149 lines
3.8 KiB
C++
149 lines
3.8 KiB
C++
/*
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* This file is part of libgim.
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*
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* libgim is free software: you can redistribute it and/or modify it under the
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* terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* libgim is distributed in the hope that it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License
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* along with libgim. If not, see <http://www.gnu.org/licenses/>.
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*
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* Copyright 2012 Danny Robson <danny@nerdcruft.net>
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*/
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#include "noise/basis.hpp"
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#include "noise/lut.hpp"
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#include "../vector.hpp"
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#include "../random.hpp"
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using namespace util::noise;
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///////////////////////////////////////////////////////////////////////////////
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// Generate a type from [-UNIT..UNIT]
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template <typename T>
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T
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generate (intmax_t x, intmax_t y, basis::seed_t);
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template <>
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double
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generate (intmax_t x, intmax_t y, basis::seed_t seed) {
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size_t idx = permute (x, y, seed);
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return LUT[idx];
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}
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template <>
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util::vector2
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generate (intmax_t x, intmax_t y, basis::seed_t seed) {
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auto u = permute (x, y, seed);
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auto v = permute (u ^ seed);
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return util::vector2 (LUT[u], LUT[v]);
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}
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///////////////////////////////////////////////////////////////////////////////
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basis::basis (seed_t _seed):
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seed (_seed)
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{ ; }
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basis::basis ():
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seed (util::random<seed_t> ())
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{ ; }
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basis::~basis ()
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{ ; }
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double
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basis::eval (double, double) const
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{ unreachable (); }
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///////////////////////////////////////////////////////////////////////////////
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template <lerp_function L>
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value<L>::value (seed_t _seed):
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basis (_seed)
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{ ; }
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template <lerp_function L>
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value<L>::value ()
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{ ; }
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template <lerp_function L>
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double
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value<L>::eval (double x, double y) const {
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intmax_t x_int = intmax_t (x);
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double x_fac = x - x_int;
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intmax_t y_int = intmax_t (y);
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double y_fac = y - y_int;
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// Generate the four corner values
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double p0 = generate<double> (x_int, y_int, this->seed);
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double p1 = generate<double> (x_int + 1, y_int, this->seed);
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double p2 = generate<double> (x_int, y_int + 1, this->seed);
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double p3 = generate<double> (x_int + 1, y_int + 1, this->seed);
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// Interpolate on one dimension, then the other.
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return L (L (p0, p1, x_fac),
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L (p2, p3, x_fac),
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y_fac);
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}
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template struct value<lerp::linear>;
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template struct value<lerp::cubic>;
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template struct value<lerp::quintic>;
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///////////////////////////////////////////////////////////////////////////////
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template <lerp_function L>
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gradient<L>::gradient (seed_t _seed):
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basis (_seed)
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{ ; }
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template <lerp_function L>
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gradient<L>::gradient ()
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{ ; }
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template <lerp_function L>
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double
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gradient<L>::eval (double x, double y) const {
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intmax_t x_int = intmax_t (x);
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double x_fac = x - x_int;
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intmax_t y_int = intmax_t (y);
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double y_fac = y - y_int;
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// Generate the four corner values
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vector2 p0 = generate<vector2> (x_int, y_int, this->seed);
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vector2 p1 = generate<vector2> (x_int + 1, y_int, this->seed);
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vector2 p2 = generate<vector2> (x_int, y_int + 1, this->seed);
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vector2 p3 = generate<vector2> (x_int + 1, y_int + 1, this->seed);
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double v0 = p0.x * x_fac + p0.y * y_fac;
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double v1 = p1.x * (x_fac - 1.0) + p1.y * y_fac;
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double v2 = p2.x * x_fac + p2.y * (y_fac - 1.0);
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double v3 = p3.x * (x_fac - 1.0) + p3.y * (y_fac - 1.0);
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return L (L (v0, v1, x_fac),
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L (v2, v3, x_fac),
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y_fac);
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}
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template struct gradient<lerp::linear>;
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template struct gradient<lerp::cubic>;
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template struct gradient<lerp::quintic>;
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