T Evaluate(const DifferentialGeometry &dg) const {
Vector dpdx, dpdy;
Point P = mapping->Map(dg, &dpdx, &dpdy);
float windStrength =
FBm(.1f * P, .1f * dpdx, .1f * dpdy, .5f, 3);
float waveHeight =
FBm(P, dpdx, dpdy, .5f, 6);
return fabsf(windStrength) * waveHeight;
}
Spectrum Evaluate(const DifferentialGeometry &dg) const {
Vector dpdx, dpdy;
Point P = mapping->Map(dg, &dpdx, &dpdy);
P *= scale;
float marble = P.y + variation * FBm(P, scale * dpdx,
scale * dpdy, omega, octaves);
float t = .5f + .5f * sinf(marble);
// Evaluate marble spline at _t_
static float c[][3] = { { .58f, .58f, .6f }, { .58f, .58f, .6f }, { .58f, .58f, .6f },
{ .5f, .5f, .5f }, { .6f, .59f, .58f }, { .58f, .58f, .6f },
{ .58f, .58f, .6f }, {.2f, .2f, .33f }, { .58f, .58f, .6f },
};
#define NC sizeof(c) / sizeof(c[0])
#define NSEG (NC-3)
int first = Floor2Int(t * NSEG);
t = (t * NSEG - first);
Spectrum c0(c[first]), c1(c[first+1]), c2(c[first+2]), c3(c[first+3]);
// Bezier spline evaluated with de Castilejau's algorithm
Spectrum s0 = (1.f - t) * c0 + t * c1;
Spectrum s1 = (1.f - t) * c1 + t * c2;
Spectrum s2 = (1.f - t) * c2 + t * c3;
s0 = (1.f - t) * s0 + t * s1;
s1 = (1.f - t) * s1 + t * s2;
// Extra scale of 1.5 to increase variation among colors
return 1.5f * ((1.f - t) * s0 + t * s1);
}
T Evaluate(const DifferentialGeometry &dg) const {
Vector dpdx, dpdy;
Point P = mapping->Map(dg, &dpdx, &dpdy);
return FBm(P, dpdx, dpdy, omega, octaves);
}
