function Create3DAnnotation($doc, $annots)
{
// ---------------------------------------------------------------------------------
// Create a 3D annotation based on U3D content. PDF 1.6 introduces the capability
// for collections of three-dimensional objects, such as those used by CAD software,
// to be embedded in PDF files.
$link_3D = $doc->CreateIndirectDict();
$link_3D->PutName("Subtype", "3D");
// Annotation location on the page
$link_3D_rect = new Rect(25.0, 180.0, 585.0, 643.0);
$link_3D->PutRect("Rect", $link_3D_rect->x1, $link_3D_rect->y1, $link_3D_rect->x2, $link_3D_rect->y2);
$annots->PushBack($link_3D);
// The 3DA entry is an activation dictionary (see Table 9.34 in the PDF Reference Manual)
// that determines how the state of the annotation and its associated artwork can change.
$activation_dict_3D = $link_3D->PutDict("3DA");
// Set the annotation so that it is activated as soon as the page containing the
// annotation is opened. Other options are: PV (page view) and XA (explicit) activation.
$activation_dict_3D->PutName("A", "PO");
// Embed U3D Streams (3D Model/Artwork).
global $input_path;
$u3d_file = new MappedFile($input_path . "dice.u3d");
$u3d_reader = new FilterReader($u3d_file);
// To embed 3D stream without compression, you can omit the second parameter in CreateIndirectStream.
$u3d_data_dict = $doc->CreateIndirectStream($u3d_reader, new FlateEncode(new Filter()));
$u3d_data_dict->PutName("Subtype", "U3D");
$link_3D->Put("3DD", $u3d_data_dict);
// Set the initial view of the 3D artwork that should be used when the annotation is activated.
$view3D_dict = $link_3D->PutDict("3DV");
$view3D_dict->PutString("IN", "Unnamed");
$view3D_dict->PutString("XN", "Default");
$view3D_dict->PutName("MS", "M");
$view3D_dict->PutNumber("CO", 27.5);
// A 12-element 3D transformation matrix that specifies a position and orientation
// of the camera in world coordinates.
$tr3d = $view3D_dict->PutArray("C2W");
$tr3d->PushBackNumber(1);
$tr3d->PushBackNumber(0);
$tr3d->PushBackNumber(0);
$tr3d->PushBackNumber(0);
$tr3d->PushBackNumber(0);
$tr3d->PushBackNumber(-1);
$tr3d->PushBackNumber(0);
$tr3d->PushBackNumber(1);
$tr3d->PushBackNumber(0);
$tr3d->PushBackNumber(0);
$tr3d->PushBackNumber(-27.5);
$tr3d->PushBackNumber(0);
// Create annotation appearance stream, a thumbnail which is used during printing or
// in PDF processors that do not understand 3D data.
$ap_dict = $link_3D->PutDict("AP");
$builder = new ElementBuilder();
$writer = new ElementWriter();
$writer->Begin($doc->GetSDFDoc());
$thumb_pathname = $input_path . "dice.jpg";
$image = Image::Create($doc->GetSDFDoc(), $thumb_pathname);
$writer->WritePlacedElement($builder->CreateImage($image, 0.0, 0.0, $link_3D_rect->Width(), $link_3D_rect->Height()));
$normal_ap_stream = $writer->End();
$normal_ap_stream->PutName("Subtype", "Form");
$normal_ap_stream->PutRect("BBox", 0, 0, $link_3D_rect->Width(), $link_3D_rect->Height());
$ap_dict->Put("N", $normal_ap_stream);
}
