td-api-reference

TouchDesigner Python API Reference

Verify unfamiliar TD behavior before asserting it: get_docs('<Operator or Class>') reads the offline help mirror first, the wiki (https://docs.derivative.ca: OP Class, COMP Class, Par Class, Extensions, Cook) second, and describe_op_type gives an operator type's real parameter names. Assumptions about TD's Python API are frequently wrong. Two companions in this skill's folder hold the long tail: references/background-work.md (the Web Client DAT and Thread Manager code) and references/heavy-build-safety.md (crash causes and caps). Read them before any fetch, thread or heavy build; without a skills folder, get_guidance(topic='td-api-reference/background-work').

Parameter Access Patterns

value = op('geo1').par.tx.eval()   # CORRECT: the current runtime value
value = op('geo1').par.tx.val      # WRONG: constant-mode value only
op('geo1').par.tx = 5              # set; .val = 5 also silently switches the mode to CONSTANT
op('geo1').par.xord = 'trs'        # menus take the name or the index
me.par.tx.eval().hex()             # cast AFTER eval(); me.par.tx.hex() is wrong

Creating Custom Parameters

All append* methods return a ParGroup (tuple-like), never a single Par: index with [0].

page = comp.appendCustomPage('Controls')
p = page.appendFloat('Speed', label='Speed')[0]
p.default = 0.5; p.val = p.default          # .default never sets the value
p.normMin = 0; p.normMax = 2                # slider range
p.min = 0; p.clampMin = True                # hard clamp
p.help = "Playback speed multiplier."       # ALWAYS set help
p.startSection = True                       # separator above
# appendInt / appendToggle / appendStr / appendMenu (EMPTY menu: set .menuNames/.menuLabels)
# appendPulse / appendRGB ('Color' -> Colorr/g/b) / appendXYZ ('Pos' -> Pos1/2/3) / appendOP / appendFile

Names start uppercase, then lowercase letters and digits, no underscores. Get-or-create (never a blind append*), callbacks, styles, ranges, help text: /parameter-design. Docs: https://docs.derivative.ca/Custom_Parameters