//
// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) Contributors to the OpenEXR Project.
//


//-----------------------------------------------------------------------------
//
//	Functions that algorithmically generate images, so that
//	the code examples for image file reading and writing have
//	data they can work with.
//	Note that it is not necessary to study the code below in
//	order to understand how the file I/O code examples work.
//
//-----------------------------------------------------------------------------


#include "drawImage.h"

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

#include "namespaceAlias.h"
using namespace IMF;
using namespace std;

namespace
{

float
pw (float x, int y)
{
    float p = 1;

    while (y)
    {
	if (y & 1)
	    p *= x;

	x *= x;
	y >>= 1;
    }

    return p;
}


void
sp (Array2D<Rgba> &px, int w, int h,
    float xc, float yc, float rc,
    float rd, float gn, float bl, float lm)
{
    int x1 = int (max ((float) floor (xc - rc),  0.0f));
    int x2 = int (min ((float) ceil  (xc + rc), w - 1.0f));
    int y1 = int (max ((float) floor (yc - rc),  0.0f));
    int y2 = int (min ((float) ceil  (yc + rc), h - 1.0f));

    for (int y = y1; y <= y2; ++y)
    {
	for (int x = x1; x <= x2; ++x)
	{
	    float xl = (x - xc) / rc;
	    float yl = (y - yc) / rc;
	    float r  = sqrt (xl * xl + yl * yl);

	    if (r >= 1)
		continue;

	    float a = 1;

	    if (r * rc > rc - 1)
		a = rc - r * rc;

	    float zl = sqrt (1 - r * r);
	    float dl = xl * 0.42426 - yl * 0.56568 + zl * 0.70710;

	    if (dl < 0)
		dl *= -0.1;

	    float hl = pw (dl, 50) * 4;
	    float dr = (dl + hl) * rd;
	    float dg = (dl + hl) * gn;
	    float db = (dl + hl) * bl;

	    Rgba &p = px[y][x];
	    p.r = p.r * (1 - a) + dr * lm * a;
	    p.g = p.g * (1 - a) + dg * lm * a;
	    p.b = p.b * (1 - a) + db * lm * a;
	    p.a = 1 - (1 - p.a) * (1 - a);
	}
    }
}


void
zsp (Array2D<half> &gpx, Array2D<float> &zpx, int w, int h,
     float xc, float yc, float zc, float rc, float gn)
{
    int x1 = int (max ((float) floor (xc - rc),  0.0f));
    int x2 = int (min ((float) ceil  (xc + rc), w - 1.0f));
    int y1 = int (max ((float) floor (yc - rc),  0.0f));
    int y2 = int (min ((float) ceil  (yc + rc), h - 1.0f));

    for (int x = x1; x <= x2; ++x)
    {
	for (int y = y1; y <= y2; ++y)
	{
	    float xl = (x - xc) / rc;
	    float yl = (y - yc) / rc;
	    float r  = sqrt (xl * xl + yl * yl);

	    if (r >= 1)
		continue;

	    float zl = sqrt (1 - r * r);
	    float zp = zc - rc * zl;

	    if (zp >= zpx[y][x])
		continue;

	    float dl = xl * 0.42426 - yl * 0.56568 + zl * 0.70710;

	    if (dl < 0)
		dl *= -0.1;

	    float hl = pw (dl, 50) * 4;
	    float dg = (dl + hl) * gn;

	    gpx[y][x] = dg;
	    zpx[y][x] = zp;
	}
    }
}


inline float
z (float k)
{
    k = 2 * (k - int (k));
    return (k < 1)? k: 2 - k;
}


inline void
clear (Rgba &color)
{
    color.r = 0;
    color.g = 0;
    color.b = 0;
}


inline void
clear (GZ &gz)
{
    gz.g = 0;
    gz.z = 0;
}


void
add (float k, Rgba &color)
{
    color.a = k;
    k *= 4;
    color.r += 0.1f + 4 * z (k);
    color.g += 0.1f + 4 * z (k + .33333f);
    color.b += 0.1f + 4 * z (k + .66667f);
}


void
add (float k, GZ &gz)
{
    k *= 5;
    gz.g += 4 * z (k);
    gz.z = k;
}


inline void
scale (float f, Rgba &color)
{
    color.r *= f;
    color.g *= f;
    color.b *= f;
    color.a *= f;
}


inline void
scale (float f, GZ &gz)
{
    gz.g *= f;
    gz.z *= f;
}


template <class P>
void
mndl (Array2D <P> &px,
      int w, int h,
      int xMin, int xMax,
      int yMin, int yMax,
      int xSamples, int ySamples,
      double rMin,
      double rMax,
      double iMin,
      double aspect,
      double rSeed,
      double iSeed)
{
    if (xSamples > 6)
	xSamples = 6;

    if (ySamples > 6)
	ySamples = 6;

    double iMax = iMin + aspect * (rMax - rMin) * h / w;
    double sx = double (rMax - rMin) / w;
    double sy = double (iMax - iMin) / h;
    double tx = 1.f / xSamples;
    double ty = 1.f / ySamples;
    float  t  = tx * ty;

    for (int y = yMin; y < yMax; ++y)
    {
        for (int x = xMin; x < xMax; ++x)
        {
            P &p = px[y - yMin][x - xMin];

	    clear (p);

	    for (int i = 0; i < xSamples; ++i)
            {
		for (int j = 0; j < ySamples; ++j)
                {
                    const double a = rMin + sx * (x + i * tx);
		    const double b = iMin + sy * (y + j * ty);
		    const double sMax = 100;
		    const int kMax = 256;
                    double r = rSeed;
		    double i = iSeed;
		    double s = 0;
                    int k = 0;

                    while (k < kMax && s < sMax)
                    {
                        s = r * r - i * i;
                        i = 2 * r * i + b;
                        r = s + a;
                        k++;
                    }

		    add (k / float (kMax), p);
                }
            }

	    scale (t, p);
        }
    }
}

} // namespace


void
drawImage1 (Array2D<Rgba> &px, int w, int h)
{
    for (int y = 0; y < h; ++y)
    {
	for (int x = 0; x < w; ++x)
	{
	    Rgba &p = px[y][x];
	    p.r = 0;
	    p.g = 0;
	    p.b = 0;
	    p.a = 0;
	}
    }

    int n = 5600;

    for (int i = 0; i < n; ++i)
    {
	float t = (i * 2.0 * M_PI) / n;
	float xp = sin (t * 2.0) + 0.2 * sin (t * 15.0);
	float yp = cos (t * 3.0) + 0.2 * cos (t * 15.0);
	float r = float (i + 1) / float (n);
	float xq = xp + 0.3 * r * sin (t * 80.0);
	float yq = yp + 0.3 * r * cos (t * 80.0);
	float xr = xp + 0.3 * r * sin (t * 80.0 + M_PI / 2);
	float yr = yp + 0.3 * r * cos (t * 80.0 + M_PI / 2);

	if (i % 10 == 0)
	    sp (px, w, h,
		xp * w / 3 + w / 2, yp * h / 3 + h / 2,
		w * 0.05 * r,
		2.0, 0.8, 0.1,
		0.5 * r * r);

	sp (px, w, h,
	    xq * w / 3 + w / 2, yq * h / 3 + h / 2,
	    w * 0.01 * r,
	    0.7, 0.2, 2.0,
	    0.5 * r * r);

	sp (px, w, h,
	    xr * w / 3 + w / 2, yr * h / 3 + h / 2,
	    w * 0.01 * r,
	    0.2, 1.5, 0.1,
	    0.5 * r * r);
    }
}


void
drawImage2 (Array2D<half> &gpx, Array2D<float> &zpx, int w, int h)
{
    for (int y = 0; y < h; ++y)
    {
	for (int x = 0; x < w; ++x)
	{
	    gpx[y][x] = 0;
	    zpx[y][x] = FLT_MAX;
	}
    }

    int n = 2000;

    for (int i = 0; i < n; ++i)
    {
	float t = (i * 2.0 * M_PI) / n;
	float xp = sin (t * 4.0) + 0.2 * sin (t * 15.0);
	float yp = cos (t * 3.0) + 0.2 * cos (t * 15.0);
	float zp = sin (t * 5.0);
	float rd = 0.7 + 0.3 * sin (t * 15.0);
	float gn = 0.5 - 0.5 * zp + 0.2;

	zsp (gpx, zpx, w, h,
	     xp * w / 3 + w / 2,
	     yp * h / 3 + h / 2,
	     zp * w + 3 * w,
	     w * rd * 0.05,
	     2.5 * gn * gn);
    }
}


void
drawImage3 (Array2D<Rgba> &px,
            int w, int h,
            int xMin, int xMax,
            int yMin, int yMax,
            int xLevel, int yLevel)
{
    mndl (px,
	  w, h,
	  xMin, xMax,
	  yMin, yMax,
	  (1 << xLevel), (1 << yLevel),
	  0.328, 0.369,
	  0.5,
	  double (1 << yLevel) / double (1 << xLevel),
	  -0.713, 0.9738);
}


void
drawImage4 (Array2D<Rgba> &px,
            int w, int h,
            int xMin, int xMax,
            int yMin, int yMax,
            int xLevel, int yLevel)
{
    mndl (px,
	  w, h,
	  xMin, xMax,
	  yMin, yMax,
	  (1 << xLevel), (1 << yLevel),
	  0.3247, 0.33348,
	  0.4346,
	  double (1 << yLevel) / double (1 << xLevel),
	  0.4, -0.765);
}


void
drawImage5 (Array2D<Rgba> &px,
            int w, int h,
            int xMin, int xMax,
            int yMin, int yMax,
            int xLevel, int yLevel)
{
    mndl (px,
	  w, h,
	  xMin, xMax,
	  yMin, yMax,
	  (1 << xLevel), (1 << yLevel),
	  0.2839, 0.2852,
	  0.00961,
	  double (1 << yLevel) / double (1 << xLevel),
	  0.25, 0.31);
}


void
drawImage6 (Array2D<GZ> &px, int w, int h)
{
    mndl (px,
	  w, h,
	  0, w,
	  0, h,
	  3, 3,
	  -2.5, 1.0,
	  -1.3333,
	  1,
	  0, 0);
}


void
drawImage7 (Array<Rgba> &px, int w, int h, int y)
{
    for (int x = 0; x < w; ++x)
    {
	float xc = x - w / 2;
	float yc = y - h / 2;
	float a = atan2 (xc, yc);
	float r = sqrt (xc * xc + yc * yc);

	Rgba &p = px[x];
	p.r = sin (3.0f * a + 0.3f * sin (0.10f * r)) * 0.5f + 0.5f;
	p.g = sin (3.0f * a + 0.3f * sin (0.11f * r)) * 0.5f + 0.5f;
	p.b = sin (3.0f * a + 0.3f * sin (0.12f * r)) * 0.5f + 0.5f;
	p.a = 1;
    }
}
