🎉

client/src/BrushGenerator.js

@@ -0,0 +1,61 @@
+import * as PIXI from 'pixi.js';
+
+const fragment = `
+uniform float size;
+uniform float erase;
+uniform vec3 color;
+uniform float smoothing;
+
+void main(){
+	vec2 uv = vec2(gl_FragCoord.xy) / size;
+	float dst = distance(uv, vec2(0.5, 0.5)) * 2.;
+	float alpha = max(0., 1. - dst);
+	alpha = pow(alpha, smoothing);
+	if(erase == 0.)
+		gl_FragColor = vec4(color, 1) * alpha;
+	else
+		gl_FragColor = vec4(alpha);
+}
+`;
+
+export default class BrushGenerator {
+	constructor(renderer) {
+		this.renderer = renderer;
+
+		this.filter = new PIXI.Filter(null, fragment, {
+			color: [0, 0, 0],
+			size: 16,
+			erase: 0,
+			smoothing: 0.01
+		});
+	}
+
+	get(size, color, smoothing) {
+		this.filter.uniforms.size = size;
+		this.filter.uniforms.color = color;
+		this.filter.uniforms.smoothing = smoothing;
+
+		const texture = PIXI.RenderTexture.create({width: size, height: size});
+		texture.baseTexture.premultipliedAlpha = true;
+		const sprite = new PIXI.Sprite();
+		sprite.width = size;
+		sprite.height = size;
+
+		sprite.filters = [this.filter];
+		
+		this.renderer.render(sprite, {
+			renderTexture: texture,
+			clear: false,
+		});
+
+		return texture;
+	}
+
+	hexToArray(color) {
+		const r = color >> 16;
+		const g = (color & 0x00ffff) >> 8;
+		const b = color & 0x0000ff;
+
+		return [r / 255, g / 255, b / 255];
+	}
+}