Function DrawVisLightningBolt

Descent3/viseffect.cpp:1182–1258

Draws a lighting bolt from one area to another Velocity.x is how much randomness goes into drawing Velocity.y is the scalar that effects how many segments to draw

// Velocity.x is how much randomness goes into drawing
// Velocity.y is the scalar that effects how many segments to draw
void DrawVisLightningBolt(vis_effect *vis) {
  vector line_norm;
  float line_mag;
  int num_segs;
  float lightning_mag;

  g3Point pnt1, pnt2;

  line_norm = vis->pos - vis->end_pos;
  line_mag = vm_GetMagnitudeFast(&line_norm);

  line_norm /= line_mag;

  if (line_mag < 1)
    return;

  float alpha_norm;

  if (vis->flags & VF_EXPAND) {
    num_segs = line_mag * vis->velocity.y;
    lightning_mag = vis->velocity.x;

    alpha_norm = vis->lifeleft / vis->lifetime;
  } else {
    num_segs = line_mag * vis->velocity.y;
    lightning_mag = vis->velocity.x;

    alpha_norm = .7f;

    // Make it powerup up based on distance
    if (line_mag > 30 && (vis->flags & VF_NO_Z_ADJUST)) {
      float scalar = 1.0 - ((line_mag - 30) / 150.0);
      if (scalar < 0)
        return;

      alpha_norm *= scalar;
    }
  }

  if (num_segs < 2)
    return;

  // Set some states

  rend_SetTextureType(TT_FLAT);
  rend_SetAlphaType(AT_SATURATE_VERTEX);
  rend_SetLighting(LS_NONE);
  rend_SetZBufferWriteMask(0);

  if (vis->id == GRAY_LIGHTNING_BOLT_INDEX) {
    // get the color from the struct
    rend_SetFlatColor(GR_16_TO_COLOR(vis->lighting_color));
  } else {
    rend_SetFlatColor(GR_RGB(10, 60, 200));
  }

  pnt1.p3_a = alpha_norm;
  pnt2.p3_a = alpha_norm;