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#version 120
#define I965_HACK 1
varying vec3 light_surf;
varying vec3 eye_surf;
varying vec3 tangent_surf;
varying vec4 shadow_coords;
varying vec2 texcoord;
uniform sampler2D normal_sampler;
uniform sampler2D heightmap_sampler;
uniform sampler2DShadow shadow_sampler;
uniform float F0, ni, ward_mm_inv, ward_mn_inv, ward_nn_inv;
float schlick_fresnel(float n_dot_l)
{
return F0 + (1 - F0) * pow(1 - n_dot_l, 5);
}
void main()
{
float shadow = shadow2DProj(shadow_sampler, shadow_coords).x;
const vec4 material_color = vec4(0.7, 0.5, 0.3, 0.0);
vec4 color;
float s = .7;
float d = 1 - s;
float Ii = 0.9; /*intensity of incoming light */
float Iia = .1 * Ii; /*intensity of ambient light */
float Rs = 0;
float D;
float Rd = (1 - F0) * 2;
/* Calculate ambient lighting. */
/* Ambient occlusion factor -- sample the height map we
* used to generate the normal map, and reduce intensity in
* the valleys.
*/
float heightmap = texture2D(heightmap_sampler, texcoord).x;
float Ra = Rd * (.8 + .2 * heightmap);
color = material_color * Iia * Ra;
/* Calculate specular and diffuse lighting */
#if !I965_HACK
if (shadow > 0) {
#endif
vec3 l = normalize(light_surf);
vec3 v = normalize(eye_surf);
vec3 h = normalize(l + v);
vec3 t = normalize(tangent_surf);
vec3 n = texture2D(normal_sampler, texcoord).xyz * 2 - 1;
/* Hack: Reduce the significance of our normal map, which
* otherwise looks incongruous with the straight edges.
*/
n = normalize(n + vec3(0,0,1));
float n_dot_l = dot(n, l);
float n_dot_v = dot(n, v);
float n_dot_h = dot(n, h);
float v_dot_h = dot(v, h);
float cos2_alpha = n_dot_h * n_dot_h;
float tan2_alpha = (1 - cos2_alpha) / cos2_alpha;
/* Aniso BRDF from Ward's "Measuring and Modeling
* Anisotropic Reflection".
*/
/* Make phi be the angle between the projections of
* the tangent and half-angle vectors onto the
* surface plane (z=0). Doing it right would involve
* projecting onto the plane defined by n.
*/
float cos_phi = dot(normalize(t.xy), normalize(h.xy));
float cos2_phi_over_m2 = (cos_phi * cos_phi) * ward_mm_inv;
float sin2_phi_over_n2 = (1 - cos_phi * cos_phi) * ward_nn_inv;
D = exp(-tan2_alpha * (cos2_phi_over_m2 + sin2_phi_over_n2));
Rs = 2 * schlick_fresnel(n_dot_l) * D *
inversesqrt(n_dot_l * n_dot_v) * ward_mn_inv;
Rs *= s;
color += max(0, n_dot_l) * step(0, n_dot_v) *
vec4(material_color.xyz *
((Rd * d + Rs) * Ii * shadow),
material_color.w);
#if !I965_HACK
}
#endif
gl_FragColor = color;
/* Debugging scalars -- Map [0,1] to [0.5,1] to catch negative
* values. Multiply by the step function to catch when
* the scalar won't come into play because Rs == 0.
*/
#if 0
/* Constant visualization */
gl_FragColor = vec4(vec3(F0 / 2 + .5), 1);
#endif
#if 0
/* Normal visualization */
gl_FragColor = vec4((normal.x + 1) / 2,
(normal.y + 1) / 2,
(normal.z + 1) / 2,
0);
#endif
#if 0
/* Sampler visualization */
gl_FragColor = texture2D(normal_sampler, texcoord);
#endif
}
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