1 files changed, 110 insertions, 0 deletions
diff --git a/apps/web/src/effects/definitions/blur.ts b/apps/web/src/effects/definitions/blur.ts
new file mode 100644
index 00000000..194196e9
--- /dev/null
+++ b/apps/web/src/effects/definitions/blur.ts
@@ -0,0 +1,110 @@
+import type { EffectDefinition, EffectPass } from "@/effects/types";
+
+export const GAUSSIAN_BLUR_SHADER = "gaussian-blur";
+
+const MAX_SINGLE_PASS_SIGMA = 10;
+const MAX_STEP = 4;
+const MAX_EFFECTIVE_SIGMA = MAX_SINGLE_PASS_SIGMA * MAX_STEP;
+const MAX_ITERATIONS = 8;
+
+export function buildGaussianBlurPasses({
+	sigmaX,
+	sigmaY,
+}: {
+	sigmaX: number;
+	sigmaY: number;
+}): EffectPass[] {
+	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: EffectPass[] = [];
+	for (let i = 0; i < iterations; i++) {
+		passes.push({
+			shader: GAUSSIAN_BLUR_SHADER,
+			uniforms: {
+				u_sigma: perPassSigmaX,
+				u_step: stepX,
+				u_direction: [1, 0],
+			},
+		});
+		passes.push({
+			shader: GAUSSIAN_BLUR_SHADER,
+			uniforms: {
+				u_sigma: perPassSigmaY,
+				u_step: stepY,
+				u_direction: [0, 1],
+			},
+		});
+	}
+	return passes;
+}
+
+export const INTENSITY_TO_SIGMA_DIVISOR = 5;
+
+export function intensityToSigma({ intensity, resolution, reference }: { intensity: number; resolution: number; reference: number }): number {
+	return (intensity / INTENSITY_TO_SIGMA_DIVISOR) * (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",
+	keywords: ["blur", "soft", "defocus"],
+	params: [
+		{
+			key: "intensity",
+			label: "Intensity",
+			type: "number",
+			default: 15,
+			min: 0,
+			max: 100,
+			step: 1,
+		},
+	],
+	renderer: {
+		passes: [
+			{
+				shader: GAUSSIAN_BLUR_SHADER,
+				uniforms: ({ effectParams, width }) => ({
+					u_sigma: Math.max(intensityToSigma({ intensity: parseIntensity(effectParams), resolution: width, reference: 1920 }), 0.001),
+					u_step: 1,
+					u_direction: [1, 0],
+				}),
+			},
+			{
+				shader: GAUSSIAN_BLUR_SHADER,
+				uniforms: ({ effectParams, height }) => ({
+					u_sigma: Math.max(intensityToSigma({ intensity: parseIntensity(effectParams), resolution: height, reference: 1080 }), 0.001),
+					u_step: 1,
+					u_direction: [0, 1],
+				}),
+			},
+		],
+		buildPasses: ({ effectParams, width, height }) => {
+			const intensity = parseIntensity(effectParams);
+		return buildGaussianBlurPasses({
+				sigmaX: intensityToSigma({ intensity, resolution: width, reference: 1920 }),
+				sigmaY: intensityToSigma({ intensity, resolution: height, reference: 1080 }),
+			});
+		},
+	},
+};