feat: pan & zoom motion presets

Ken Burns-style motion effects (zoom in/out, pan left/right/up/down) that
drag onto clips like regular effects. Instead of shader passes they
evaluate a per-frame transform offset in resolveVisualState, so they
stack with keyframed transforms and work in preview and export.

- intensity param (0-100%, keyframable) scales the whole effect
- easing select maps progress through the graph editor's bezier presets
- supportsStandalone: false hides them from effect-track creation
- empty shader pass groups are filtered out so pass-less effects and
  zero-intensity blur no longer crash the compositor

1 files changed, 132 insertions, 0 deletions

diff --git a/apps/web/src/effects/definitions/motion.ts b/apps/web/src/effects/definitions/motion.ts
new file mode 100644
index 00000000..8c81d801
--- /dev/null
+++ b/apps/web/src/effects/definitions/motion.ts
@@ -0,0 +1,132 @@
+import type { ParamDefinition, ParamValues } from "@/params";
+import type { EffectDefinition, MotionOffset } from "@/effects/types";
+import { MOTION_EASING_OPTIONS, getMotionIntensity } from "@/effects/motion";
+
+const ZOOM_RANGE = 0.35;
+const PAN_ZOOM_HEADROOM = 0.15;
+const PAN_TRAVEL = 0.06;
+
+function motionParams(): ParamDefinition[] {
+	return [
+		{
+			key: "intensity",
+			label: "Intensity",
+			type: "number",
+			default: 100,
+			min: 0,
+			max: 100,
+			step: 1,
+			keyframable: true,
+		},
+		{
+			key: "easing",
+			label: "Easing",
+			type: "select",
+			default: "smooth",
+			options: MOTION_EASING_OPTIONS,
+		},
+	];
+}
+
+function zoomOffset({
+	effectParams,
+	progress,
+	direction,
+}: {
+	effectParams: ParamValues;
+	progress: number;
+	direction: 1 | -1;
+}): MotionOffset {
+	const intensity = getMotionIntensity({ effectParams });
+	const amount =
+		direction === 1 ? progress * intensity : (1 - progress) * intensity;
+	return {
+		scale: 1 + ZOOM_RANGE * amount,
+		translateX: 0,
+		translateY: 0,
+	};
+}
+
+function panOffset({
+	effectParams,
+	progress,
+	axis,
+	direction,
+}: {
+	effectParams: ParamValues;
+	progress: number;
+	axis: "x" | "y";
+	direction: 1 | -1;
+}): MotionOffset {
+	const intensity = getMotionIntensity({ effectParams });
+	const travel = (progress - 0.5) * 2 * PAN_TRAVEL * intensity * direction;
+	return {
+		scale: 1 + PAN_ZOOM_HEADROOM * intensity,
+		translateX: axis === "x" ? travel : 0,
+		translateY: axis === "y" ? travel : 0,
+	};
+}
+
+function buildMotionDefinition({
+	type,
+	name,
+	keywords,
+	evaluate,
+}: Pick<EffectDefinition, "type" | "name" | "keywords"> & {
+	evaluate: NonNullable<EffectDefinition["motion"]>["evaluate"];
+}): EffectDefinition {
+	return {
+		type,
+		name,
+		keywords,
+		params: motionParams(),
+		renderer: { passes: [] },
+		motion: { evaluate },
+		supportsStandalone: false,
+	};
+}
+
+export const motionEffectDefinitions: EffectDefinition[] = [
+	buildMotionDefinition({
+		type: "zoom-in",
+		name: "Zoom In",
+		keywords: ["zoom", "ken burns", "scale", "push in"],
+		evaluate: ({ effectParams, progress }) =>
+			zoomOffset({ effectParams, progress, direction: 1 }),
+	}),
+	buildMotionDefinition({
+		type: "zoom-out",
+		name: "Zoom Out",
+		keywords: ["zoom", "ken burns", "scale", "pull out"],
+		evaluate: ({ effectParams, progress }) =>
+			zoomOffset({ effectParams, progress, direction: -1 }),
+	}),
+	buildMotionDefinition({
+		type: "pan-left",
+		name: "Pan Left",
+		keywords: ["pan", "ken burns", "slide", "left"],
+		evaluate: ({ effectParams, progress }) =>
+			panOffset({ effectParams, progress, axis: "x", direction: -1 }),
+	}),
+	buildMotionDefinition({
+		type: "pan-right",
+		name: "Pan Right",
+		keywords: ["pan", "ken burns", "slide", "right"],
+		evaluate: ({ effectParams, progress }) =>
+			panOffset({ effectParams, progress, axis: "x", direction: 1 }),
+	}),
+	buildMotionDefinition({
+		type: "pan-up",
+		name: "Pan Up",
+		keywords: ["pan", "ken burns", "slide", "up", "tilt"],
+		evaluate: ({ effectParams, progress }) =>
+			panOffset({ effectParams, progress, axis: "y", direction: -1 }),
+	}),
+	buildMotionDefinition({
+		type: "pan-down",
+		name: "Pan Down",
+		keywords: ["pan", "ken burns", "slide", "down", "tilt"],
+		evaluate: ({ effectParams, progress }) =>
+			panOffset({ effectParams, progress, axis: "y", direction: 1 }),
+	}),
+];