feuerwerk/src/core/properties/bounds.ts

/**
 * Footprints in world units, shared by the viewport, by pointer hit tests in the running game and by
 * "Add collider", so all three agree on how big a thing is – and, through the object's transform, on
 * where its corners are.
 */
import { type AssetType, hasSceneIcon } from '../model/AssetTypes';
import type { FrameOutline } from '../model/frameOutline';
import {
  apply,
  boxCorners,
  type Extent,
  extentOfPoints,
  invert,
  type Mat,
  scaleOf,
  translation,
} from '../model/matrix';
import { type PropertyBag, textOf, type Vec2 } from '../model/Properties';
import { tilemapSize } from '../model/tilemap';
import { cameraFrame } from './camera';
import { colliderSize } from './collider';
import { defaultsFor } from './PropertySchema';

const TEXT_DEFAULTS = defaultsFor('text');

/** Symbol sizes in world units. */
export const BEHAVIOR_SYMBOL = 28;
export const CONTAINER_SYMBOL = 24;
export const PARTICLES_SYMBOL = 24;
export const RIGIDBODY_SYMBOL = 24;

/** Rough width of one character relative to the font size, for a plain sans. */
const CHAR_WIDTH = 0.55;
const LINE_HEIGHT = 1.25;

/** Estimated from the content and font size, without measuring the text. */
export function textSize(props: PropertyBag): { w: number; h: number } {
  const size = Math.max(1, Number(props.fontSize ?? TEXT_DEFAULTS.fontSize));
  const lines = textOf(props.text ?? TEXT_DEFAULTS.text).split('\n');
  const longest = lines.reduce((max, line) => Math.max(max, line.length), 0);
  return {
    w: Math.max(size * CHAR_WIDTH, longest * size * CHAR_WIDTH),
    h: lines.length * size * LINE_HEIGHT,
  };
}

/** 0 = left edge on the position, 0.5 = centred, 1 = right. */
export function textAnchor(props: PropertyBag): number {
  const align = textOf(props.align ?? TEXT_DEFAULTS.align);
  return align === 'left' ? 0 : align === 'right' ? 1 : 0.5;
}

/**
 * Centred on the object's position; text is anchored instead (see `textAnchor`). A collider that
 * wears a frame (#193) is that frame's size, which only the caller can look up.
 */
export function footprintOf(
  type: AssetType,
  props: PropertyBag,
  frame?: FrameOutline | null,
): { w: number; h: number } {
  switch (type) {
    case 'sprite':
      return { w: Number(props.width ?? 1), h: Number(props.height ?? 1) };
    case 'text':
      return textSize(props);
    case 'collider':
      return colliderSize(props, frame);
    case 'behavior':
      return { w: BEHAVIOR_SYMBOL, h: BEHAVIOR_SYMBOL };
    case 'container':
      return { w: CONTAINER_SYMBOL, h: CONTAINER_SYMBOL };
    case 'rigidbody':
      return { w: RIGIDBODY_SYMBOL, h: RIGIDBODY_SYMBOL };
    // The particles themselves are drawn wherever the graph puts them; what can be grabbed and
    // framed is the source, which is a point with a handle around it.
    case 'particles':
      return { w: PARTICLES_SYMBOL, h: PARTICLES_SYMBOL };
    // The whole grid, centred on the object's position like every other footprint – so its cells
    // are the same squares for drawing, for picking and for the outline around it.
    case 'tilemap':
      return tilemapSize(props);
    default:
      return cameraFrame(props);
  }
}

/**
 * How an item of this type is drawn: with its whole transform, or – for the icons of behaviors,
 * containers, particle sources and the camera frame – upright and unscaled at its position, since an
 * icon that turns with its parent would only be harder to read. A source's own frame still goes into
 * every particle; what stays upright is the square that can be grabbed, so it covers its icon.
 * Colliders are symbols too but follow their body.
 */
export function placementOf(type: AssetType, m: Mat): Mat {
  return hasSceneIcon(type) && type !== 'collider' ? translation(m.tx, m.ty) : m;
}

function anchorOffset(type: AssetType, props: PropertyBag, w: number): number {
  return type === 'text' ? (0.5 - textAnchor(props)) * w : 0;
}

/** The footprint's corners in world units, grown by `pad` world units on every side. */
export function footprintCorners(
  type: AssetType,
  props: PropertyBag,
  m: Mat,
  pad = 0,
  frame?: FrameOutline | null,
): Vec2[] {
  const placed = placementOf(type, m);
  const { w, h } = footprintOf(type, props, frame);
  const local = pad / (scaleOf(placed) || 1);
  return boxCorners(placed, w + 2 * local, h + 2 * local, anchorOffset(type, props, w), 0);
}

/** The world rectangle around the drawn footprint – what culling, framing and labels need. */
export function footprintExtent(
  type: AssetType,
  props: PropertyBag,
  m: Mat,
  frame?: FrameOutline | null,
): Extent {
  return extentOfPoints(footprintCorners(type, props, m, 0, frame));
}

export function footprintContains(type: AssetType, props: PropertyBag, m: Mat, point: Vec2): boolean {
  const { w, h } = footprintOf(type, props);
  const local = apply(invert(placementOf(type, m)), point);
  return Math.abs(local.x - anchorOffset(type, props, w)) <= w / 2 && Math.abs(local.y) <= h / 2;
}