corona.cpp

/*
 * This file is released under the GNU General Public Licence
 *
 * authors:
 * Richard Ashbury       <richard.asbury@btinternet.com>
 * Jean-Christophe Hoelt <jeko@ios-software.com>
 */

/////////////////////////////////////////////////////////////////////////////
//
// Corona.cpp : Implementation of CCorona
//
/////////////////////////////////////////////////////////////////////////////

#include "corona.h"
#include <cstdlib>
#include <cmath>


/////////////////////////////////////////////////////////////////////////////
// Corona::Corona
// Constructor

Corona::Corona()
{
  m_clrForeground = 0x0000FF;
  m_swirltime     = 0;
  m_testing       = false;
  m_silent        = false;
  m_avg           = 1;
  m_oldval        = 0;
  m_pos           = 0;

  m_image         = 0;
  m_real_image    = 0;
  m_deltafield    = 0;
  m_width         = -1;
  m_height        = -1;
  m_real_height   = -1;
  nbParticules    = 1000;
  m_reflArray     = 0;
  m_waveloop      = 0.0;
  m_nPreset       = PRESET_CORONA;

  m_particles = (Particle*)calloc (nbParticules, sizeof(Particle));
  // Create particles in random positions
  for (int i = nbParticules - 1; i >= 0; --i)
  {
    Particle *it = m_particles + i;
    it->x = random(0, 1);
    it->y = random(0, 1);
    it->xvel = it->yvel = 0;
  }
  // Set up the background swirling effect
  chooseRandomSwirl();
}

/////////////////////////////////////////////////////////////////////////////
// Corona::~Corona
// Destructor

Corona::~Corona()
{
  if (m_real_image) free(m_real_image);
  if (m_deltafield) free(m_deltafield);
}

double Corona::random(double min, double max) const {
  return rand() * (max - min) / RAND_MAX + min;
}

bool Corona::setUpSurface(int width, int height) {
  // Delete any image that might have previously been allocated
  if (m_real_image) free(m_real_image);
  if (m_deltafield) free(m_deltafield);
  if (m_reflArray)  free(m_reflArray);

  // Fill in the size details in the BitmapInfo structure
  m_width  = width;
  m_height = (height*4) / 5;
  m_real_height = height;

  // Allocate the image data
  m_real_image = (unsigned char *)calloc(1,width*height+1);
  if (m_real_image == 0) return false;
  m_image      = m_real_image + m_width * (m_real_height - m_height);
  m_reflArray  = (int*)calloc(1,m_real_height - m_height + 1);

  // Allocate the delta-field memory, and initialise it
  m_deltafield = (unsigned char**)malloc(m_width * m_height * sizeof(unsigned char*));

  for (int x = 0; x < m_width; ++x) {
    for (int y = 0; y < m_height; ++y) {
      setPointDelta(x, y);
    }
  }

  // Change the number of particles
  int newsize = (int) (::sqrt(m_width * m_height) * 3.0);
  if (newsize < 2000) newsize = 2000;
  int oldsize = (int) nbParticules;
  nbParticules = newsize;
  m_particles = (Particle*)realloc (m_particles, sizeof(Particle) * newsize);
  for (int i = oldsize; i < newsize; ++i) {
    m_particles[i].x = random(0, 1);
    m_particles[i].y = random(0, 1);
    m_particles[i].xvel = m_particles[i].yvel = 0;
  }

  return true;
}

void Corona::drawLine(int x0, int y0, int x1, int y1, unsigned char col)
{
  int incx = (x1 > x0) ? 1 : -1;
  int incy = (y1 > y0) ? m_width : -m_width;
  int dincx = 2 * abs(y1 - y0);
  int dincy = 2 * abs(x1 - x0);
  unsigned char* p = &(m_image[x0 + y0 * m_width]);
  unsigned char* const end = &(m_image[m_width + (m_height - 1) * m_width]);
  unsigned char* const start = m_image;
  int n, d;	// n is the "pixel counter"

  // Always draw at least one pixel
  if (start <= p && p < end) *p = col;

  if (abs(x1 - x0) > abs(y1 - y0)) {
    d = x0 - x1;
    for (n = abs(x1 - x0); n > 0; --n, p += incx) {
      if (start <= p && p < end) *p = col;
      d += dincx;
      if (d > 0) {
        p += incy;
        d -= dincy;
      }
    }
  }
  else {
    d = y0 - y1;
    for (n = abs(y1 - y0); n > 0; --n, p += incy) {
      if (start <= p && p < end) *p = col;
      d += dincy;
      if (d > 0) {
        p += incx;
        d -= dincx;
      }
    }
  }
}


void Corona::chooseRandomSwirl()
{
  m_swirl.x = random(0.2, 0.8);
  m_swirl.y = random(0.2, 0.8);
  m_swirl.tightness = random(-0.01, 0.01);
  m_swirl.pull = random(1.0, 1.04);
}

void Corona::setPointDelta(int x, int y)
{
  double tx  = ((double) x / m_width)  - m_swirl.x;
  double ty  = ((double) y / m_height) - m_swirl.y;
  double d   = tx * tx + ty * ty;
  double ds  = ::sqrt(d);
  double ang = atan2(ty, tx) + m_swirl.tightness / (d + 0.01);
  int dx = (int) ((ds * m_swirl.pull * cos(ang) - tx) * m_width) + rand()  % 5 - 2;
  int dy = (int) ((ds * m_swirl.pull * sin(ang) - ty) * m_height) + rand() % 5 - 2;
  if (x + dx < 0) dx = -dx - x;
  if (x + dx >= m_width) dx = 2 * m_width - 2 * x - dx - 1;
  if (y + dy < 0) dy = -dy - y;
  if (y + dy >= m_height) dy = 2 * m_height - 2 * y - dy - 1;
  m_deltafield[x + y * m_width] = &(m_image[x + dx + (y + dy) * m_width]);
}

void Corona::applyDeltaField(bool heavy)
{
  if (heavy) {
    for (int y = 0; y < m_height; ++y) {
      unsigned char *s = &(m_image[y * m_width]);
      unsigned char **p = &(m_deltafield[y * m_width]);
      for (int x = 0; x < m_width; ++x, ++s, ++p) {
        *s = (*s + *(*p)) >> 1;
        if (*s >= 2) *s -= 2;
      }
    }
  }
  else {
    for (int y = 0; y < m_height; ++y) {
      unsigned char *s = &(m_image[y * m_width]);
      unsigned char **p = &(m_deltafield[y * m_width]);
      for (int x = 0; x < m_width; ++x, ++s, ++p) {
        *s = (*s + **p) >> 1;
        if (*s >= 1) *s -= 1;
      }
    }
  }
}

int Corona::getBeatVal(TimedLevel *tl)
{
  int total = 0;
  for (int i = 50; i < 250; ++i) {
    int n = tl->frequency[0][i];
    total += n;
  }
  total /= 3;

  m_avg = 0.9 * m_avg + 0.1 * total;
  if (m_avg < 1000) m_avg = 1000;

  if (total > m_avg * 1.2 && tl->timeStamp - tl->lastbeat > 750000) {
    m_avg = total;
    tl->lastbeat = tl->timeStamp;
    if (total > 2500) return 2500;
    else return total;
  }
  else return 0;
}

void Corona::drawParticules()
{
  int p;
  for (p = 0; p < nbParticules; ++p) {
    Particle *it = m_particles + p;
    int x = (int) (it->x * m_width);
    int y = (int) (it->y * m_height);
    int xv = (int) (it->xvel * m_width);
    int yv = (int) (it->yvel * m_height);
    drawLine(x, y, x - xv, y - yv, 255);
  }
}

void Corona::drawParticulesWithShift()
{
  int p;
  for (p = 0; p < nbParticules; ++p) {
    Particle *it = m_particles + p;
    int x = (int) (it->x * m_width);
    int y = (int) (it->y * m_height);
    int xv = (int) (it->xvel * m_width);
    int yv = (int) (it->yvel * m_height);
    double l = (xv * xv + yv * yv);
    if (l > 10.0 * 10.0) {
      l = ::sqrt(l);
      double dl = 10 / (l + 0.01);
      xv = (int) (xv * dl);
      yv = (int) (yv * dl);
    }
    drawLine(x, y, x - xv, y - yv, 255);
  }
}

void Corona::getAvgParticlePos(double& x, double& y) const
{
  x = y = 0;
  for (int i = 0; i < 10; ++i) {
    int r = rand() % nbParticules;
    x += m_particles[r].x;
    y += m_particles[r].y;
  }
  x /= 10;
  y /= 10;
}

#define REFL_MIN_WIDTH 3.0
#define REFL_INC_WIDTH 0.08

void Corona::genReflectedWaves(double loop)
{
  double fdec   = 0.0;
  double floop  = 0.0;
  double fwidth = (m_real_height - m_height) * REFL_INC_WIDTH + REFL_MIN_WIDTH;
  double REFL_MAX_WIDTH = fwidth;

  m_reflArray = new int[m_real_height - m_height + 1];
  
  for (int i = 0; i < (m_real_height - m_height); ++i)
  {
    double fincr = (3.1415 / 2.0) * (1.0 - (fwidth - REFL_MIN_WIDTH) / REFL_MAX_WIDTH);
    floop  += fincr;

    fwidth -= REFL_INC_WIDTH;
    fdec    = fwidth * sin(floop + loop);
    m_reflArray[i] = (int)fdec;
  }
}

void Corona::drawReflected()
{
  genReflectedWaves(m_waveloop);
  int offsetDest  = (m_real_height - m_height - 1) * m_width;
  int offsetSrc   = (m_real_height - m_height)     * m_width;

  for (int i = m_real_height - m_height; i--;)
  {
    int idec = m_reflArray[i];

    for (int x = m_width; x--;)
    {
      int out = m_real_image[(offsetSrc++) + idec];
      m_real_image[offsetDest++] = out;
    }

    offsetDest -= m_width * 2;
    offsetSrc  += m_width;
  }
}

void Corona::blurImage()
{
  for (int y = 1; y < m_real_height - 1; ++y) {
    m_real_image[y * m_width] = 0;
    for (int x = 1; x < m_width - 1; ++x) {
      int n = x + y * m_width;
      int val = m_real_image[n + 1];
      val += m_real_image[n - 1];
      val += m_real_image[n - m_width];
      val += m_real_image[n + m_width];
      val >>= 2;
      m_real_image[n] = val & 0xff;
    }
  }
}

void Corona::update(TimedLevel *pLevels)
{
  // Check for a beat
  int beatval = getBeatVal(pLevels);
  if (beatval > 1000)
  {
    int total = 0;
    for (int i = 0; i < 512; ++i)
      total += 2 * pLevels->frequency[0][i];
    double currval = 1.0 - exp(-total / 40000.0);
    m_oldval = (m_oldval + currval) / 2.0;

    double tx, ty;
    getAvgParticlePos(tx, ty);
    // If most of the particles are low down, use a launch
    if (ty < 0.2 && rand() % 4 != 0) {
      int p;
      double bv = m_oldval * 5.0;
      for (p = 0; p < nbParticules; ++p)
      {
        Particle *it = m_particles + p;
        if (it->y < 0.1) {
          double x = (it->x - tx) / bv;
          it->yvel += 0.01 * bv * exp(-1000.0 * x * x);
        }
      }
    }
    else
    {	// Otherwise use a swirl
      tx += random(-0.1, 0.1);
      ty += random(-0.1, 0.1);
      double bv = 0.009 * m_oldval;
      double bv2 = 0.0036 * m_oldval;
      if (rand() % 2 == 0) bv = -bv;
      m_movement.x = tx;
      m_movement.y = ty;
      m_movement.tightness = random(0.8 * bv, bv);
      m_movement.pull = random(1 - bv2, 1 - 0.2 * bv2);
      m_swirltime = 1;
    }

    pLevels->lastbeat = pLevels->currentTimeMs;
  }

  // Deal with the particles
  int p;
  for (p = 0; p < nbParticules; ++p)
  {
    Particle *it = m_particles + p;
    // Apply gravity
    it->yvel -= 0.0006;		// the gravity value

    // If there's an active swirl, swirl around it
    if (m_swirltime > 0) {
      double dx = it->x - m_movement.x;
      double dy = it->y - m_movement.y;
      double d = dx * dx + dy * dy;
      double ds = ::sqrt(d);
      double ang = atan2(dy, dx) + m_movement.tightness / (d + 0.01);
      it->xvel += (ds * m_movement.pull * cos(ang) - dx);
      it->yvel += (ds * m_movement.pull * sin(ang) - dy);
    }

    // Gitter
    it->xvel += random(-0.0002, 0.0002);
    it->yvel += random(-0.0002, 0.0002);

    // Clamp the velocity
    if (it->xvel < -0.1 ) it->xvel = -0.1;
    if (it->xvel > 0.1 ) it->xvel = 0.1;
    if (it->yvel < -0.1 ) it->yvel = -0.1;
    if (it->yvel > 0.1 ) it->yvel = 0.1;

    // Randomly move the particle once in a while
    if (rand() % (nbParticules / 5) == 0)
    {
      it->x = random(0, 1);
      it->y = random(0, 1);
      it->xvel = it->yvel = 0;
    }

    // Move and bounce the particle
    it->x += it->xvel;
    it->y += it->yvel;
    if (it->x < 0) { it->x = -it->x; it->xvel *= -0.25; it->yvel *= 0.25; }
    if (it->y < 0) { it->y = -it->y; it->xvel *= 0.25; it->yvel *= -0.25; }
    if (it->x > 1) { it->x = 2.0 - it->x; it->xvel *= -0.25; it->yvel *= 0.25; }
    if (it->y > 1) { it->y = 2.0 - it->y; it->xvel *= 0.25; it->yvel = 0; }
  }

  if (m_swirltime > 0) --m_swirltime;

  // Randomly change the delta field
  if (rand() % 200 == 0) chooseRandomSwirl();

  // Animate the waves
  m_waveloop += 0.6;
  
  // drawing.
  if (m_image != 0)
  {
    // Draw the particles on the bitmap
    drawParticules();

    // Apply the deltafield and update a few of its points
    applyDeltaField((m_nPreset == PRESET_BLAZE) && m_width * m_height < 150000); 

    int n = (m_width * m_height) / 100;
    for (int i = 0; i < n; ++i)
      setPointDelta(rand() % m_width, rand() % m_height);

    // If on the blaze preset, draw the particles again
    if (m_nPreset == PRESET_BLAZE)
      drawParticules();

    drawReflected();
    
    // Blur the bitmap
    blurImage();

    // If on the blaze preset, draw the particles one last time
    if (m_nPreset == PRESET_BLAZE)
      drawParticulesWithShift();
  }
}