Function DrawVisSineWave

Descent3/viseffect.cpp:1263–1328

Draws a lighting bolt sine wave from one area to another Velocity.x represents how many increments to take (a scalar) Velocity.y represents how "wide" the arcs are from the center of the line

// Velocity.x represents how many increments to take (a scalar)
// Velocity.y represents how "wide" the arcs are from the center of the line
void DrawVisSineWave(vis_effect *vis) {
  vector line_norm;
  float line_mag;
  matrix mat;
  int num_segs;

  vector from, to, base_from, rvec, uvec;
  g3Point pnt1, pnt2;

  line_norm = vis->pos - vis->end_pos;
  line_mag = vm_GetMagnitudeFast(&line_norm);
  if (line_mag < .1)
    return;

  line_norm /= line_mag;

  float alpha_norm;

  if (vis->flags & VF_EXPAND)
    alpha_norm = vis->lifeleft / vis->lifetime;

  num_segs = vis->velocity.x * line_mag; // /2
  line_norm /= vis->velocity.x;          // *2

  alpha_norm = vis->lifeleft / vis->lifetime;

  vm_VectorToMatrix(&mat, &line_norm, &vis->velocity, NULL);
  rvec = mat.rvec * vis->velocity.y; // /4
  uvec = mat.uvec * vis->velocity.y; // /4

  // Set some states

  rend_SetTextureType(TT_FLAT);
  rend_SetAlphaType(AT_SATURATE_VERTEX);
  rend_SetLighting(LS_NONE);
  rend_SetZBufferWriteMask(0);
  rend_SetFlatColor(GR_RGB(10, 60, 200));
  int cur_sin = (vis - VisEffects) * 5000;

  cur_sin += (FrameCount * 2000);

  base_from = vis->end_pos;
  from = base_from;

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

  for (int i = 0; i < num_segs; i++, base_from += line_norm) {
    to = base_from + line_norm + (FixSin((cur_sin) % 65536) * uvec);
    to += (FixCos((cur_sin) % 65536) * rvec);

    g3_RotatePoint(&pnt1, &from);
    g3_RotatePoint(&pnt2, &to);

    pnt1.p3_flags |= PF_RGBA;
    pnt2.p3_flags |= PF_RGBA;

    g3_DrawSpecialLine(&pnt1, &pnt2);