The fun of experimenting with brushes is that you have to start with how the ink behaves.How it spreads, how the vectors flow.Only after that do you move on to texture.And honestly, both parts are challenging in their own way.What I experimented with today was adding something like a magnetic force into the ink.While drawing, it naturally starts to form interesting patterns.The strength and density of those textures mostly come from layering 2D Perlin noise.That part alone is already a lot of fun.

Technical notes:

I use a force map to calculate diffusion vectors, simulating how magnetic powder reacts to force.Three layers of smooth noise at different frequencies create regional variation,controlling strength, scale, and density across the stroke.Five layers of texture noise are stacked from coarse to ultra-fine,with each layer affected by the same regional variation system.Organic noise and flow noise help give it a more liquid, material-like feel.All noise sampling is offset by a stroke seed,so recording and playback stay consistent.

A lot of time goes into things no one ever notices.

That’s just life 🙂

實驗筆刷的樂趣在於，你必須先研究墨水的外型（如何分布，以及向量的擴散），再來，才是墨水的質感填充。而我認為兩者都是很有挑戰性的。今天我實驗的是，將墨水加入一點彷彿加入一點磁力的粉末，在繪製的時候，便會有有趣的紋理。而紋理的上的強度，濃淡分布，更多是透過2維perlin noise 的多層調整而成，這真的很有樂趣。技術補充：

• 使用 forceMap 計算擴散向量，模擬「磁力粉末」的受力分布
• 3 層不同頻率的 smoothNoise（8.0, 3.0, 100.0）生成區域性變化，控制強度（0.5-1.5倍）、大小（0.5-2.0倍）、密度（0.01-2.0倍）
• 5 層紋理噪聲（coarse/mid/fine/ultraFine/smooth）疊加，每層都應用區域性變化
• 有機噪聲和流動噪聲模擬液體質感
• 所有 noise 採樣加入 strokeSeed 偏移，確保錄製/播放一致性

＊時間常常花在無人知曉的地方，這就是人生：）