Function DrawVisThickLightning

Descent3/viseffect.cpp:1376–1458

Draws a thick lighting bolt from one area to another Velocity.x is how many times to saturate Velocity.y is how fast the lightning moves across the v component Velocity.z is how many times the effect is tiled across the v component If Billboard_info.texture is not zero, it does autotiling

// Velocity.z is how many times the effect is tiled across the v component
// If Billboard_info.texture is not zero, it does autotiling
void DrawVisThickLightning(vis_effect *vis) {
  // compute the corners of a rod.  fills in vertbuf.
  g3Point top_point, bot_point;
  g3Point pnts[4], *pntlist[4];

  g3_RotatePoint(&top_point, &vis->pos);
  g3_RotatePoint(&bot_point, &vis->end_pos);

  if (!GetBillboardCorners(pnts, &top_point, &bot_point, vis->billboard_info.width))
    return;

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

  line_norm /= line_mag;

  if (line_mag < 1)
    return;

  int texnum = vis->custom_handle;
  int bm_handle = GetTextureBitmap(texnum, 0, true);
  float tile_factor = vis->velocity.z;
  float alpha_norm;
  int i, codes_and;

  if (vis->flags & VF_EXPAND)
    alpha_norm = vis->lifeleft / vis->lifetime;
  else
    alpha_norm = .7f;

  rend_SetOverlayType(OT_NONE);
  rend_SetTextureType(TT_LINEAR);
  rend_SetLighting(LS_FLAT_GOURAUD);
  rend_SetAlphaType(AT_SATURATE_TEXTURE);
  rend_SetWrapType(WT_WRAP);
  rend_SetFlatColor(GR_16_TO_COLOR(vis->lighting_color));
  rend_SetAlphaValue(255 * alpha_norm);
  rend_SetZBufferWriteMask(0);

  for (i = 0, codes_and = 0xff; i < 4; i++) {
    pntlist[i] = &pnts[i];
  }

  if (vis->billboard_info.texture) // do autotiling
  {
    float ratio = line_mag / (float)vis->billboard_info.width;
    tile_factor *= ratio;
  }

  pnts[0].p3_u = 0;
  pnts[0].p3_v = 0;

  pnts[1].p3_u = 1;
  pnts[1].p3_v = 0;

  pnts[2].p3_u = 1;
  pnts[2].p3_v = tile_factor;