varying vec3 r;
varying vec4 c;

#vertex

uniform vec3 eye;
uniform vec3 center;
uniform float factor;
uniform sampler2D spikemap;

float sample(in vec3 v) {
    vec3 r = v;
    vec3 a = abs(r);
    float m = max(a.x, max(a.y, a.z));
    vec2 o;
    r /= m;
         if (m == a.x) { r = r.yzx; o.x = 0.125; }
    else if (m == a.y) { r = r.xzy; o.x = 0.375; }
    else                           `o.x = 0.625;
    o.y = (r.z >= 0.0) ? 0.25 : 0.75;
    return texture2D(spikemap, o + r.xy * vec2(0.123076923076923, 0.246153846153846)).r;
}

vec3 trans(in vec3 v, in float e) {
    vec3 d = v - center;
    float r = length(d);
    return center + normalize(d) * mix(r, mix(r, 2.0, factor), e);
}

vec3 spike(in vec3 v) {
    return trans(normalize(v), sample(v));
}

void main() {
    vec4 p;
    vec3 n, t, b;
    float e;

    n = gl_Vertex.xyz;
    e = sample(n);
    p = vec4(trans(n, e), 1.0);
    t = vec3(n.y, -n.x, 0.0);
    t = 0.000621698996452716 * normalize(t - n * dot(n, t));
    //  ^^^ = 1 / (2 * pi * TEXSIZE)
    b = cross(n, t);
    n = normalize(cross(spike(n + t) - spike(n - t),
                        spike(n + b) - spike(n - b)));
    
    r = reflect(normalize(eye - p.xyz), n);

    c = abs(dot(normalize(gl_LightSource[0].position.xyz - vec3(gl_ModelViewMatrix * p)),
                normalize(gl_NormalMatrix * n)))
      * vec4(0.2, 0.0, 0.0, 0.0) + vec4(0.3, 0.0, 0.0, 1.0);
    e = 1.0 - e;
    c *= 1.0 - e * e;

    gl_Position = gl_ModelViewProjectionMatrix * p;
}

#fragment

uniform samplerCube cubemap;

void main() {
    gl_FragColor = c + textureCube(cubemap, r);
}