alignment brush

labs/folk-brush-field.ts

@@ -0,0 +1,527 @@
+import { Gizmos, Point, Vector } from '@lib';
+import { FolkBaseSet } from './folk-base-set';
+import { FolkShape } from './folk-shape';
+
+interface AlignmentLine {
+  shapes: Set<FolkShape>;
+  points: Map<FolkShape, Point>;
+  lineStart: Point;
+  lineEnd: Point;
+  isHorizontal: boolean;
+}
+
+export class FolkBrushField extends FolkBaseSet {
+  static override tagName = 'folk-brush-field';
+
+  // Core structure
+  #alignments = new Set<AlignmentLine>();
+  #shapeToAlignments = new Map<FolkShape, Set<AlignmentLine>>();
+
+  // Interaction state
+  #isPointerDown = false;
+  #lastPointerPosition: Point | null = null;
+  #selectedShapes = new Set<FolkShape>();
+
+  // Canvas for brush visualization
+  #canvas!: HTMLCanvasElement;
+  #ctx!: CanvasRenderingContext2D;
+
+  // Brush settings
+  readonly #BRUSH_RADIUS = 60;
+  readonly #TARGET_PADDING = 20;
+
+  // Add new constants for removal threshold
+  readonly #REMOVAL_THRESHOLD_MULTIPLIER = 1.0; // Multiplied by shape size
+
+  // Add property to track dragging state
+  #draggedShape: FolkShape | null = null;
+
+  connectedCallback() {
+    super.connectedCallback();
+    this.#setupCanvas();
+    this.#setupEventListeners();
+    requestAnimationFrame(this.#updateCanvas);
+  }
+
+  disconnectedCallback() {
+    super.disconnectedCallback();
+    window.removeEventListener('resize', this.#handleResize);
+  }
+
+  #setupCanvas() {
+    this.#canvas = document.createElement('canvas');
+    this.#canvas.style.cssText = `
+      position: absolute;
+      top: 0;
+      left: 0;
+      width: 100%;
+      height: 100%;
+      pointer-events: none;
+    `;
+    const ctx = this.#canvas.getContext('2d');
+    if (!ctx) throw new Error('Could not get canvas context');
+    this.#ctx = ctx;
+    this.renderRoot.prepend(this.#canvas);
+    this.#handleResize();
+  }
+
+  #setupEventListeners() {
+    this.addEventListener('pointerdown', this.#handlePointerDown);
+    this.addEventListener('pointermove', this.#handlePointerMove);
+    this.addEventListener('pointerup', this.#handlePointerUp);
+    this.addEventListener('pointerleave', this.#handlePointerUp);
+    window.addEventListener('resize', this.#handleResize);
+    this.addEventListener('pointerdown', this.#handleShapePointerDown, true);
+    this.addEventListener('pointerup', this.#handleShapePointerUp, true);
+  }
+
+  #handleResize = () => {
+    const { width, height } = this.getBoundingClientRect();
+    this.#canvas.width = width;
+    this.#canvas.height = height;
+  };
+
+  #handlePointerDown = (event: PointerEvent) => {
+    if (event.button !== 0) return;
+    if (event.target !== this) return;
+
+    const rect = this.#canvas.getBoundingClientRect();
+    const point = {
+      x: event.clientX - rect.left,
+      y: event.clientY - rect.top,
+    };
+
+    this.#selectedShapes.clear();
+    this.#isPointerDown = true;
+    this.#lastPointerPosition = point;
+
+    // Find shapes under initial point
+    this.sourceElements.forEach((element) => {
+      if (element instanceof FolkShape) {
+        const rect = element.getTransformDOMRect();
+        if (
+          point.x >= rect.x &&
+          point.x <= rect.x + rect.width &&
+          point.y >= rect.y &&
+          point.y <= rect.y + rect.height
+        ) {
+          this.#selectedShapes.add(element);
+        }
+      }
+    });
+  };
+
+  #handlePointerMove = (event: PointerEvent) => {
+    if (!this.#isPointerDown || !this.#lastPointerPosition) return;
+
+    const rect = this.#canvas.getBoundingClientRect();
+    const point = {
+      x: event.clientX - rect.left,
+      y: event.clientY - rect.top,
+    };
+
+    // Check for shapes under the new line segment
+    this.sourceElements.forEach((element) => {
+      if (element instanceof FolkShape) {
+        const shapeRect = element.getTransformDOMRect();
+        if (this.#isLineIntersectingRect(this.#lastPointerPosition!, point, shapeRect)) {
+          this.#selectedShapes.add(element);
+        }
+      }
+    });
+
+    this.#drawBrushStroke(this.#lastPointerPosition, point);
+    this.#lastPointerPosition = point;
+  };
+
+  #handlePointerUp = () => {
+    if (this.#selectedShapes.size >= 2) {
+      // Find existing alignments that overlap with selected shapes
+      const overlappingAlignments = new Set<AlignmentLine>();
+      const isHorizontal = this.#determineAlignment(this.#selectedShapes);
+
+      // Find all overlapping alignments with the same orientation
+      for (const shape of this.#selectedShapes) {
+        const shapeAlignments = this.#shapeToAlignments.get(shape);
+        if (shapeAlignments) {
+          for (const alignment of shapeAlignments) {
+            if (alignment.isHorizontal === isHorizontal) {
+              overlappingAlignments.add(alignment);
+            }
+          }
+        }
+      }
+
+      // Check if we've selected all shapes from multiple alignments
+      const allShapesSelected = Array.from(overlappingAlignments).every((alignment) =>
+        Array.from(alignment.shapes).every((shape) => this.#selectedShapes.has(shape)),
+      );
+
+      if (overlappingAlignments.size === 0) {
+        // Case: No overlapping alignments - create new alignment
+        this.#createAlignment(this.#selectedShapes);
+      } else if (overlappingAlignments.size === 1 || !allShapesSelected) {
+        // Case: One overlapping alignment or partial selection - merge into it
+        const existingAlignment = overlappingAlignments.values().next().value;
+        if (existingAlignment) {
+          this.#mergeIntoAlignment(existingAlignment, this.#selectedShapes);
+        }
+      } else {
+        // Case: Multiple complete alignments selected - merge all into new alignment
+        const allShapes = new Set<FolkShape>();
+        this.#selectedShapes.forEach((shape) => allShapes.add(shape));
+        overlappingAlignments.forEach((alignment) => {
+          alignment.shapes.forEach((shape) => allShapes.add(shape));
+          this.#removeAlignment(alignment);
+        });
+        this.#createAlignment(allShapes);
+      }
+    }
+
+    this.#isPointerDown = false;
+    this.#lastPointerPosition = null;
+    this.#selectedShapes.clear();
+  };
+
+  #isLineIntersectingRect(lineStart: Point, lineEnd: Point, rect: DOMRect): boolean {
+    // Simple AABB check
+    const minX = Math.min(lineStart.x, lineEnd.x);
+    const maxX = Math.max(lineStart.x, lineEnd.x);
+    const minY = Math.min(lineStart.y, lineEnd.y);
+    const maxY = Math.max(lineStart.y, lineEnd.y);
+
+    return !(maxX < rect.left || minX > rect.right || maxY < rect.top || minY > rect.bottom);
+  }
+
+  #createAlignment(shapes: Set<FolkShape>) {
+    if (shapes.size < 2) {
+      return;
+    }
+
+    // Calculate axis based on shape distribution
+    const centers = Array.from(shapes).map((shape) => shape.getTransformDOMRect().center);
+    const bounds = Vector.bounds(centers);
+    const isHorizontal = bounds.max.x - bounds.min.x > bounds.max.y - bounds.min.y;
+    const center = Vector.center(centers);
+
+    const positions = this.#calculateLinePoints(shapes, isHorizontal, center);
+    const alignment: AlignmentLine = {
+      shapes: new Set(shapes), // Create a new Set to avoid reference issues
+      isHorizontal,
+      ...positions,
+    };
+
+    // Update lookups
+    this.#alignments.add(alignment);
+    shapes.forEach((shape) => {
+      if (!this.#shapeToAlignments.has(shape)) {
+        this.#shapeToAlignments.set(shape, new Set());
+      }
+      this.#shapeToAlignments.get(shape)!.add(alignment);
+    });
+  }
+
+  #drawBrushStroke(from: Point, to: Point) {
+    this.#ctx.beginPath();
+    this.#ctx.moveTo(from.x, from.y);
+    this.#ctx.lineTo(to.x, to.y);
+    this.#ctx.lineWidth = this.#BRUSH_RADIUS;
+    this.#ctx.strokeStyle = 'rgba(150, 190, 255, 0.3)';
+    this.#ctx.lineCap = 'round';
+    this.#ctx.stroke();
+  }
+
+  #calculateLinePoints(
+    shapes: Set<FolkShape>,
+    isHorizontal: boolean,
+    centerPoint: Point,
+  ): {
+    points: Map<FolkShape, Point>;
+    lineStart: Point;
+    lineEnd: Point;
+  } {
+    const targetPositions = new Map<FolkShape, Point>();
+
+    // Get centers and calculate total extent
+    const shapeInfo = Array.from(shapes).map((shape) => {
+      const rect = shape.getTransformDOMRect();
+      return {
+        shape,
+        rect,
+        center: rect.center,
+        size: isHorizontal ? rect.width : rect.height,
+      };
+    });
+
+    // Sort shapes along the primary axis
+    shapeInfo.sort((a, b) => (isHorizontal ? a.center.x - b.center.x : a.center.y - b.center.y));
+
+    // Calculate total length including padding between shapes
+    const totalLength = shapeInfo.reduce((sum, info, index) => {
+      return sum + info.size + (index < shapeInfo.length - 1 ? this.#TARGET_PADDING : 0);
+    }, 0);
+
+    // Start position (centered around centerPoint)
+    let currentPos = -totalLength / 2;
+
+    // Calculate positions along the line
+    shapeInfo.forEach((info) => {
+      const point = isHorizontal
+        ? { x: centerPoint.x + currentPos + info.size / 2, y: centerPoint.y }
+        : { x: centerPoint.x, y: centerPoint.y + currentPos + info.size / 2 };
+
+      targetPositions.set(info.shape, point);
+      currentPos += info.size + this.#TARGET_PADDING;
+    });
+
+    // Calculate line extent (add padding to ends)
+    const halfLength = totalLength / 2;
+    const lineStart = isHorizontal
+      ? { x: centerPoint.x - halfLength, y: centerPoint.y }
+      : { x: centerPoint.x, y: centerPoint.y - halfLength };
+
+    const lineEnd = isHorizontal
+      ? { x: centerPoint.x + halfLength, y: centerPoint.y }
+      : { x: centerPoint.x, y: centerPoint.y + halfLength };
+
+    return {
+      points: targetPositions,
+      lineStart,
+      lineEnd,
+    };
+  }
+
+  #updateCanvas = () => {
+    // Clear canvas with fade effect
+    this.#ctx.fillStyle = 'rgba(255, 255, 255, 0.1)';
+    this.#ctx.fillRect(0, 0, this.#canvas.width, this.#canvas.height);
+
+    // Update shape positions
+    this.#lerpShapesTowardsTargets();
+
+    this.#visualizeAlignments();
+    requestAnimationFrame(this.#updateCanvas);
+  };
+
+  #lerpShapesTowardsTargets() {
+    // Check for dragged shapes that could join existing alignments
+    const activeShape = document.activeElement instanceof FolkShape ? document.activeElement : null;
+    if (activeShape && !this.#shapeToAlignments.has(activeShape)) {
+      const rect = activeShape.getTransformDOMRect();
+
+      // Find closest alignment within threshold
+      for (const alignment of this.#alignments) {
+        const perpDistance = alignment.isHorizontal
+          ? Math.abs(rect.center.y - alignment.lineStart.y)
+          : Math.abs(rect.center.x - alignment.lineStart.x);
+
+        const linePos = alignment.isHorizontal ? rect.center.x : rect.center.y;
+        const lineStart = alignment.isHorizontal ? alignment.lineStart.x : alignment.lineStart.y;
+        const lineEnd = alignment.isHorizontal ? alignment.lineEnd.x : alignment.lineEnd.y;
+
+        const threshold = (alignment.isHorizontal ? rect.height : rect.width) * this.#REMOVAL_THRESHOLD_MULTIPLIER;
+
+        if (perpDistance <= threshold && linePos >= lineStart && linePos <= lineEnd) {
+          this.#mergeIntoAlignment(alignment, new Set([activeShape]));
+          break;
+        }
+      }
+    }
+
+    // Existing alignment handling
+    for (const alignment of this.#alignments) {
+      alignment.shapes.forEach((shape) => {
+        if (shape === this.#draggedShape) {
+          // Handle dragged shape logic
+          const rect = shape.getTransformDOMRect();
+          const current = rect.center;
+
+          // Calculate perpendicular and parallel distances from line
+          const perpDistance = alignment.isHorizontal
+            ? Math.abs(current.y - alignment.lineStart.y)
+            : Math.abs(current.x - alignment.lineStart.x);
+
+          const linePos = alignment.isHorizontal ? current.x : current.y;
+          const lineStart = alignment.isHorizontal ? alignment.lineStart.x : alignment.lineStart.y;
+          const lineEnd = alignment.isHorizontal ? alignment.lineEnd.x : alignment.lineEnd.y;
+
+          // Calculate removal thresholds
+          const perpThreshold =
+            (alignment.isHorizontal ? rect.height : rect.width) * this.#REMOVAL_THRESHOLD_MULTIPLIER;
+
+          // Remove if too far perpendicular to line or beyond line endpoints
+          if (perpDistance > perpThreshold || linePos < lineStart || linePos > lineEnd) {
+            this.#removeShapeFromAlignment(shape, alignment);
+          } else {
+            // Recalculate positions while keeping the line fixed
+            const positions = this.#calculateLinePoints(alignment.shapes, alignment.isHorizontal, {
+              x: alignment.isHorizontal ? (alignment.lineStart.x + alignment.lineEnd.x) / 2 : alignment.lineStart.x,
+              y: alignment.isHorizontal ? alignment.lineStart.y : (alignment.lineStart.y + alignment.lineEnd.y) / 2,
+            });
+            alignment.points = positions.points;
+          }
+          return;
+        } else {
+          // Move non-dragged shapes
+          const target = alignment.points.get(shape)!;
+          const current = shape.getTransformDOMRect().center;
+          shape.x += (target.x - current.x) * 0.25;
+          shape.y += (target.y - current.y) * 0.25;
+        }
+      });
+    }
+  }
+
+  #removeShapeFromAlignment(shape: FolkShape, alignment: AlignmentLine) {
+    alignment.shapes.delete(shape);
+    alignment.points.delete(shape);
+
+    const shapeAlignments = this.#shapeToAlignments.get(shape);
+    if (shapeAlignments) {
+      shapeAlignments.delete(alignment);
+      if (shapeAlignments.size === 0) {
+        this.#shapeToAlignments.delete(shape);
+      }
+    }
+
+    // Remove alignment if less than 2 shapes remain
+    if (alignment.shapes.size < 2) {
+      this.#removeAlignment(alignment);
+    } else {
+      // Recalculate positions while keeping line fixed
+      const center = {
+        x: alignment.isHorizontal ? (alignment.lineStart.x + alignment.lineEnd.x) / 2 : alignment.lineStart.x,
+        y: alignment.isHorizontal ? alignment.lineStart.y : (alignment.lineStart.y + alignment.lineEnd.y) / 2,
+      };
+
+      const positions = this.#calculateLinePoints(alignment.shapes, alignment.isHorizontal, center);
+      alignment.points = positions.points;
+      alignment.lineStart = positions.lineStart;
+      alignment.lineEnd = positions.lineEnd;
+    }
+  }
+
+  #visualizeAlignments() {
+    Gizmos.clear();
+
+    // Show active alignments
+    for (const alignment of this.#alignments) {
+      const style = { color: 'blue', width: 2 };
+
+      // Draw alignment line
+      Gizmos.line(alignment.lineStart, alignment.lineEnd, style);
+
+      // Draw shape connections and targets
+      alignment.shapes.forEach((shape) => {
+        const rect = shape.getTransformDOMRect();
+        const current = rect.center;
+        const target = alignment.points.get(shape)!;
+
+        Gizmos.line(current, target, {
+          color: 'rgba(150, 150, 150, 0.5)',
+          width: 1,
+        });
+
+        Gizmos.point(target, {
+          color: style.color,
+          size: 4,
+        });
+      });
+    }
+
+    // Show potential alignment
+    if (this.#isPointerDown && this.#selectedShapes.size >= 2) {
+      const centers = Array.from(this.#selectedShapes).map((shape) => shape.getTransformDOMRect().center);
+      const bounds = Vector.bounds(centers);
+      const isHorizontal = bounds.max.x - bounds.min.x > bounds.max.y - bounds.min.y;
+      const center = Vector.center(centers);
+
+      const positions = this.#calculateLinePoints(this.#selectedShapes, isHorizontal, center);
+      const potential = {
+        shapes: this.#selectedShapes,
+        isHorizontal,
+        lineStart: positions.lineStart,
+        lineEnd: positions.lineEnd,
+        points: positions.points,
+      };
+
+      // Draw potential alignment
+      const style = { color: 'green', width: 2 };
+      Gizmos.line(potential.lineStart, potential.lineEnd, style);
+
+      potential.shapes.forEach((shape) => {
+        const rect = shape.getTransformDOMRect();
+        const current = rect.center;
+        const target = potential.points.get(shape)!;
+
+        Gizmos.line(current, target, {
+          color: 'rgba(150, 150, 150, 0.5)',
+          width: 1,
+        });
+
+        Gizmos.point(target, {
+          color: style.color,
+          size: 4,
+        });
+      });
+    }
+  }
+
+  // Helper methods to support the new functionality
+  #determineAlignment(shapes: Set<FolkShape>): boolean {
+    const centers = Array.from(shapes).map((shape) => shape.getTransformDOMRect().center);
+    const bounds = Vector.bounds(centers);
+    return bounds.max.x - bounds.min.x > bounds.max.y - bounds.min.y;
+  }
+
+  #mergeIntoAlignment(alignment: AlignmentLine, newShapes: Set<FolkShape>) {
+    // Add new shapes to existing alignment
+    newShapes.forEach((shape) => alignment.shapes.add(shape));
+
+    // Recalculate alignment positions while keeping line fixed
+    const center = {
+      x: alignment.isHorizontal ? (alignment.lineStart.x + alignment.lineEnd.x) / 2 : alignment.lineStart.x,
+      y: alignment.isHorizontal ? alignment.lineStart.y : (alignment.lineStart.y + alignment.lineEnd.y) / 2,
+    };
+
+    const positions = this.#calculateLinePoints(alignment.shapes, alignment.isHorizontal, center);
+    alignment.points = positions.points;
+    alignment.lineStart = positions.lineStart;
+    alignment.lineEnd = positions.lineEnd;
+
+    // Update shape-to-alignment mappings
+    newShapes.forEach((shape) => {
+      if (!this.#shapeToAlignments.has(shape)) {
+        this.#shapeToAlignments.set(shape, new Set());
+      }
+      this.#shapeToAlignments.get(shape)!.add(alignment);
+    });
+  }
+
+  #removeAlignment(alignment: AlignmentLine) {
+    // Remove from main set
+    this.#alignments.delete(alignment);
+
+    // Remove from all shape mappings
+    alignment.shapes.forEach((shape) => {
+      const alignments = this.#shapeToAlignments.get(shape);
+      if (alignments) {
+        alignments.delete(alignment);
+        if (alignments.size === 0) {
+          this.#shapeToAlignments.delete(shape);
+        }
+      }
+    });
+  }
+
+  // gross but here it is
+  #handleShapePointerDown = (event: PointerEvent) => {
+    if (event.target instanceof FolkShape) {
+      this.#draggedShape = event.target;
+    }
+  };
+
+  #handleShapePointerUp = () => {
+    this.#draggedShape = null;
+  };
+}

labs/standalone/folk-brush-field.ts

@@ -0,0 +1,5 @@
+import { FolkBrushField } from '../folk-brush-field';
+
+FolkBrushField.define();
+
+export { FolkBrushField };

lib/Vector.ts

@@ -11,6 +11,38 @@ export class Vector {
     return { x: 0, y: 0 };
   }
 
+  /**
+   * Unit vector pointing right (1,0)
+   * @returns {Point} A point representing a right vector
+   */
+  static right(): Point {
+    return { x: 1, y: 0 };
+  }
+
+  /**
+   * Unit vector pointing left (-1,0)
+   * @returns {Point} A point representing a left vector
+   */
+  static left(): Point {
+    return { x: -1, y: 0 };
+  }
+
+  /**
+   * Unit vector pointing up (0,-1)
+   * @returns {Point} A point representing an up vector
+   */
+  static up(): Point {
+    return { x: 0, y: -1 };
+  }
+
+  /**
+   * Unit vector pointing down (0,1)
+   * @returns {Point} A point representing a down vector
+   */
+  static down(): Point {
+    return { x: 0, y: 1 };
+  }
+
   /**
    * Subtracts vector b from vector a
    * @param {Point} a - The first vector
@@ -190,4 +222,44 @@ export class Vector {
   static magSquared(v: Point): number {
     return v.x * v.x + v.y * v.y;
   }
+
+  /**
+   * Calculates the bounding box of a set of points
+   * @param {Point[]} points - Array of points to find bounds for
+   * @returns {{ min: Point, max: Point }} Object containing min and max points of the bounds
+   */
+  static bounds(points: Point[]): { min: Point; max: Point } {
+    return points.reduce(
+      (acc, p) => ({
+        min: { x: Math.min(acc.min.x, p.x), y: Math.min(acc.min.y, p.y) },
+        max: { x: Math.max(acc.max.x, p.x), y: Math.max(acc.max.y, p.y) },
+      }),
+      { min: { x: Infinity, y: Infinity }, max: { x: -Infinity, y: -Infinity } },
+    );
+  }
+
+  /**
+   * Calculates the center point of a set of points
+   * @param {Point[]} points - Array of points to find center for
+   * @returns {Point} The center point
+   */
+  static center(points: Point[]): Point {
+    const bounds = Vector.bounds(points);
+    return {
+      x: (bounds.min.x + bounds.max.x) / 2,
+      y: (bounds.min.y + bounds.max.y) / 2,
+    };
+  }
+
+  /**
+   * Projects a point onto an axis
+   * @param {Point} point - The point to project
+   * @param {Point} axis - The axis to project onto
+   * @returns {Point} The projected point
+   */
+  static project(point: Point, axis: Point): Point {
+    const normalized = Vector.normalized(axis);
+    const dot = point.x * normalized.x + point.y * normalized.y;
+    return Vector.scale(normalized, dot);
+  }
 }

lib/folk-gizmos.ts

@@ -1,5 +1,6 @@
 import { DOMRectTransform, FolkElement, type Point } from '@lib';
 import { html } from '@lib/tags';
+import { Vector } from '@lib/Vector';
 import { css } from '@lit/reactive-element';
 
 interface GizmoOptions {
@@ -49,6 +50,7 @@ export class Gizmos extends FolkElement {
     {
       ctx: CanvasRenderingContext2D;
       canvas: HTMLCanvasElement;
+      hidden: boolean;
     }
   >();
   static #defaultLayer = 'default';
@@ -75,10 +77,12 @@ export class Gizmos extends FolkElement {
   `;
 
   readonly #layer: string;
+  #hidden: boolean;
 
   constructor() {
     super();
     this.#layer = this.getAttribute('layer') ?? Gizmos.#defaultLayer;
+    this.#hidden = this.hasAttribute('hidden');
   }
 
   override createRenderRoot() {
@@ -90,7 +94,7 @@ export class Gizmos extends FolkElement {
     const ctx = canvas?.getContext('2d') ?? null;
 
     if (canvas && ctx) {
-      Gizmos.#layers.set(this.#layer, { canvas, ctx });
+      Gizmos.#layers.set(this.#layer, { canvas, ctx, hidden: this.#hidden });
     }
 
     this.#handleResize();
@@ -155,37 +159,47 @@ export class Gizmos extends FolkElement {
     ctx.stroke();
   }
 
-  /** Draws a vector with an arrow head */
+  /**
+   * Draws a vector with an arrow head starting from `origin`.
+   * @param origin The starting point
+   * @param vector The vector endpoint in local coordinates relative to origin
+   */
   static vector(
     origin: Point,
-    vector: Point,
+    localEndpoint: Point,
     { color = 'blue', width = 2, size = 10, layer = Gizmos.#defaultLayer }: VectorOptions = {},
   ) {
     const ctx = Gizmos.#getContext(layer);
     if (!ctx) return;
 
-    // Calculate angle and length
-    const angle = Math.atan2(vector.y - origin.y, vector.x - origin.x);
-    const arrowAngle = Math.PI / 6; // 30 degrees
+    // Convert local endpoint to global coordinates
+    const globalEndpoint = Vector.add(origin, localEndpoint);
+
+    // Calculate angle and normalized direction
+    const angle = Vector.angle(localEndpoint);
+    const length = Vector.mag(localEndpoint);
 
     // Calculate where the line should end (where arrow head begins)
-    const lineEndX = vector.x - size * Math.cos(angle);
-    const lineEndY = vector.y - size * Math.sin(angle);
+    const lineEnd = Vector.add(origin, Vector.scale(Vector.normalized(localEndpoint), length - size));
 
     // Draw the main line
     ctx.beginPath();
     ctx.strokeStyle = color;
     ctx.lineWidth = width;
     ctx.moveTo(origin.x, origin.y);
-    ctx.lineTo(lineEndX, lineEndY);
+    ctx.lineTo(lineEnd.x, lineEnd.y);
     ctx.stroke();
 
     // Draw arrow head as a connected triangle
+    const arrowAngle = Math.PI / 6; // 30 degrees
+    const leftPoint = Vector.add(globalEndpoint, Vector.rotate({ x: -size, y: 0 }, angle - arrowAngle));
+    const rightPoint = Vector.add(globalEndpoint, Vector.rotate({ x: -size, y: 0 }, angle + arrowAngle));
+
     ctx.beginPath();
-    ctx.moveTo(vector.x, vector.y); // Tip of the arrow
-    ctx.lineTo(vector.x - size * Math.cos(angle - arrowAngle), vector.y - size * Math.sin(angle - arrowAngle));
-    ctx.lineTo(vector.x - size * Math.cos(angle + arrowAngle), vector.y - size * Math.sin(angle + arrowAngle));
-    ctx.lineTo(vector.x, vector.y); // Back to the tip
+    ctx.moveTo(globalEndpoint.x, globalEndpoint.y);
+    ctx.lineTo(leftPoint.x, leftPoint.y);
+    ctx.lineTo(rightPoint.x, rightPoint.y);
+    ctx.lineTo(globalEndpoint.x, globalEndpoint.y);
     ctx.fillStyle = color;
     ctx.fill();
   }
@@ -219,19 +233,47 @@ export class Gizmos extends FolkElement {
     ctx.scale(dpr, dpr);
   }
 
+  static #log() {
+    return {
+      message: '',
+      styles: [] as string[],
+
+      text(str: string) {
+        this.message += str;
+        return this;
+      },
+
+      color(str: string, color: string) {
+        this.message += '%c' + str + '%c';
+        this.styles.push(`font-weight: bold; color: ${color}`, '');
+        return this;
+      },
+
+      print() {
+        console.info(this.message, ...this.styles);
+      },
+    };
+  }
+
   static #getContext(layer = Gizmos.#defaultLayer) {
     if (!Gizmos.#hasLoggedInitMessage) {
       const gizmos = document.querySelectorAll<Gizmos>(Gizmos.tagName);
-      console.info(
-        '%cGizmos',
-        'font-weight: bold; color: #4CAF50;',
-        '\n• Gizmo elements:',
-        gizmos.length,
-        '\n• Layers:',
-        `[${Array.from(Gizmos.#layers.keys()).join(', ')}]`,
-        '\n• Default layer:',
-        Gizmos.#defaultLayer,
-      );
+      const layers = Array.from(Gizmos.#layers.entries());
+
+      const log = Gizmos.#log()
+        .color('Gizmos', '#4CAF50')
+        .text('\n• Gizmo elements: ' + gizmos.length)
+        .text('\n• Layers: [');
+
+      layers.forEach(([key, value], i) => {
+        if (i > 0) log.text(', ');
+        log.text(key);
+        if (value.hidden) {
+          log.color(' (hidden)', '#FFA500');
+        }
+      });
+
+      log.text(']').print();
       Gizmos.#hasLoggedInitMessage = true;
     }
 
@@ -242,7 +284,7 @@ export class Gizmos extends FolkElement {
       return null;
     }
 
-    return layerData?.ctx;
+    return layerData?.hidden ? null : layerData?.ctx;
   }
 }
 

lib/index.ts

@@ -8,6 +8,7 @@ export * from './folk-observer';
 export * from './resize-manger';
 
 // Core utilities and types
+export * from './folk-gizmos';
 export * from './Matrix';
 export * from './types';
 export * from './Vector';

website/canvas/event-propagators-with-device-gravity.html

@@ -130,8 +130,8 @@ rotation: from.x"
         Gizmos.vector(
           center,
           {
-            x: center.x + gravity.x / 10,
-            y: center.y + gravity.y / 10,
+            x: gravity.x / 10,
+            y: gravity.y / 10,
           },
           { color: 'grey', width: 3, size: 15 },
         );

website/canvas/field-effect-brush.html

@@ -0,0 +1,55 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Brush Field Demo</title>
+    <style>
+      html {
+        height: 100%;
+      }
+
+      body {
+        min-height: 100%;
+        position: relative;
+        margin: 0;
+        overscroll-behavior: none;
+      }
+
+      folk-shape {
+        position: absolute;
+        background-color: rgba(255, 255, 255, 0.8);
+        border-radius: 2px;
+        border: 2px solid rgba(0, 0, 0, 0.5);
+      }
+
+      folk-brush-field {
+        pointer-events: all;
+      }
+    </style>
+  </head>
+  <body>
+    <folk-gizmos></folk-gizmos>
+    <folk-brush-field>
+      <folk-shape x="100" y="100" width="50" height="50"></folk-shape>
+      <folk-shape x="100" y="200" width="50" height="50"></folk-shape>
+      <folk-shape x="100" y="300" width="50" height="50"></folk-shape>
+      <folk-shape x="300" y="150" width="80" height="40"></folk-shape>
+      <folk-shape x="400" y="250" width="60" height="90"></folk-shape>
+      <folk-shape x="200" y="400" width="100" height="100"></folk-shape>
+      <folk-shape x="500" y="100" width="30" height="70"></folk-shape>
+      <folk-shape x="600" y="300" width="70" height="70"></folk-shape>
+      <folk-shape x="250" y="50" width="45" height="65"></folk-shape>
+      <folk-shape x="450" y="400" width="90" height="40"></folk-shape>
+      <folk-shape x="550" y="200" width="40" height="120"></folk-shape>
+      <folk-shape x="150" y="500" width="55" height="55"></folk-shape>
+      <folk-shape x="350" y="350" width="75" height="45"></folk-shape>
+    </folk-brush-field>
+
+    <script type="module">
+      import '@labs/standalone/folk-shape.ts';
+      import '@labs/standalone/folk-brush-field.ts';
+      import { Gizmos } from '@lib/folk-gizmos.ts';
+    </script>
+  </body>
+</html>

website/canvas/physics-mobile-gravity.html

@@ -99,8 +99,8 @@
         Gizmos.vector(
           center,
           {
-            x: center.x + gravity.x / 2,
-            y: center.y + gravity.y / 2,
+            x: gravity.x / 2,
+            y: gravity.y / 2,
           },
           { color: 'grey', width: 3, size: 15 },
         );