth * 0.5;
	float xDx = mod(vP.x + o, W);
	float yDx = mod(vP.y + o, W);
	float zDx = mod(vP.z + o, W);
	if (!xGrid) xDx = W;
	if (!yGrid) yDx = W;
	if (!zGrid) zDx = W;
	float minDx = min(min(xDx, yDx), zDx);
	if ( ( W * WireWidth) < minDx) discard;
	vec3 l = normalize(vL);
	vec3 n = normalize(vN);
	vec3 h = normalize(l+normalize(vV));
	vec3 backcolor = Ambient * vec3(0.1+0.1+0.1) + vClr.rgb * abs(dot(n,l)) * Diffuse;
	vec3 a = vClr.rgb * Ambient;
	vec3 d = vClr.rgb * dot(n,l) * Diffuse;
	float s = pow(max(0.0,dot(n,h)), Shininess) * Specular;
	float backface = step(0.00, n.z);
	color = vec4(mix(backcolor.rgb, a + d + s,  backface), 1.0);
}