Kayne Ruse
86 lines
2.4 KiB
C++
86 lines
2.4 KiB
C++
/* Copyright: (c) Kayne Ruse 2014
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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*
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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*
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* 3. This notice may not be removed or altered from any source
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* distribution.
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*/
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#include "perlin_noise.hpp"
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#include "vector2.hpp"
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#include <cmath>
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//-------------------------
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//Public access members
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//-------------------------
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double SimpleRNG::operator()(double x) {
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return (x + seed) * 345589144.0 + 1123581321.0;
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};
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Vector2 PerlinNoise::Gradient(Vector2 pos) {
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//could cache this result
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double angle = rng(pos.x * pos.y + pos.y);
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Vector2 v(cos(angle), sin(angle));
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v.Normalize();
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return v;
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}
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double PerlinNoise::Noise(double x, double y, double width, double height) {
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Vector2 queryPoint = {x, y};
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//calc the region's position
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x = Snap(x, width);
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y = Snap(y, height);
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//determine the grid points
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Vector2 tl = {x, y};
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Vector2 tr = {x + width, y};
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Vector2 bl = {x, y + height};
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Vector2 br = {x + width, y + height};
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//influence equasion
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double s = ScalarProduct(Gradient(tl), queryPoint - tl);
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double t = ScalarProduct(Gradient(tr), queryPoint - tr);
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double u = ScalarProduct(Gradient(bl), queryPoint - bl);
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double v = ScalarProduct(Gradient(br), queryPoint - br);
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//get the noise
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double a = s + Curve((t - s) / width);
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double b = u + Curve((v - u) / width);
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return a + Curve((b - a) / height);
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}
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//-------------------------
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//Static utility functions
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//-------------------------
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double PerlinNoise::Curve(double x) {
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//param: 0 to 1 inclusive
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return 3.0 * pow(x, 2.0) - 2.0 * pow(x, 3.0);
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}
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double PerlinNoise::Snap(double x, double base) {
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//snap to a grid (floating point version)
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return floor(x / base) * base;
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}
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double PerlinNoise::ScalarProduct(Vector2 lhs, Vector2 rhs) {
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//the dot product
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return lhs.x * rhs.x + lhs.y * rhs.y;
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} |