3 files changed, 94 insertions, 31 deletions

diff --git a/apps/web/src/lib/effects/definitions/blur.frag.glsl b/apps/web/src/lib/effects/definitions/blur.frag.glsl
index 2c015725..c9ad2eae 100644
--- a/apps/web/src/lib/effects/definitions/blur.frag.glsl
+++ b/apps/web/src/lib/effects/definitions/blur.frag.glsl
@@ -3,6 +3,7 @@ precision mediump float;
 uniform sampler2D u_texture;
 uniform vec2 u_resolution;
 uniform float u_sigma;
+uniform float u_step;
 uniform vec2 u_direction;
 
 varying vec2 v_texCoord;
@@ -13,13 +14,12 @@ void main() {
   vec4 color = vec4(0.0);
   float totalWeight = 0.0;
 
-  // step=1 texel — scaling step size instead causes discrete ghosting artifacts
   for (int i = -30; i <= 30; i++) {
-    float fi = float(i);
-    float weight = exp(-(fi * fi) / (2.0 * u_sigma * u_sigma));
-    color += texture2D(u_texture, v_texCoord + texelSize * u_direction * fi) * weight;
+    float pos = float(i) * u_step;
+    float weight = exp(-(pos * pos) / (2.0 * u_sigma * u_sigma));
+    color += texture2D(u_texture, v_texCoord + texelSize * u_direction * pos) * weight;
     totalWeight += weight;
   }
 
   gl_FragColor = color / totalWeight;
-}
+}
\ No newline at end of file
diff --git a/apps/web/src/lib/effects/definitions/blur.ts b/apps/web/src/lib/effects/definitions/blur.ts
index 3819f82c..54934402 100644
--- a/apps/web/src/lib/effects/definitions/blur.ts
+++ b/apps/web/src/lib/effects/definitions/blur.ts
@@ -1,6 +1,72 @@
-import type { EffectDefinition } from "@/types/effects";
+import type { EffectDefinition, ResolvedEffectPass } from "@/lib/effects/types";
 import blurFragmentShader from "./blur.frag.glsl";
 
+const MAX_SINGLE_PASS_SIGMA = 10;
+const MAX_STEP = 4;
+const MAX_EFFECTIVE_SIGMA = MAX_SINGLE_PASS_SIGMA * MAX_STEP;
+const MAX_ITERATIONS = 8;
+
+/**
+ * Builds multi-pass gaussian blur passes for a given sigma.
+ * Shared by the blur effect and background blur — they each
+ * compute their own sigma from their own intensity scale.
+ */
+export function buildGaussianBlurPasses({
+	sigmaX,
+	sigmaY,
+}: {
+	sigmaX: number;
+	sigmaY: number;
+}): ResolvedEffectPass[] {
+	const maxSigma = Math.max(sigmaX, sigmaY);
+	if (maxSigma < 0.001) return [];
+
+	const iterations = Math.min(
+		MAX_ITERATIONS,
+		Math.max(
+			1,
+			Math.ceil(
+				(maxSigma * maxSigma) /
+					(MAX_EFFECTIVE_SIGMA * MAX_EFFECTIVE_SIGMA),
+			),
+		),
+	);
+	const perPassSigmaX = sigmaX / Math.sqrt(iterations);
+	const perPassSigmaY = sigmaY / Math.sqrt(iterations);
+	const stepX = Math.max(1, perPassSigmaX / MAX_SINGLE_PASS_SIGMA);
+	const stepY = Math.max(1, perPassSigmaY / MAX_SINGLE_PASS_SIGMA);
+
+	const passes: ResolvedEffectPass[] = [];
+	for (let i = 0; i < iterations; i++) {
+		passes.push({
+			fragmentShader: blurFragmentShader,
+			uniforms: {
+				u_sigma: perPassSigmaX,
+				u_step: stepX,
+				u_direction: [1, 0],
+			},
+		});
+		passes.push({
+			fragmentShader: blurFragmentShader,
+			uniforms: {
+				u_sigma: perPassSigmaY,
+				u_step: stepY,
+				u_direction: [0, 1],
+			},
+		});
+	}
+	return passes;
+}
+
+function intensityToSigma(intensity: number, resolution: number, reference: number): number {
+	return (intensity / 5) * (resolution / reference);
+}
+
+function parseIntensity(effectParams: Record<string, unknown>): number {
+	const raw = effectParams.intensity;
+	return typeof raw === "number" ? raw : Number.parseFloat(String(raw));
+}
+
 export const blurEffectDefinition: EffectDefinition = {
 	type: "blur",
 	name: "Blur",
@@ -19,32 +85,29 @@ export const blurEffectDefinition: EffectDefinition = {
 	renderer: {
 		type: "webgl",
 		passes: [
-		{
-			fragmentShader: blurFragmentShader,
-			uniforms: ({ effectParams, width }) => {
-				const intensity =
-					typeof effectParams.intensity === "number"
-						? effectParams.intensity
-						: Number.parseFloat(String(effectParams.intensity));
-				return {
-					u_sigma: Math.max((intensity / 5) * (width / 1920), 0.001),
+			{
+				fragmentShader: blurFragmentShader,
+				uniforms: ({ effectParams, width }) => ({
+					u_sigma: Math.max(intensityToSigma(parseIntensity(effectParams), width, 1920), 0.001),
+					u_step: 1,
 					u_direction: [1, 0],
-				};
+				}),
 			},
-		},
-		{
-			fragmentShader: blurFragmentShader,
-			uniforms: ({ effectParams, height }) => {
-				const intensity =
-					typeof effectParams.intensity === "number"
-						? effectParams.intensity
-						: Number.parseFloat(String(effectParams.intensity));
-				return {
-					u_sigma: Math.max((intensity / 5) * (height / 1080), 0.001),
+			{
+				fragmentShader: blurFragmentShader,
+				uniforms: ({ effectParams, height }) => ({
+					u_sigma: Math.max(intensityToSigma(parseIntensity(effectParams), height, 1080), 0.001),
+					u_step: 1,
 					u_direction: [0, 1],
-				};
+				}),
 			},
-		},
 		],
+		buildPasses: ({ effectParams, width, height }) => {
+			const intensity = parseIntensity(effectParams);
+			return buildGaussianBlurPasses({
+				sigmaX: intensityToSigma(intensity, width, 1920),
+				sigmaY: intensityToSigma(intensity, height, 1080),
+			});
+		},
 	},
 };
diff --git a/apps/web/src/lib/effects/definitions/index.ts b/apps/web/src/lib/effects/definitions/index.ts
index 1742b1d7..edc8c5e2 100644
--- a/apps/web/src/lib/effects/definitions/index.ts
+++ b/apps/web/src/lib/effects/definitions/index.ts
@@ -1,13 +1,13 @@
-import { hasEffect, registerEffect } from "../registry";
+import { effectsRegistry } from "../registry";
 import { blurEffectDefinition } from "./blur";
 
 const defaultEffects = [blurEffectDefinition];
 
 export function registerDefaultEffects(): void {
 	for (const definition of defaultEffects) {
-		if (hasEffect({ effectType: definition.type })) {
+		if (effectsRegistry.has(definition.type)) {
 			continue;
 		}
-		registerEffect({ definition });
+		effectsRegistry.register(definition.type, definition);
 	}
 }