core.hpp

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/* Copyright (c) 2023 Otto Link. Distributed under the terms of the GNU General
   Public License. The full license is in the file LICENSE, distributed with
   this software. */
 
#pragma once
#include <cmath>
#include <cstdint>
 
namespace hmap
{
 
float abs_smooth(float a, float mu);
 
float almost_unit_identity(float x);
 
float almost_unit_identity_c2(float x);
 
inline float approx_hypot(float a, float b)
{
  a = std::abs(a);
  b = std::abs(b);
  if (a > b) std::swap(a, b);
  return 0.414f * a + b;
}
 
inline float approx_rsqrt(float a)
{
  union
  {
    float    f;
    uint32_t i;
  } conv = {.f = a};
 
  conv.i = 0x5f3759df - (conv.i >> 1);
  conv.f *= 1.5F - (a * 0.5F * conv.f * conv.f);
 
  return conv.f;
}
 
int ceil_div(int a, int b);
 
float fast_exp(float x);
 
float fast_log(float x);
 
float gain(float x, float factor);
 
int highest_power_of_2(int n);
 
float lerp(float a, float b, float t);
 
float power_curve(float x, float a, float b);
 
float r_min(float f1, float f2, float alpha = 0.f);
 
float r_max(float f1, float f2, float alpha = 0.f);
 
float sigmoid(float x,
              float width = 1.f,
              float vmin = 0.f,
              float vmax = 1.f,
              float x0 = 0.f);
 
float smoothstep3(float x);
 
float smoothstep3_lower(float x);
 
float smoothstep3_upper(float x);
 
float smoothstep5(float x);
 
float smoothstep5_lower(float x);
 
float smoothstep5_upper(float x);
 
float smoothstep7(float x);
 
float threshold(float x, float x0, float x1);
 
float threshold_smooth(float x, float x0, float x1);
 
float trapeze(float x, float x0, float x1, float width);
 
float trapeze_smooth(float x, float x0, float x1, float width);
 
float triangle(float x, float vmin, float vmax);
 
} // namespace hmap