const char *wideline_fs =
  "#version 400\n"
  "\n"
  "in vec4 outColor;\n"
  "in float fragLineParam;\n"
  "out vec4 colorOut;\n"
  "\n"
  "void main()\n"
  "{\n"
  "  // Dashed line support: lineParam ranges from 0 to dashCount*2.\n"
  "  // Each period of 2.0 has a dash [0,1) and a gap [1,2).\n"
  "  // For solid lines, lineParam is 0 everywhere (never discarded).\n"
  "  if (fragLineParam > 0.0) {\n"
  "    float phase = mod(fragLineParam, 2.0);\n"
  "    if (phase > 1.0)\n"
  "      discard;\n"
  "  }\n"
  "  colorOut = outColor;\n"
  "}\n"
  "\n";
