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// This file defines some utility functions.

#ifndef O3D_COMMAND_BUFFER_SAMPLES_BUBBLE_UTILS_H_
#define O3D_COMMAND_BUFFER_SAMPLES_BUBBLE_UTILS_H_

#include <math.h>
#include <stdlib.h>
#include <algorithm>

namespace o3d {
namespace command_buffer {

const float kPi = 3.14159265359f;

// Returns a random value between min and max.
inline float Randf(float min, float max, unsigned int *seed) {
  return min + (max - min) / RAND_MAX * rand_r(seed);
}

// Converts a [0..1] float to a [0..255] color value.
inline unsigned char ToChar(float x) {
  x = std::min(1.f, std::max(0.f, x));
  return static_cast<unsigned char>(x * 255.f);
}

// Maps [0..1] into [0..1], using a smooth (C^2) function,
// with f(0)=0, f(1)=1, f'(0)=f'(1)=0.
// This version is simply a cubic interpolation between 0 and 1.
inline float SmoothStep(float x) {
  return (3.f - 2.f * x) * x * x;
}

// Interpolates between a and b, with a ratio of t.
inline float Lerp(float t, float a, float b) {
  return a + (b-a)*t;
}

}  // namespace command_buffer
}  // namespace o3d

#endif  // O3D_COMMAND_BUFFER_SAMPLES_BUBBLE_UTILS_H_