Reads the contents of an ASCII Patran Neutral File, and outputs a group structure containing nodes and connectivity.
module ReadPatranCore <src_file="rd_patrn.cxx",
cxx_src_files = "patran.cxx",
cxx_hdr_files = "patran.hxx",
c_hdr_files = "pneutral.h rnum.h",
c_src_files = "rnum.c",
cxx_members= "load_neutral loadN;"> {
ReadPatranParams+req+IPort2 &ReadPatranParams;
string+req+read+notify filename => <-.ReadPatranParams.filename;
neutral_output+write+OPort2 &neutral_output;
cxxmethod+notify_inst+req update;
};
The low-level ReadPatranCore module takes an input file, in PATRAN neutral file format. The reader is based on the 2.5 specification of Patran. The input stream is parsed, and primitive arrays and scalars are obtained and an output structure is populated. The output structure contains the data necessary to form AVS/Express mesh structures which can be used by other visualization components. Not all entity types present in the PATRAN neutral format are supported. Currently the ReadPatranCore module supports the the following entity types:
Approximate patches are generated from Nurbs and Bspline patches. Patch subdivision has not been implemented and hence these patches are replaced by flat polygons.
&ReadPatranParams
Reference to the parameter block, which contains real instances of the parameters for the ReadPatran modules and macros. The ReadPatranCore module only makes use of the filename parameter. All other parameters are ignored.
filename
The name of the file that should be read from. The parameter is of type string. The filename should specify the full path name of the file. Normally the value of this parameter is found by referring to the parameter block, which is referenced by the &ReadPatranParams input.
neutral_output
A group object containing the structure of the input PATRAN neutral file. The neutral_output group contains a variety of variables. These can be separated into 3 categories:
The Header of the PATRAN neutral file contains two lines of text. These are read into the string variables title1 and title2.
The vertexes contained within the PATRAN file can described by two variables. n_nodes specifies how many nodes the model contains and xyz[n_nodes][3] is an array of coordinates describing the nodes.
The connectivity defining the various entity types is described by a series of pairs of variables. In the case of the triangular mesh, n_tri specifies how many triangles there are in the mesh and tri_conn[n_tri*3] describes which nodes form each of the triangles. If a entity type is not present in the input file then the relevant variables are set to 0. Please note that some of the connectivity variables are currently unused.
The node and connectivity data is used by mesh mapping modules in the ReadPatran functional macro to form mesh data structures that can be used by other visualization components.
The low-level ReadPatranCore module is used in the Functional Macro ReadPatran. This Functional Macro is used within the User Macro read_patran. The low-level ReadPatranCore module also makes use of the ReadPatranParams and neutral_output common parameter blocks.
An example application ReadPatranEg is provided that reads a PATRAN file and renders two views of the data. The first view shows the GroupObject output and can be controlled through the UI. The second view shows how the out_mesh output can be used as the input to visualization modules. The external_edges module is used to reduce the size of the triangle mesh while the shrink_cells module is used to allow the structure of the tetrahedral mesh to be viewed. A sample PATRAN file, ex01.out, is provided with the distribution of this project.
iac_proj/rd_patrn/pat_mods.v contains the V definitions of the ReadPatranCore module and the ReadPatranParams and neutral_output parameter blocks.
If required the number of data packets buffered by the ReadPatranCore module can be changed by editing the patran.hxx file and changing the constants at the top of that file. These are all start with PN_. Comments describe the function of each of these constants.
The low-level ReadPatranMods library containing the module ReadPatranCore does not specify a process. By default the express process will be used.
David Laidlaw, John Stephens, Steve Larkin, Ian Curington Advanced Visual Systems, Ltd. Hanworth Lane, Chertsey Surrey, UK KT16 9JX
Andrew Dodd International AVS Centre
International AVS Centre Manchester Visualization Centre Manchester Computing University of Manchester Oxford Road Manchester United Kingdom M13 9PL
ReadPatran, ReadPatranUI, read_patran, ReadPatranParams, neutral_output, ReadPatranEg, Read UCD, Mesh Mappers