Simplygon API 7.1 User guide > Working with transforms

The Simplygon API allows the user to do transformations on geometry data and scene nodes (see section on scenes).

IMatrix4x4

The IMatrix4x4 class is used to represent a standard or homogeneous 4x4 matrix inside the Simplygon API. The matrix is stored in a row major form. The class provides methods for accessing and setting matrix elements, transposing a matrix, calculating an inverse and can be used to transform 3D homogeneous coordinates.

ITransform3

The ITransform3 class is a utility class to setup a 4x4 homogeneous transform in the Simplygon API. You can use the ITransform3 to concatenate transformations. Transforms can be performed by calling AddTranslation, AddRotation and AddScaling. AddRotationworks like a quaternion where you pass in the angle of rotation in radians and set the axis along which to rotate. The PreMultiplyfunction can be use to add a transform around the current transform and PostMultiply can be used to add a transform inside the current transform. The default behaviour is set to do post multiplication.

Transformation Example

void TransformGeometryData(spGeometryData geom)
{
    spTransform3 xform = sg->CreateTransform3();
    // Set the tranfrom to use pre multiply.
    xform->PreMultiply();
    // Do a translations transformation.
    xform->AddTranslation(0,5.0,0.0);

    // ... do other transformations ...
    geom->Transform(xform);

}