Panda3D - Todo

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Character

Protein

You can follow the official tutorial here:

https://arsthaumaturgis.github.io/Panda3DTutorial.io/tutorial/tut_lesson01.html

You can model/visualize a protein by:

  1. Loading a structure file (typically PDB or mmCIF)
  2. Parsing atoms/residues
  3. Building a 3D representation (common choices):
  • Ball-and-stick (atoms = spheres, bonds = cylinders)
  • Space-filling / CPK (big spheres, no bonds)
  • Ribbon/cartoon (harder; needs secondary-structure + smooth splines/surfaces)
  1. Rendering it in Panda3D, with interaction (orbit, zoom, pick, etc.)

Below is a practical starting point: atoms as colored spheres from a .pdb file.

Where to go next (depending on what “model” means)

  1. Add bonds (ball-and-stick)

You’ll need to infer bonds (PDB often doesn’t list them). Common approaches:

  • Distance-based bonding by covalent radii thresholds
  • Use CONECT records when present Then render bonds as cylinders oriented between atom pairs.
  1. Cartoon / ribbon (secondary structure)

This is the most “protein-typical” view, but it’s more work:

  • Compute backbone trace (N–CA–C) per residue
  • Smooth the CA path (splines)
  • Build a ribbon mesh along the spline
  • Optional: compute helices/sheets (or read from DSSP)
  1. Performance for large proteins

Thousands of loadModel(“sphere”) calls will get slow. For speed, you’ll want:

  • Instancing (one sphere geometry, many transforms)
  • Or merge into a single Geom (batching)
  • Or impostors / point sprites for atoms when zoomed out

Ball

Ball-and-stick in Panda3D is a great fit: spheres for atoms + cylinders for bonds. The only “gotcha” is that PDB files often don’t include bonds, so you usually infer them from inter-atomic distances (unless CONECT records exist).

Below is a solid starter that:

  • parses ATOM/HETATM
  • centers and scales coordinates
  • draws colored spheres
  • infers bonds by distance using covalent radii
  • draws cylinders oriented between atoms

Identify bonds between atoms. Since PDB files might not always have explicit CONECT records for all bonds (especially for proteins), a common approach is to use a distance-based heuristic.

Render bonds as cylinders connecting the atoms.

References

https://medium.com/@ezrazufarn/how-to-use-panda3d-in-python-to-make-a-3d-environment-and-actor-model-loader-f38d5fa8eb5a