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varying vec3 light_ss;
varying vec3 eye_ss;
varying vec2 uv_coord;
const vec3 base_color = vec3(1.0, 0.0, 0.0);
/* Specular exponent.
*/
uniform float s;
/* Adapted from the Orange Book, 3rd edition, chapter 11. */
vec3 perturbed_normal()
{
const float BumpDensity = 30.0;
const float BumpSize = 0.15;
/* The incoming texture coordinate (uv_coord) ranges from 0 to 1.
* Multiplying by BumpDensity gives coordinates between 0 and 30.
* Then, fract gives us a value from 0 to 1...and subtracting 0.5
* gives us a perturbation value between -0.5 and 0.5.
*/
vec2 c = BumpDensity * uv_coord;
vec2 p = fract(c) - vec2(0.5);
/* If not in a bump, return an unperturbed normal */
if (dot(p,p) >= BumpSize)
return vec3(0,0,1);
/* Otherwise, return the perturbed normal */
return normalize(vec3(p, 1));
}
void main(void)
{
vec3 l = normalize(light_ss);
vec3 v = normalize(eye_ss);
vec3 h = normalize(l + v);
vec3 n = perturbed_normal();
vec3 diff = base_color * dot(n, l);
float spec = pow(dot(n, h), s);
gl_FragColor = step(0.0, dot(n, l)) * vec4(diff + vec3(spec), 1.0);
}
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