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::SetDirection

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

void DayNight::SetDirection() {

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

    dword_D39104 |= 1u;

    DayNight::phiTable[0].x = 0.0;   DayNight::phiTable[0].y = 2.2165682;
    DayNight::phiTable[1].x = 0.25;  DayNight::phiTable[1].y = 1.9198623;
    DayNight::phiTable[2].x = 0.5;   DayNight::phiTable[2].y = 2.2165682;
    DayNight::phiTable[3].x = 0.75;  DayNight::phiTable[3].y = 1.9198623;

  }

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

    dword_D39104 |= 2;
    
    DayNight::thetaTable[0].x = 0.0;   DayNight::thetaTable[0].y = 3.926991;
    DayNight::thetaTable[1].x = 0.25;  DayNight::thetaTable[1].y = 3.926991;
    DayNight::thetaTable[2].x = 0.5;   DayNight::thetaTable[2].y = 3.926991;
    DayNight::thetaTable[3].x = 0.75;  DayNight::thetaTable[3].y = 3.926991;

  }

  // D38B04: float dnProgression (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;

}