Inkwash, a watercolor sketching app and explanation
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I've made a drawing app based on my physical sketching practice, using fluid sim and some shader tricks to mimic watercolor-style ink washes. Best used on iPad or with a drawing tablet. The linked article shows how the core engine works, with plenty of little interactive demos. It was fun to make, sharing in hopes others find it fun too :)
HN · launched Jun 14, 2026 · 250 upvotes (top 3%) · 1 view
Niche: digital painting and drawing software · 68 launches, 9 in the last 7 days ▲ +80% · Explore this niche →
Category and tags
- Media & entertainment
- Content generation
- B2C
- Not AI
- Hobby / open-source project
Visit website ↗ Source listing ↗
More like this: all 68 launches in digital painting and drawing software →
Could you build this?
Partial Building a standard canvas sketching app is vibe-codeable, but realistic watercolor fluid dynamics requires custom GPU shaders and Navier-Stokes simulation.
What it would actually take: The core architecture is built around WebGL/WebGPU and custom GLSL/WGSL fragment and compute shaders that simulate the 2D Navier-Stokes fluid equations, pigment diffusion, evaporation, and paper fiber absorption. The hard parts are tuning the fluid grid simulation to run smoothly at 60+ FPS on mobile devices like iPads and implementing realistic Kubelka-Munk pigment mixing models. This requires specialized expertise in computer graphics, GPU programming, and numerical fluid physics.
Discussion
20 comments analyzed.
Competitors mentioned: Rebelle, Expressii, GIMP, Inkscape
Concerns raised: Unrealistic vortex patterns compared to actual watercolor dynamics, High GPU usage (50-75%) even when not actively drawing, Lacks vector/editable stroke history to adjust effects after creation
Feature requests: PWA support (installable app on tablets/desktop with manifest and service worker), Replay/export feature to show stroke process and wash spreading, Editable vector format to dial vortices up or down after creation, Design water flow as adjustable field underneath strokes, Pause/play buttons on demo canvases to reduce idle GPU consumption
Competitors
Other products that read as similar to this one : 319 launches clear the similarity bar, closest 8 shown.
Attention rank: #6 of 320 (itself plus its competitors, highest first, normalized so YC and Product Hunt are compared fairly).
Launched 228 days after the earliest competitor.
- Creative Canvas: Draw & Paint · ph · 2026-09-14 · 1 upvotes · similarity 0.59
- Creative Canvas · ph · 2026-09-25 · 1 upvotes · similarity 0.58
- Animated Drawing | Animate Art | Doodle · ph · 2026-09-28 · 1 upvotes · similarity 0.50
- Creative Canvas: Sketch. Paint. Create · ph · 2026-09-17 · 2 upvotes · similarity 0.50
- Mix Painter · ph · 2026-09-23 · 2 upvotes · similarity 0.50
- InkFlow · ph · 2026-09-24 · 3 upvotes · similarity 0.48
- Rindraw · ph · 2026-11-03 · 3 upvotes · similarity 0.48
- DrawInk - Learn To Draw · ph · 2026-10-07 · 1 upvotes · similarity 0.48
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