LodObject Manual

Table of Contents

• About
• Access
• Allocation/Deallocation
• Properties
  • Levels
  • Dynamic Parameter IDs
• Dirty Checksums
• Further Reading

About

A LodObject represents a LOD (level of detail) object generator. This generator creates geometry based on various parameters e.g. camera distance. The LodObject class provides access to the parameters of the dynamically defined levels. It is defined in the lib_lodobject.h header file.

LodObject objects are an instance of Olod.

Access

A LodObject object is a BaseObject and can be accessed like any other object. See BaseObject Manual.

Allocation/Deallocation

LodObject objects are created with the usual tools, see Entity Creation and Destruction Manual (Cinema API).

• LodObject::Alloc(): Creates a new LodObject.
• LodObject::Free(): Deletes the given LodObject.

  // This example creates a new LOD object and adds it to the given BaseDocument.
 
  LodObject* const lodObject = LodObject::Alloc();
  if (lodObject == nullptr)
    return maxon::OutOfMemoryError(MAXON_SOURCE_LOCATION);
 
  lodObject->SetName("New LOD Object"_s);
 
  doc->InsertObject(lodObject, nullptr, nullptr);

Properties

The standard parameters of a LodObject can be obtained and changed with C4DAtom::SetParameter()/ C4DAtom::GetParameter(). The parameter IDs are defined in olod.h.

  // This example checks the current criteria of the given LOD object.
  // If it is "User LOD Level" the current level is set to the maximum level.
 
  // get current criteria
  GeData data;
  lodObject->GetParameter(ConstDescID(DescLevel(LOD_CRITERIA)), data, DESCFLAGS_GET::NONE);
  const Int32 criteria = data.GetInt32();
 
  // check if User LOD Level
  if (criteria == LOD_CRITERIA_MANUAL)
  {
    // get max level
    const Int32 maxLevel = lodObject->GetLevelCount() - 1;
    // set current level to max level
    lodObject->SetParameter(ConstDescID(DescLevel(LOD_CURRENT_LEVEL)), maxLevel, DESCFLAGS_SET::NONE);
  }

Levels

A LodObject object handles multiple levels. The current level is used to define the geometry it should create.

• LodObject::GetLevelCount(): Returns the number of levels.
• LodObject::GetCurrentLevel(): Returns the index of the current level.

  // This example hides the objects of the current level.
 
  // get current level
  const Int32 currentLevel = lodObject->GetCurrentLevel();
 
  // hide current level
 
  DescID showControlID;
  if (!lodObject->GetShowControlDescID(currentLevel, showControlID))
    return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
  lodObject->SetParameter(showControlID, false, DESCFLAGS_SET::NONE);

Dynamic Parameter IDs

Each level contains multiple parameters that configure that level. The DescID for these parameters can be obtained with these functions.

In every mode a level defines various display parameters:

• LodObject::GetShowControlDescID(): Returns the DescID for the display mode.
• LodObject::GetDisplayBFCDescID(): Returns the DescID for the backface culling mode.
• LodObject::GetDisplayTexDescID(): Returns the DescID for the texture mode.
• LodObject::GetDisplayEOGLDescID(): Returns the DescID for the Enhanced OpenGL mode.
• LodObject::GetDisplayStModeDescID(): Returns the DescID for the shading style.
• LodObject::GetDisplayShModeDescID(): Returns the DescID for the shading settings.

The IDs of the shading modes and styles are defined in tdisplay.h.

  // This example configures the display settings for each level.
 
  const Int32 maxLevel = lodObject->GetLevelCount();
 
  for (Int32 level = 0; level < maxLevel; ++level)
  {
    DescID descID;
 
    // enable backface culling
    if (!lodObject->GetDisplayBFCDescID(level, descID))
      return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
    lodObject->SetParameter(descID, true, DESCFLAGS_SET::NONE);
 
    // use "Lines" shading
    if (!lodObject->GetDisplayShModeDescID(level, descID))
      return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
    lodObject->SetParameter(descID, DISPLAYTAG_SDISPLAY_NOSHADING, DESCFLAGS_SET::NONE);
 
    // use "Wireframe" style
    if (!lodObject->GetDisplayStModeDescID(level, descID))
      return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
    lodObject->SetParameter(descID, DISPLAYTAG_WDISPLAY_WIREFRAME, DESCFLAGS_SET::NONE);
  }

In "Manual Groups" mode a list of objects can be accessed:

• LodObject::GetManualModeObjectListDescID(): Returns the DescID of the InExclude list.

  // This example configures the given LodObject to use "Manual Groups".
  // The objects referenced in the "objects" AtomArray are moved under
  // the LodObject and are referenced in each group.
 
  // use "Manual Groups" and a manually defined number of groups
  lodObject->SetParameter(ConstDescID(DescLevel(LOD_MODE)), LOD_MODE_MANUAL_GROUPS, DESCFLAGS_SET::NONE);
  lodObject->SetParameter(ConstDescID(DescLevel(LOD_CRITERIA)), LOD_CRITERIA_MANUAL, DESCFLAGS_SET::NONE);
  lodObject->SetParameter(ConstDescID(DescLevel(LOD_LEVEL_COUNT_DYN)), objectCount, DESCFLAGS_SET::NONE);
 
  // add objects to groups
  for (Int32 level = 0; level < objectCount; ++level)
  {
    // get object
    C4DAtom*    const atom = objects->GetIndex(level);
    BaseObject* const baseObject = static_cast<BaseObject*>(atom);
    if (baseObject == nullptr)
      return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
    // make object a child object of the LOD object
    baseObject->Remove();
    doc->InsertObject(baseObject, lodObject, nullptr);
 
    // insert into "Objects" list of the given level
    DescID listID;
    if (!lodObject->GetManualModeObjectListDescID(level, listID))
      return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
    // create InEx data
    GeData data(CUSTOMDATATYPE_INEXCLUDE_LIST, DEFAULTVALUE);
    InExcludeData* const inExData = data.GetCustomDataTypeWritable<InExcludeData>();
    if (inExData == nullptr)
      return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
    // insert object into list
    inExData->InsertObject(baseObject, 1);
    // set parameter
    lodObject->SetParameter(listID, data, DESCFLAGS_SET::NONE);
  }

In "Simplify" mode these settings are available:

• LodObject::GetSimplifyModeDescID(): Returns the DescID of the "Simplify Mode" parameter.
• LodObject::GetDecimateStrengthDescID(): Returns the DescID of the strength parameter.
• LodObject::GetPerObjectControlDescID(): Returns the DescID of the "Per Object" option.
• LodObject::GetNullDisplayDescID(): Returns the DescID of the null display mode.
• LodObject::GetNullRadiusDescID(): Returns the DescID of the null radius parameter.
• LodObject::GetNullAspectRatioDescID(): Returns the DescID of the null aspect radius parameter.
• LodObject::GetNullOrientationDescID(): Returns the DescID of the null orientation parameter.

The null display mode setting IDs are defined in onull.h.

  // This example configures the given LodObject to use the "Simplify" mode.
  // The first level uses the "Convex Hull" mode, the second the "Null" mode.
 
  // use "Simplify" mode and a manual number of levels
  lodObject->SetParameter(ConstDescID(DescLevel(LOD_MODE)), LOD_MODE_SIMPLIFY, DESCFLAGS_SET::NONE);
  lodObject->SetParameter(ConstDescID(DescLevel(LOD_CRITERIA)), LOD_CRITERIA_MANUAL, DESCFLAGS_SET::NONE);
  lodObject->SetParameter(ConstDescID(DescLevel(LOD_LEVEL_COUNT_DYN)), 2, DESCFLAGS_SET::NONE);
 
  DescID descID;
 
  // first level
 
  // set mode to "Convex Hull"
  if (!lodObject->GetSimplifyModeDescID(0, descID))
    return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
  lodObject->SetParameter(descID, LOD_SIMPLIFY_CONVEXHULL, DESCFLAGS_SET::NONE);
 
  // set "Per Object" to true
  if (!lodObject->GetPerObjectControlDescID(0, descID))
    return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
  lodObject->SetParameter(descID, true, DESCFLAGS_SET::NONE);
 
 
  // second level
 
  // set mode to "Null"
  if (!lodObject->GetSimplifyModeDescID(1, descID))
    return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
  lodObject->SetParameter(descID, LOD_SIMPLIFY_NULL, DESCFLAGS_SET::NONE);
 
  // set "Display" to "Circle"
  if (!lodObject->GetNullDisplayDescID(1, descID))
    return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
 
  lodObject->SetParameter(descID, NULLOBJECT_DISPLAY_CIRCLE, DESCFLAGS_SET::NONE);

Dirty Checksums

The dirty checksum of levels and the cache can be obtained with:

• LodObject::GetLevelDirty(): Returns the checksum for the level switch. Every time the level changes, the counter is increased.
• LodObject::GetCacheDirty(): Returns the checksum for the cache creation. Every time the cache is rebuilt, the counter is increased.

Further Reading

• RangeData Manual
• BaseObject Manual
• DescID Manual