From Hand-Drawn to AI: 2D Skeletal Animation Is Undergoing a Silent Revolution

AI Enters the Scene: Animating with Natural Language In recent years, the explosive growth of text-to-image and text-to-video generation has led me to wonder: Can skeletal animation also be described using natural language? My ideal workflow looks like this: 1. Rig the character as usual. 2. Then I say: "This character performs a charged attack—starting from a crouch, leaning backward, pulling the right arm back, then dashing forward rapidly to slash." 3. The AI understands this description and automatically generates all keyframes. 4. I fine-tune minor details and export. This idea sounds simple—but implementation is full of pitfalls. After eight months of development, I built LoongBones—a 2D skeletal animation creation platform powered by AI assistance. Real-world results: 10 seconds vs. 3 hours Using LoongBones, my workflow transformed as follows: Before (fully manual): ・ Rigging: 30 minutes ・ Motion planning: 10 minutes ・ Keyframing: 3 hours ・ Curve refinement: 40 minutes ・ Total: Over 4 hours Now (AI-assisted): ・ Rigging: 30 minutes (unchanged) ・ Describing motion: 10 seconds ・ AI generation: 30 seconds ・ Manual fine-tuning: 20 minutes ・ Total: ~1 hour That’s a 4× efficiency gain. More importantly—revision cost drops nearly to zero. When a designer says, “Make the attack faster,” I simply adjust the speed parameter in the description and get a new version in 10 seconds. Previously, I’d have cursed that request; now I just say, “Sure, one moment.” Relationship with Spine: Enhancement, Not Replacement Many readers may already be using Spine. Rest assured—LoongBones is not meant to replace it.

CGDive’s Rigging Fundamentals Series on YouTube: [6-2/7] Custom Rigging (Practical Session)

Following yesterday’s theoretical lesson, let’s move on today to hands-on practice and reinforcement. First, download the model used for rigging via the link provided at the end of this article. Next, let’s review the chapter outline. I. Model Overview Open the downloaded model: ch6-2_practice_character. This model features: ・ Animal-style leg structure; ・ One standard human arm; ・ One tentacle-like arm—ideal for practicing the spline tentacle technique covered in the previous lesson; ・ A head with ears; ・ A tail. In short, this composite model lets you practice all major preset bone types effectively. Before we begin—have you already decided where to start? You could begin by creating a basic human skeleton preset, since most of the model resembles a humanoid figure. Alternatively, you might start with a quadruped rig, given the animal-style legs—and even the ears. II. Building the Meta-Rig from Scratch Today’s tutorial begins with the head rig. ・ Press [Shift+A] to create a single-segment bone. ・ Switch to Perspective mode. ・ Press [Tab] to enter Edit Mode. ・ In Edit Mode, press [X] to delete this initial bone (like deleting the default cube in a new scene, this placeholder bone is typically removed first). ・ In the Properties panel on the right, under the Rigify menu, go to “Sample Presets,” search for “spine,” locate “spines.basic_spine,” and click “Add Sample.” ・ Align the spine bones to the model. Next, build the leg rigs. Before deciding which leg rig best suits our model, CGDive sets up two distinct leg structures—one aligned to each leg. ・ One uses the human leg preset: limbs.leg. (This gives us two leg rigs; once finalized, we can simply mirror the chosen one.) ・ Align it to the left leg. ・ After alignment, press [H] to hide this left-leg rig. ・ The other uses the animal hind-leg preset: limbs.rear_paw. ・ Align it to the right leg. ・ Press [Alt+H] to unhide the left-leg rig. ・ Roughly align both leg rigs’ positions relative to each other. Next, search for and add arm presets to the scene. ・ Align the arm bones to the model: ensure they form a straight line in Front View, and maintain a natural posterior elbow curve in Top View. ・ For shoulder bones, select the basic.super_copy preset and align it to the shoulder joint. ・ Press [F2] to rename the bone “shoulder.L.” ・ Right-click → “Symmetrize” to mirror it across the body. ・ Continue adding the head preset: search for and insert head/neck presets, then align them accordingly. ・ Next, add the tentacle preset: limbs.spline_tentacle, and align it to the tentacle-like arm. ・ Search for and add the tail preset: spines.basic_tail, then align it to the tail. ・ Press [S] + [Z] + type “0” to flatten the tail bones into a straight line when viewed from the side. ・ To add more vertebrae to the tail: drag the outermost control sphere to lengthen the chain, then right-click → “Subdivide.” ・ Finally, for the ears, use the simple tentacle preset: limbs.simple_tentacle.

Skeletal-editing 'dream' realized

Sep 24, 2026

University of Chicago chemist Mark D. Levin achieved a breakthrough in skeletal editing, enabling versatile carbon-to-nitrogen swaps in complex molecules to aid pharmaceutical lead optimization. Published in Science, this reaction overcomes prior limitations to support drug discovery efforts.

cen

2026-09-24

Skeletal-editing 'dream' realized

Skeletal-editing 'dream' realized

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