Method LoadCamera

IO/Geometry/vtkGLTFDocumentLoaderInternals.cxx:512–607

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//------------------------------------------------------------------------------
bool vtkGLTFDocumentLoaderInternals::LoadCamera(
  const nlohmann::json& root, vtkGLTFDocumentLoader::Camera& camera)
{
  if (root.is_null() || !root.is_object())
  {
    vtkErrorWithObjectMacro(this->Self, "Invalid camera object");
    return false;
  }

  std::string type;
  if (!vtkGLTFUtils::GetStringValue(root, "type", type))
  {
    vtkErrorWithObjectMacro(this->Self, "camera.type field is required but not found");
    return false;
  }
  camera.Name = "";
  vtkGLTFUtils::GetStringValue(root, "name", camera.Name);

  nlohmann::json camRoot; // used to extract zfar and znear, can be either camera.orthographic or
                          // camera.perspective objects.

  if (type == "orthographic")
  {
    camRoot = root.value("orthographic", nlohmann::json::object());
    camera.IsPerspective = false;
  }
  else if (type == "perspective")
  {
    camRoot = root.value("perspective", nlohmann::json::object());
    camera.IsPerspective = true;
  }
  else
  {
    vtkErrorWithObjectMacro(
      this->Self, "Invalid camera.type value. Expecting 'orthographic' or 'perspective'");
    return false;
  }

  if (!vtkGLTFUtils::GetDoubleValue(camRoot, "znear", camera.Znear))
  {
    vtkErrorWithObjectMacro(this->Self, "Invalid camera.znear value.");
    return false;
  }

  // zfar is only required for orthographic cameras
  // znear is required for both types, and has to be positive
  if (!vtkGLTFUtils::GetDoubleValue(camRoot, "zfar", camera.Zfar) && type == "orthographic")
  {
    vtkErrorWithObjectMacro(this->Self, "Invalid camera.zfar value.");
    return false;
  }
  if (camera.Znear <= 0 && type == "orthographic" &&
    (camera.Zfar <= camera.Znear || camera.Zfar <= 0))
  {
    vtkErrorWithObjectMacro(this->Self, "Invalid camera.orthographic znear and zfar values");
    return false;
  }