251 lines
6.7 KiB
C++
251 lines
6.7 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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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 "../debug.hpp"
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#include "../point.hpp"
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#include "../random.hpp"
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#include "../vector.hpp"
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#include <algorithm>
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using namespace util::noise;
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using util::range;
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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::vector2d
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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::vector2d (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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range<double>
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value<L>::bounds (void) const
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{ return { -1.0, 1.0 }; }
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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 = static_cast<intmax_t> (x);
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intmax_t y_int = static_cast<intmax_t> (y);
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double x_fac = x - x_int;
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double y_fac = y - y_int;
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// Shift the coordinate system down a little to ensure we get unit weights
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// for the lerp. It's better to do this than abs the fractional portion so
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// we don't get reflections along the origin.
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if (x < 0) { x_fac = 1.0 + x_fac; x_int -= 1; }
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if (y < 0) { y_fac = 1.0 + y_fac; y_int -= 1; }
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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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namespace util {
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namespace noise {
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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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}
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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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range<double>
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gradient<L>::bounds (void) const
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{ return { -sqrt(2.0) / 2.0, sqrt (2.0) / 2.0 }; }
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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 = static_cast<intmax_t> (x);
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intmax_t y_int = static_cast<intmax_t> (y);
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double x_fac = x - x_int;
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double y_fac = y - y_int;
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// Shift the coordinate system down a little to ensure we get unit weights
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// for the lerp. It's better to do this than abs the fractional portion so
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// we don't get reflections along the origin.
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if (x < 0) { x_fac = 1.0 + x_fac; x_int -= 1; }
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if (y < 0) { y_fac = 1.0 + y_fac; y_int -= 1; }
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// Generate the four corner values. It's not strictly necessary to
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// normalise the values, but we get a more consistent and visually
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// appealing range of outputs with normalised values.
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vector2d p0 = generate<vector2d> (x_int, y_int, this->seed).normalise ();
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vector2d p1 = generate<vector2d> (x_int + 1, y_int, this->seed).normalise ();
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vector2d p2 = generate<vector2d> (x_int, y_int + 1, this->seed).normalise ();
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vector2d p3 = generate<vector2d> (x_int + 1, y_int + 1, this->seed).normalise ();
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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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namespace util {
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namespace noise {
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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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}
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}
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///////////////////////////////////////////////////////////////////////////////
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cellular::cellular (seed_t _seed):
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basis (_seed)
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{ ; }
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cellular::cellular ()
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{ ; }
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range<double>
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cellular::bounds (void) const
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{ return { 0.0, 1.5 }; }
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double
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cellular::eval (double x, double y) const {
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using util::point2d;
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intmax_t x_int = static_cast<intmax_t> (x);
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intmax_t y_int = static_cast<intmax_t> (y);
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double x_fac = x - x_int;
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double y_fac = y - y_int;
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// Generate the four corner values. It's not strictly necessary to
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// normalise the values, but we get a more consistent and visually
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// appealing range of outputs with normalised values.
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if (x < 0) { x_fac = 1.0 + x_fac; x_int -= 1; }
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if (y < 0) { y_fac = 1.0 + y_fac; y_int -= 1; }
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// +---+---+---+
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// | 0 | 1 | 2 |
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// +---+---+---+
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// | 3 | 4 | 5 |
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// +---+-------+
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// | 6 | 7 | 8 |
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// +---+---+---+
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point2d centre = { x_fac, y_fac };
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double distances[9] = { std::numeric_limits<double>::quiet_NaN () };
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double *cursor = distances;
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for (signed y_off = -1; y_off <= 1 ; ++y_off)
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for (signed x_off = -1; x_off <= 1; ++x_off) {
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auto pos = point2d (double (x_off), double (y_off));
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auto off = generate<vector2d> (x_int + x_off, y_int + y_off, this->seed);
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off += 1.;
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off /= 2.;
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CHECK (off.x >= 0 && off.x <= 1.0);
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CHECK (off.y >= 0 && off.y <= 1.0);
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pos += off;
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*cursor++ = pos.distance2 (centre);
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}
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std::sort (std::begin (distances), std::end (distances));
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CHECK_GE (distances[0], 0);
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CHECK (bounds ().contains (distances[0]));
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return distances[0];
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}
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