Hermes
dd2a1734eb
- Shelf tool to open/close command port in Houdini - hhb client script (eval, script, get-selected, set-param, etc.) - Hermes skill with standard hou module workflows - Example: create pyro setup - hou module quick reference
114 lines
3.0 KiB
Markdown
114 lines
3.0 KiB
Markdown
# Hermes Skill: Houdini Bridge
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Standard workflows to control a running Houdini session via the hermes-houdini-bridge.
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## Trigger
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When the user asks to:
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- Modify node parameters in Houdini
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- Build node setups/networks in Houdini
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- Write VEX/Wrangle code in Houdini
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- Query selected nodes, connections, or scene state
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- Execute Python in a running Houdini session
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## Prerequisites
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1. User must have the Hermes Bridge shelf tool active in Houdini (port 12345 open)
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2. SSH access to the Houdini workstation (default: `niklas@192.168.178.39`)
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If the bridge is not open, tell the user: "Open the Hermes Bridge shelf tool in Houdini first."
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## Client Location
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`/opt/data/projects/hermes-houdini-bridge/hermes/bin/hhb`
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Always use this full path — the script handles SSH and hcommand internally.
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## Common Workflows
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### 1. Query Selected Nodes
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```bash
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/opt/data/projects/hermes-houdini-bridge/hermes/bin/hhb get-selected
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```
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### 2. Set a Parameter
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```bash
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/opt/data/projects/hermes-houdini-bridge/hermes/bin/hhb set-param <parm_name> <value>
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```
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Example: `hhb set-param file /path/to/texture.exr`
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### 3. Get a Parameter Value
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```bash
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/opt/data/projects/hermes-houdini-bridge/hermes/bin/hhb get-param <parm_name>
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```
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### 4. Execute Arbitrary Python
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```bash
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/opt/data/projects/hermes-houdini-bridge/hermes/bin/hhb eval "<python_code>"
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```
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The code runs in Houdini's Python environment with full `hou` module access.
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### 5. Check Connection
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```bash
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/opt/data/projects/hermes-houdini-bridge/hermes/bin/hhb status
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```
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## Useful hou Module Patterns
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### VEX in a Wrangler
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```python
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node = hou.selectedNodes()[0]
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node.parm('snippet').set('@P.y += sin(@Frame * 0.1);\n@Cd = rand(@ptnum);')
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```
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### Build a Node Chain
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```python
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obj = hou.node('/obj')
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geo = obj.createNode('geo', 'my_setup')
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null_in = geo.createNode('null', 'IN')
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wrangle = geo.createNode('attribwrangle', 'compute')
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null_out = geo.createNode('null', 'OUT')
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wrangle.setInput(0, null_in)
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null_out.setInput(0, wrangle)
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wrangle.parm('snippet').set('@Cd = rand(@ptnum);')
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wrangle.moveToGoodPosition()
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null_out.moveToGoodPosition()
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```
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### Read Node Info
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```python
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n = hou.selectedNodes()[0]
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info = {
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'path': n.path(),
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'type': n.type().name(),
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'parms': {p.name(): p.eval() for p in n.parms() if not p.isAtDefault()},
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'inputs': [c.inputNode().path() for c in n.inputConnections()],
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'outputs': [c.outputNode().path() for c in n.outputConnections()],
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}
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print(info)
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```
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### Create a Material
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```python
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matnet = hou.node('/mat')
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principled = matnet.createNode('principledshader::2.0', 'my_material')
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principled.parm('basecolorr').set(1.0)
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principled.parm('basecolorg').set(0.2)
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principled.parm('basecolorb').set(0.1)
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principled.parm('rough').set(0.3)
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```
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## Pitfalls
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- Complex Python with quotes/backticks: Use `hhb script file.py` instead of `hhb eval "..."`
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- Parameter names are internal (e.g., `file`, not `File`)
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- Node types: check with `node.type().name()` first
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- hcommand timeouts: complex scripts may take time, especially if triggering cooks
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- Selected node counts: always check `len(hou.selectedNodes())` before operating
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