Getting Started¶

Requirements¶

Python 3.8 or later
An OpenSees model (.tcl file) and its results (.mpco file)

Installation¶

From source¶

git clone https://github.com/user/ops-post.git
cd ops-post
pip install .

Editable install (for development)¶

pip install -e .

This installs all dependencies automatically: h5py, numpy, scipy, pyvista, pyvistaqt, PyQt5.

Same-name convention¶

ops-post expects the TCL model and MPCO results to share a base name:

my_model.tcl      <-- OpenSees model (entry point)
my_model.mpco     <-- analysis results (HDF5)

The .tcl file can source other files (nodes.tcl, elements.tcl, etc.) -- ops-post follows all source commands automatically. If your model uses a multi-file layout with main.tcl as the entry point, rename or create a single-file version with the same base name as the .mpco.

Tip

Use the included merge_tcl.py utility to merge a multi-file model into one: python merge_tcl.py main.tcl my_model.tcl

Running¶

# Just the base name -- finds .tcl and .mpco automatically
ops-post my_model

# Or with any extension -- the base name is extracted
ops-post my_model.mpco
ops-post my_model.tcl

# File dialog (no arguments)
ops-post

What happens¶

ops-post my_model
        |
        v
  Find my_model.tcl ──► Parse TCL ──► Generate my_model.mpco.postdata
        |                                  (local axes, beam profiles,
        |                                   element info)
        v
  Find my_model.mpco ──► Read HDF5 ──► Open 3D viewer
                              |
                              v
                    Read .postdata ──► Local axes, beam profiles

First run: parses the TCL, generates .postdata, opens the viewer.
Subsequent runs: skips parsing (.postdata is up to date), opens directly.
After editing TCL: .postdata is regenerated automatically because the .tcl file is newer.

The .postdata file¶

Generated automatically from your TCL model. Contains:

Section	Content
`*LOCAL_AXES`	Quaternion orientation per element
`*BEAM_PROFILE`	Rectangular cross-section vertices per beam section
`*BEAM_PROFILE_ASSIGNMENT`	Element-to-profile mapping
`*ELEMENT_INFO`	Element type and section name per element

You never need to create or edit this file manually.

Note

The .mpco file can be large (50-500 MB for typical models). ops-post uses lazy step loading and a persistent HDF5 handle, so only one time step is in memory at a time.

First steps¶

Run ops-post my_model -- the viewer opens with the default view.
Use right-click drag to rotate, middle-click drag to pan, scroll to zoom.
Select a result category (Nodal / Element) and component from the right panel.
Use the time step slider or Play button to animate.

See Controls & Display for the full reference.