Object Gpencil Modifier Add

Object_GpencilModifierAdd slaps a modifier onto a grease pencil object - the pack's node for Blender's bpy.ops.object.gpencil_modifier_add. Where the base Object_GpencilAdd node gives you a blank drawing canvas, this node gives that canvas its behavior: an outline modifier that traces your avatar's mesh, a build modifier that draws strokes in over time, a noise modifier that makes them wobble like real hand drawing. If you're doing any grease-pencil work in the Avatar Graph pack, this is the node you'll spend the most time in.

The modifier menu, decoded

The single input that matters is type, and it's a 26-entry enum. Here's the landscape in plain terms:

• GP_LINEART - the crowd favorite. Generates line art strokes from the edges of mesh geometry, which is how you get a cartoon outline around your avatar.
• GP_BUILD - draws strokes in progressively over time. The classic "sketch draws itself" effect.
• GP_ARRAY, GP_MIRROR, GP_SUBDIV - duplication, mirroring, and smoothing, mirroring their mesh-modifier cousins.
• GP_NOISE - adds jitter to strokes for a hand-drawn, imperfect feel.
• GP_OUTLINE - wraps strokes in a border, good for cel-style pop.
• GP_THICK, GP_LENGTH, GP_SMOOTH, GP_SIMPLIFY - thickness, length, and smoothing refinements.
• GP_TIME - time-based trimming of which parts of a stroke show.
• GP_HOOK, GP_ARMATURE, GP_LATTICE - deformation modifiers that bend strokes with bones or lattices.
• The rest - GP_TEXTURE, GP_DASH, GP_ENVELOPE, GP_WEIGHT_ANGLE, GP_WEIGHT_PROXIMITY, GP_MULTIPLY, GP_COLOR, GP_OPACITY, GP_TINT, SHRINKWRAP - are finer color/weight/effect tools.

How it works

Like every object-level node here, it's an auto-generated wrapper over the matching bpy.ops.object.gpencil_modifier_add operator. It makes your BPY_OBJ active, adds the chosen modifier, and passes the object back through. Two things to keep in mind. First, modifiers stack in order, and the stack order changes the result - an outline added after a noise modifier behaves differently than one added before. Second, each call adds one modifier, so to build a layered stack you chain multiple Object_GpencilModifierAdd nodes in sequence.

Inputs and outputs

• BPY_OBJ (optional) - the grease pencil object to modify.
• type - which modifier to add (26 choices).

Output: BPY_OBJ, the same object, with the modifier appended to its stack. The node doesn't name the modifier for you - you'll typically pick a name later via the string-input modifier nodes like Object_GpencilModifierCopy or Object_GpencilModifierRemove, which address modifiers by name.

Install and gotchas

Standard pack install - ComfyUI Manager (search "Avatar Graph") or:

cd ComfyUI/custom_nodes
git clone https://github.com/avatechai/avatar-graph-comfyui.git
cd avatar-graph-comfyui && python -m pip install -r requirements.txt

Python 3.10 for bpy==3.6.0, ~2.5GB SAM checkpoint + mediapipe models on first load, scene resets each run, and --enable-cors-header for live preview.

The one thing people stumble on: modifiers need a grease pencil object to attach to, and they don't do much until that object has actual strokes. Object_GpencilAdd first, then strokes, then modifiers - that's the order.