feat: add in creature rendering

static/index.js

@@ -1,5 +1,217 @@
-window.onload = () => {
+const CREATURE_HEIGHT = 32; // in px
-    console.log('from js');
+const CREATURE_WIDTH = 32; // in px
-    const kennelWindowEle = document.querySelector('#kennel-window');
+const FRAME_RATE = 12; // in FPS
-    kennelWindowEle.innerHTML = 'rendered from static/index.js';
+const FRAME_DELAY = 1 / FRAME_RATE * 1000; // in ms
+const DEFAULT_SPRITE_SHEET_COUNT = 1; // number of default sprite sheets
+
+/**
+ * Enum of creature states
+ * @readonly
+ * @enum {number}
+ */
+const CreatureState = Object.freeze({
+    IDLE: 0,
+    ALERT: 1,
+    SCRATCH_SELF: 2,
+    SCRATCH_NORTH: 3,
+    SCRATCH_SOUTH: 4,
+    SCRATCH_EAST: 5,
+    SCRATCH_WEST: 6,
+    TIRED: 7,
+    SLEEPING: 8,
+    WALK_NORTH: 9,
+    WALK_NORTHEAST: 10,
+    WALK_EAST: 11,
+    WALK_SOUTHEAST: 12,
+    WALK_SOUTH: 13,
+    WALK_SOUTHWEST: 14,
+    WALK_WEST: 15,
+    WALK_NORTHWEST: 16,
+})
+
+/**
+ * @typedef {[number, number]} SpriteFrameOffset the offset of the sprite with respect to
+ *                                               the left/top background position offset (off by factor of sprite size)
+ * @type {Object.<number, Array<SpriteFrameOffset>>}
+ */
+const CREATURE_STATE_TO_SPRITE_FRAME_OFFSET_INDICES = Object.freeze({
+    [CreatureState.IDLE]: [
+        [-3, -3]
+    ],
+    [CreatureState.ALERT]: [
+        [-7, -3]
+    ],
+    [CreatureState.SCRATCH_SELF]: [
+        [-5, 0],
+        [-6, 0],
+        [-7, 0],
+    ],
+    [CreatureState.SCRATCH_NORTH]: [
+        [0, 0],
+        [0, -1],
+    ],
+    [CreatureState.SCRATCH_SOUTH]: [
+        [-7, -1],
+        [-6, -2],
+    ],
+    [CreatureState.SCRATCH_EAST]: [
+        [-2, -2],
+        [-2, -3],
+    ],
+    [CreatureState.SCRATCH_WEST]: [
+        [-4, 0],
+        [-4, -1],
+    ],
+    [CreatureState.TIRED]: [
+        [-3, -2]
+    ],
+    [CreatureState.SLEEPING]: [
+        [-2, 0],
+        [-2, -1],
+    ],
+    [CreatureState.WALK_NORTH]: [
+        [-1, -2],
+        [-1, -3],
+    ],
+    [CreatureState.WALK_NORTHEAST]: [
+        [0, -2],
+        [0, -3],
+    ],
+    [CreatureState.WALK_EAST]: [
+        [-3, 0],
+        [-3, -1],
+    ],
+    [CreatureState.WALK_SOUTHEAST]: [
+        [-5, -1],
+        [-5, -2],
+    ],
+    [CreatureState.WALK_SOUTH]: [
+        [-6, -3],
+        [-7, -2],
+    ],
+    [CreatureState.WALK_SOUTHWEST]: [
+        [-5, -3],
+        [-6, -1],
+    ],
+    [CreatureState.WALK_WEST]: [
+        [-4, -2],
+        [-4, -3],
+    ],
+    [CreatureState.WALK_NORTHWEST]: [
+        [-1, 0],
+        [-1, -1],
+    ],
+});
+
+/**
+ * Properties for creatures running around the screen
+ * @typedef {Object} Creature
+ * @property {string} name the name of the creature, used as the HTML element's id
+ * @property {string} spriteSheet the file name of the sprite sheet. should exist in {@link /static/sprites}
+ * @property {number} state the current state of the creature (should be member of {@link CreatureState} enum)
+ * @property {number} stateDuration the number of frames the creature has been in its current state
+ * @property {number} positionX the number of pixels away from the left side of the container element
+ * @property {number} positionY the number of pixels away from the top of the container element
+ * @property {HTMLElement} element the HTML element rendering the creature in the DOM
+ * @property {HTMLElement} container the HTML element containing the creature (the kennel, if you will)
+ */
+
+/**
+ * Returns random number between min (inclusive) and max (exclusive)
+ * If max is less than or equal to min, return min
+ * @param {number} min inclusive lower bound
+ * @param {number} max exclusive upper bound
+ * @return {number} number in [min, max)
+ */
+const randomInt = (min, max) => {
+    if (max <= min) return min;
+    return Math.floor(Math.random() * (max - min) + min);
+}
+
+/**
+ * Return a creature's next frame based on the current creature frame
+ * @param {Creature} creature
+ * @return Creature the next frame of the creature
+ */
+const getNextCreatureFrame = (creature) => {
+    // TODO
+    return { ...creature, stateDuration: creature.stateDuration + 1 };
+}
+
+/**
+ * Render a frame of the creature and loads the next frame for render
+ * @param {Creature} creature
+ * @return Creature the next frame of the creature
+ */
+const renderCreature = (creature) => {
+    // set position
+    const positionX = Math.min(creature.positionX, creature.container.clientWidth);
+    const positionY = Math.min(creature.positionY, creature.container.clientHeight);
+    creature.element.style.setProperty('left', `${positionX}px`);
+    creature.element.style.setProperty('top', `${positionY}px`);
+
+    // set sprite
+    const spriteFrames = CREATURE_STATE_TO_SPRITE_FRAME_OFFSET_INDICES[creature.state]
+    const currentSpriteFrameOffset = spriteFrames?.[creature.stateDuration % spriteFrames.length]
+    creature.element.style.setProperty(
+      'background-position',
+      `${currentSpriteFrameOffset[0] * CREATURE_WIDTH}px ${currentSpriteFrameOffset[1] * CREATURE_HEIGHT}px`
+    )
+
+    const nextCreatureFrame = getNextCreatureFrame(creature);
+    setTimeout(renderCreature, FRAME_DELAY, nextCreatureFrame)
+}
+
+/**
+ * Create the creature and start its rendering
+ * @param {HTMLElement} container container element for creatures. the kennel if you will
+ * @param {string} name name of the creature
+ * @param {string} [spriteSheet] name of the sprite sheet. must be in /static/sprites
+ *                                         uses default sprite sheet if undefined
+ * @param {number} [initialState] starting state of the creature
+ * @param {number} [initialPositionX] initial x position in pixels (from the left side)
+ * @param {number} [initialPositionY] initial y position in pixels (from the top)
+ */
+const createCreature = (
+  container,
+  name,
+  spriteSheet,
+  initialState = CreatureState.IDLE,
+  initialPositionX = 0,
+  initialPositionY = 0
+) => {
+    const creatureEl = document.createElement('div');
+    const spriteSheetUrl = spriteSheet
+        ? `url('/static/sprites/${spriteSheet}')`
+        : `url('/static/sprites/defaults/${randomInt(1, DEFAULT_SPRITE_SHEET_COUNT)}.gif')`;
+
+    creatureEl.setAttribute('id', name);
+    creatureEl.style.setProperty('width', `${CREATURE_WIDTH}px`);
+    creatureEl.style.setProperty('height', `${CREATURE_HEIGHT}px`);
+    creatureEl.style.setProperty('position', 'fixed');
+    creatureEl.style.setProperty('image-rendering', 'pixelated');
+    creatureEl.style.setProperty('background-image', spriteSheetUrl);
+
+    container.appendChild(creatureEl);
+
+    renderCreature({
+        name,
+        spriteSheet,
+        state: initialState,
+        stateDuration: 0,
+        positionX: Math.max(0, initialPositionX),
+        positionY: Math.max(0, initialPositionY),
+        element: creatureEl,
+        container
+    });
+}
+
+window.onload = () => {
+    const kennelWindowEle = document.querySelector('#kennel-window');
+    createCreature(
+      kennelWindowEle,
+      'test-creature',
+      undefined,
+      CreatureState.SCRATCH_SELF
+    )
 }

static/style.css

@@ -0,0 +1,7 @@
+#kennel-window {
+    width: 80vw;
+    min-width: 8rem;
+    height: 80vw;
+    min-height: 8rem;
+    margin: auto inherit;
+}

templates/index.html

@@ -4,6 +4,7 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <meta http-equiv="X-UA-Compatible" content="ie=edge">
+    <link rel="stylesheet" href="{{ url_for('static', path='style.css') }}">
     <title>Kennel Club</title>
   </head>
   <body>