About

InstanceObject represents an instance object in Cinema 4D. Such an instance object references another scene object. Additionally, it can store multiple matrices for multi-instances.

InstanceObject objects are an instance of Oinstance.

Creation

InstanceObject objects are created with the usual tools (Entity Creation and Destruction Manual (Classic)):

Properties

The parameters of an InstanceObject are edited as usual using C4DAtom::GetParameter() and C4DAtom::SetParameter(). The parameter IDs are defined in Oinstance.h.

The referenced object can be accessed with the INSTANCEOBJECT_LINK parameter or with these functions:

Multi-Instances

An InstanceObject can store multiple instance positions. So it can represent not only one but many instances. To turn on the multi-instance mode set the parameter INSTANCEOBJECT_RENDERINSTANCE_MODE to INSTANCEOBJECT_RENDERINSTANCE_MODE_MULTIINSTANCE.

// This example creates an intance object that uses the given reference object and matrix object.
// create instance object
if (instance == nullptr)
return maxon::OutOfMemoryError(MAXON_SOURCE_LOCATION);
// insert object into the scene
doc->InsertObject(instance, nullptr, nullptr);
// use the given reference object
instance->SetReferenceObject(reference) iferr_return;
// use position data provided by the given matrix object
return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);
return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);

For each multi-instance a matrix and a color (maxon::Color64) is stored:

// This example defines positions and colors and stores them in the given instance object as multi-instance data.
// prepare matrices and colors
const Int count = 100;
matrices.Resize(count) iferr_return;
colors.Resize(count) iferr_return;
// generate positions and colors
Float position = 0.0;
const Float step = 300.0;
Float hue = 0.0;
const Float hueStep = 1.0 / count;
for (Int i = 0; i < count; ++i)
{
// matrices
matrices[i] = MatrixMove(Vector(position, 0.0, 0.0));
position += step;
// colors
const Vector colorHSV = Vector(hue, 1.0, 1.0);
const Vector colorRGB = HSVToRGB(colorHSV);
colors[i] = maxon::Color64(colorRGB);
hue += hueStep;
}
// store data in the instance object
instance->SetInstanceMatrices(matrices) iferr_return;
instance->SetInstanceColors(colors) iferr_return;

The multi-instance information can also be accessed with a MultiInstanceData object:

// This example reads the multi-instance data from the given instance object using MultiInstanceData.
// read data
data.ExtractInfo(instanceObject) iferr_return;
// for each position, create a cube object
for (const Matrix& mg : data.instanceMatrices)
{
if (cube == nullptr)
return maxon::OutOfMemoryError(MAXON_SOURCE_LOCATION);
cube->SetMg(mg);
doc->InsertObject(cube, nullptr, nullptr);
}

Further Reading