/**
* gimp_vector3_normalize:
* @vector: a pointer to a #GimpVector3.
*
* Normalizes the @vector so the length of the @vector is 1.0. The nul
* vector will not be changed.
**/
void
gimp_vector3_normalize (GimpVector3 *vector)
{
gdouble len;
len = gimp_vector3_length (vector);
if (len != 0.0)
{
len = 1.0 / len;
vector->x *= len;
vector->y *= len;
vector->z *= len;
}
else
{
*vector = gimp_vector3_zero;
}
}
static GimpRGB
phong_shade (GimpVector3 *pos,
GimpVector3 *viewpoint,
GimpVector3 *normal,
GimpVector3 *light,
GimpRGB *diff_col,
GimpRGB *spec_col,
gint type)
{
GimpRGB ambientcolor, diffusecolor, specularcolor;
gdouble NL, RV, dist;
GimpVector3 L, NN, V, N;
/* Compute ambient intensity */
/* ========================= */
N = *normal;
ambientcolor = *diff_col;
gimp_rgb_multiply (&ambientcolor, mapvals.material.ambient_int);
/* Compute (N*L) term of Phong's equation */
/* ====================================== */
if (type == POINT_LIGHT)
gimp_vector3_sub (&L, light, pos);
else
L = *light;
dist = gimp_vector3_length (&L);
if (dist != 0.0)
gimp_vector3_mul (&L, 1.0 / dist);
NL = 2.0 * gimp_vector3_inner_product (&N, &L);
if (NL >= 0.0)
{
/* Compute (R*V)^alpha term of Phong's equation */
/* ============================================ */
gimp_vector3_sub (&V, viewpoint, pos);
gimp_vector3_normalize (&V);
gimp_vector3_mul (&N, NL);
gimp_vector3_sub (&NN, &N, &L);
RV = gimp_vector3_inner_product (&NN, &V);
RV = pow (RV, mapvals.material.highlight);
/* Compute diffuse and specular intensity contribution */
/* =================================================== */
diffusecolor = *diff_col;
gimp_rgb_multiply (&diffusecolor, mapvals.material.diffuse_ref);
gimp_rgb_multiply (&diffusecolor, NL);
specularcolor = *spec_col;
gimp_rgb_multiply (&specularcolor, mapvals.material.specular_ref);
gimp_rgb_multiply (&specularcolor, RV);
gimp_rgb_add (&diffusecolor, &specularcolor);
gimp_rgb_multiply (&diffusecolor, mapvals.material.diffuse_int);
gimp_rgb_clamp (&diffusecolor);
gimp_rgb_add (&ambientcolor, &diffusecolor);
}
return ambientcolor;
}
static GimpRGB
phong_shade (GimpVector3 *position,
GimpVector3 *viewpoint,
GimpVector3 *normal,
GimpVector3 *lightposition,
GimpRGB *diff_col,
GimpRGB *light_col,
LightType light_type)
{
GimpRGB diffuse_color, specular_color;
gdouble nl, rv, dist;
GimpVector3 l, v, n, lnormal, h;
/* Compute ambient intensity */
/* ========================= */
n = *normal;
/* Compute (N*L) term of Phong's equation */
/* ====================================== */
if (light_type == POINT_LIGHT)
gimp_vector3_sub (&l, lightposition, position);
else
{
l = *lightposition;
gimp_vector3_normalize (&l);
}
dist = gimp_vector3_length (&l);
if (dist != 0.0)
gimp_vector3_mul (&l, 1.0 / dist);
nl = MAX (0., 2.0 * gimp_vector3_inner_product (&n, &l));
lnormal = l;
gimp_vector3_normalize (&lnormal);
if (nl >= 0.0)
{
/* Compute (R*V)^alpha term of Phong's equation */
/* ============================================ */
gimp_vector3_sub (&v, viewpoint, position);
gimp_vector3_normalize (&v);
gimp_vector3_add (&h, &lnormal, &v);
gimp_vector3_normalize (&h);
rv = MAX (0.01, gimp_vector3_inner_product (&n, &h));
rv = pow (rv, mapvals.material.highlight);
rv *= nl;
/* Compute diffuse and specular intensity contribution */
/* =================================================== */
diffuse_color = *light_col;
gimp_rgb_multiply (&diffuse_color, mapvals.material.diffuse_int);
diffuse_color.r *= diff_col->r;
diffuse_color.g *= diff_col->g;
diffuse_color.b *= diff_col->b;
gimp_rgb_multiply (&diffuse_color, nl);
specular_color = *light_col;
if (mapvals.material.metallic) /* for metals, specular color = diffuse color */
{
specular_color.r *= diff_col->r;
specular_color.g *= diff_col->g;
specular_color.b *= diff_col->b;
}
gimp_rgb_multiply (&specular_color, mapvals.material.specular_ref);
gimp_rgb_multiply (&specular_color, rv);
gimp_rgb_add (&diffuse_color, &specular_color);
gimp_rgb_clamp (&diffuse_color);
}
gimp_rgb_clamp (&diffuse_color);
return diffuse_color;
}