Rendering/DayNight

In World of Warcraft, the DayNight system governs most of the general appearance of the world.

Things like area lighting, zone lighting, clouds, the sky sphere (ie the color gradient of the sky), stars (ie sky boxes) are all managed by DayNight.

DayNight::DarkenColor

CImVector DayNight::DarkenColor(CImVector const &clr, float amount) {

  C3Vector rgb;
  C3Vector hsv;

  rgb.x = clr->r / 255.0;
  rgb.y = clr->g / 255.0;
  rgb.z = clr->b / 255.0;

  hsv.x = 0.0;
  hsv.y = 0.0;
  hsv.z = 0.0;

  RGBtoHSV(&rgb, &hsv);

  hsv.z = hsv.z * amount;

  HSVtoRGB(&hsv, &rgb);

  CImVector result;

  CImVector::operator=(&result, &rgb);

  return result;

}

DayNight::SetDirection

DayNight::SetDirection calculates a C3Vector containing the direction vector for the global light, aka sunDir.

This direction vector is transformed by the view matrix prior to being uploaded to the shader.

void DayNight::SetDirection() {

  // Phi Table
  if ( !(dword_D39104 & 1) ) {

    dword_D39104 |= 1u;

    DayNight::phiTable = {

      { 0.0,  2.2165682 },
      { 0.25, 1.9198623 },
      { 0.5,  2.2165682 },
      { 0.75, 1.9198623 }

    };

  }

  // Theta Table
  if ( !(dword_D39104 & 2) ) {

    dword_D39104 |= 2;
    
    DayNight::thetaTable = {

      { 0.0,  3.926991 },
      { 0.25, 3.926991 },
      { 0.5,  3.926991 },
      { 0.75, 3.926991 }

    };

  }

  // D38B04: float DNInfo->dayProgression (0.0 to 1.0)
  float phi = DayNight::InterpTable(&DayNight::phiTable, 4u, flt_D38B04);
  float theta = DayNight::InterpTable(&DayNight::thetaTable, 4u, flt_D38B04);

  // Convert from spherical coordinates to XYZ
  // x = rho * sin(phi) * cos(theta)
  // y = rho * sin(phi) * sin(theta)
  // z = rho * cos(phi)

  float sinPhi = CMath::sinoid(phi);
  float cosPhi = CMath::cosoid(phi);

  float sinTheta = CMath::sinoid(theta);
  float cosTheta = CMath::cosoid(theta);

  // D38C9C: C3Vector sunDir
  dword_D38C9C.x = sinPhi * cosTheta;
  dword_D38C9C.y = sinPhi * sinTheta;
  dword_D38C9C.z = cosPhi;

}

DayNight::SetLightColors

void DayNight::SetLightColors() {

  // Light colors

  DayNight::g_dnInfo.lightInfo.dirColor = DayNight::g_dnInfo.light.dirColor;

  DayNight::g_dnInfo.lightInfo.ambColor = DayNight::g_dnInfo.light.ambColor;

  // Window light colors
  // MOMT.flags & F_WINDOW

  CImVector windowDirColor = DayNight::g_dnInfo.light.dirColor;

  CImVector::Blend255_(&windowDirColor, 128u, &DayNight::g_dnInfo.light.ambColor);

  CImVector windowAmbColor = DayNight::g_dnInfo.light.ambColor;

  CImVector::Blend255_(&windowAmbColor, 128u, &DayNight::g_dnInfo.light.dirColor);

  windowAmbColor.r = std::min(windowAmbColor.r, 16u);
  windowAmbColor.g = std::min(windowAmbColor.g, 16u);
  windowAmbColor.b = std::min(windowAmbColor.b, 16u);
  windowAmbColor.a = windowAmbColor.a - 1;            // 0 wraps to 255

  DayNight::g_dnInfo.lightInfo.windowDirColor = windowDirColor;

  DayNight::g_dnInfo.lightInfo.windowAmbColor = windowAmbColor;

  // Shadow color
  // TODO: Clean up

  int v1;

  BYTE1(v1) = (unsigned __int16)(85 * (DayNight::g_dnInfo.light.ambColor.r + 3)) >> 8;
  LOBYTE(v1) = (unsigned __int16)(85 * (DayNight::g_dnInfo.light.ambColor.g + 3)) >> 8;
  DayNight::g_dnInfo.shadowColor = (CImVector)(*(_DWORD *)&DayNight::g_dnInfo.light.ambColor & 0xFF000000 | ((unsigned __int16)(85 * (DayNight::g_dnInfo.light.ambColor.b + 3)) >> 8) | ((unsigned __int16)v1 << 8));
  DayNight::g_dnInfo.shadowColor.a = DayNight::g_dnInfo.light.shadowOpacity.r;

  // TODO: What is unkLightInfo?

  DayNight::g_dnInfo.unkLightInfo.dir.x = DayNight::g_dnInfo.lightInfo.dir.x;
  DayNight::g_dnInfo.unkLightInfo.dir.y = DayNight::g_dnInfo.lightInfo.dir.y;
  DayNight::g_dnInfo.unkLightInfo.dir.z = DayNight::g_dnInfo.lightInfo.dir.z;

  DayNight::g_dnInfo.unkLightInfo.dirColor = DayNight::g_dnInfo.light.dirColor;

  DayNight::g_dnInfo.unkLightInfo.ambColor = DayNight::g_dnInfo.light.ambColor;

  DayNight::g_dnInfo.unkLightInfo.windowDirColor = DayNight::g_dnInfo.lightInfo.windowDirColor;

  DayNight::g_dnInfo.unkLightInfo.windowAmbColor = DayNight::g_dnInfo.lightInfo.windowAmbColor;

  DayNight::g_dnInfo.unkLightInfo.shaderShadowColor.x = DayNight::g_dnInfo.lightInfo.shaderShadowColor.x;
  DayNight::g_dnInfo.unkLightInfo.shaderShadowColor.y = DayNight::g_dnInfo.lightInfo.shaderShadowColor.y;
  DayNight::g_dnInfo.unkLightInfo.shaderShadowColor.z = DayNight::g_dnInfo.lightInfo.shaderShadowColor.z;
  DayNight::g_dnInfo.unkLightInfo.shaderShadowColor.w = DayNight::g_dnInfo.lightInfo.shaderShadowColor.w;

  // Shader shadow color

  C3Vector rgb;

  rgb.x = DayNight::g_dnInfo.light.ambColor.r / 255.0f;
  rgb.y = DayNight::g_dnInfo.light.ambColor.g / 255.0f;
  rgb.z = DayNight::g_dnInfo.light.ambColor.b / 255.0f;

  C3Vector hsv;

  hsv.x = 0.0;
  hsv.y = 0.0;
  hsv.z = 0.0;

  RGBtoHSV(&rgb, &hsv);

  hsv.y = hsv.y * 0.33000001;
  hsv.z = hsv.z * 1.25;

  HSVtoRGB(&hsv, &rgb);

  DayNight::g_dnInfo.lightInfo.shaderShadowColor.x = rgb.x;
  DayNight::g_dnInfo.lightInfo.shaderShadowColor.y = rgb.y;
  DayNight::g_dnInfo.lightInfo.shaderShadowColor.z = rgb.z;
  DayNight::g_dnInfo.lightInfo.shaderShadowColor.w = 1.0;

}