Grid system & simple physics

12 files changed, 185 insertions, 53 deletions

diff --git a/src/bootstrap.js b/src/bootstrap.js
index 657067c..fc06962 100644
--- a/src/bootstrap.js
+++ b/src/bootstrap.js
@@ -1,30 +1,32 @@
 game.bootstrap = (() => {
   const scripts = [
-    { src: ['src/render/graphics.js'], id: 'render' },
-    { src: ['src/components/component.js', 'src/components/position.js', 'src/components/appearence.js'], id: 'components' },
-    { src: ['src/entities/entity.js'],      id: 'entity' },
-    { src: ['src/entities/bigblue.js'],     id: 'entities' },
-    { src: ['src/entities/flag.js'],        id: 'entities' },
-    { src: ['src/entities/floor.js'],       id: 'entities' },
-    { src: ['src/entities/grass.js'],       id: 'entities' },
-    { src: ['src/entities/hedge.js'],       id: 'entities' },
-    { src: ['src/entities/liquid.js'],      id: 'entities' },
-    { src: ['src/entities/rock.js'],        id: 'entities' },
-    { src: ['src/entities/wall.js'],        id: 'entities' },
-    { src: ['src/entities/wordBigBlue.js'], id: 'entities' },
-    { src: ['src/entities/wordFlag.js'],    id: 'entities' },
-    { src: ['src/entities/wordIs.js'],      id: 'entities' },
-    { src: ['src/entities/wordKill.js'],    id: 'entities' },
-    { src: ['src/entities/wordLava.js'],    id: 'entities' },
-    { src: ['src/entities/wordPush.js'],    id: 'entities' },
-    { src: ['src/entities/wordRock.js'],    id: 'entities' },
-    { src: ['src/entities/wordSink.js'],    id: 'entities' },
-    { src: ['src/entities/wordStop.js'],    id: 'entities' },
-    { src: ['src/entities/wordWall.js'],    id: 'entities' },
-    { src: ['src/entities/wordWater.js'],   id: 'entities' },
-    { src: ['src/entities/wordWin.js'],     id: 'entities' },
-    { src: ['src/entities/wordYou.js'],     id: 'entities' },
-    { src: ['src/systems/render.js'], id: 'systems' },
+    { src: ['src/utils/objectEquivalence.js', 'src/utils/unitizeVector.js'], id: 'utils'},
+    { src: ['src/render/graphics.js'], id: 'graphics' },
+    { src: ['src/components/component.js'], id: 'component' },
+    { 
+      src: [
+        'src/components/position.js', 'src/components/momentum.js', 'src/components/gridPosition.js',
+        'src/components/appearence.js'
+      ],
+      id: 'components'
+    },
+    { src: ['src/entities/entity.js'], id: 'entity' },
+    { 
+      src: [
+        'src/entities/bigblue.js', 'src/entities/flag.js', 'src/entities/floor.js', 'src/entities/grass.js', 'src/entities/hedge.js',
+        'src/entities/liquid.js', 'src/entities/rock.js', 'src/entities/wall.js', 'src/entities/wordBigBlue.js', 
+        'src/entities/wordFlag.js', 'src/entities/wordIs.js', 'src/entities/wordKill.js', 'src/entities/wordLava.js',
+        'src/entities/wordPush.js', 'src/entities/wordRock.js', 'src/entities/wordSink.js', 'src/entities/wordStop.js', 
+        'src/entities/wordWall.js', 'src/entities/wordWater.js', 'src/entities/wordWin.js', 'src/entities/wordYou.js'
+      ],
+      id: 'entities'
+    },
+    { src: ['src/systems/system.js'], id: 'system' },
+    { 
+      src: [
+        'src/systems/render.js', 'src/systems/gridSystem.js', 'src/systems/physics.js'
+      ],
+      id: 'systems' },
     { src: ['src/game.js'], id: 'game' },
   ];
   const assets = {};
diff --git a/src/components/gridPosition.js b/src/components/gridPosition.js
new file mode 100644
index 0000000..ede4b23
--- /dev/null
+++ b/src/components/gridPosition.js
@@ -0,0 +1 @@
+game.components.GridPosition = ({x, y}) => game.Component('gridPosition', {x, y});
\ No newline at end of file
diff --git a/src/components/momentum.js b/src/components/momentum.js
new file mode 100644
index 0000000..b974aa7
--- /dev/null
+++ b/src/components/momentum.js
@@ -0,0 +1 @@
+game.components.Momentum = ({dx, dy}) => game.Component('momentum', {dx, dy});
\ No newline at end of file
diff --git a/src/entities/entity.js b/src/entities/entity.js
index 33d1031..1eb5223 100644
--- a/src/entities/entity.js
+++ b/src/entities/entity.js
@@ -5,13 +5,14 @@ game.Entity = (id=game.nextId++) => {
 
   const addComponent = (component) => {
     components[component.name] = component;
-  }
-  const removeComponent = (component) => {
-    delete components[component.name];
-  }
-  const hasComponent = (component) => {
-    components[component.name] !== undefined;
-  }
+  };
+  const hasComponent = (componentName) => components[componentName] !== undefined;
+  const removeComponent = (componentName) => {
+    if (hasComponent(componentName)) {
+      delete components[componentName];
+    }
+  };
+  
 
   return {
     id,
diff --git a/src/game.js b/src/game.js
index cd82cc0..9cf60c6 100644
--- a/src/game.js
+++ b/src/game.js
@@ -1,20 +1,41 @@
-game.loop = (elapsedTime) => {
-  game.systems.Render.update(elapsedTime);
+let lastTimeStamp;
+game.loop = (timeStamp) => {
+  let elapsedTime = timeStamp - lastTimeStamp;
+  lastTimeStamp = timeStamp;
+
+  game.systemOrder.map((i) => {
+    game.systems[i].update(elapsedTime, game.entities);
+  });
 
   requestAnimationFrame(game.loop);
 }
 
 game.initialize = () => {
+  game.systemOrder = ["render", "physics", "gridSystem"];
+  game.systems = {
+    render: game.system.Render(game.graphics),
+    physics: game.system.Physics(),
+    gridSystem: game.system.GridSystem({
+      xDim: 15,
+      yDim: 15,
+      canvasWidth: game.canvas.width,
+      canvasHeight: game.canvas.height,
+    }),
+  };
+
   game.entities = {};
-  game.bigBlue = game.createBigBlue();
-  game.entities[game.bigBlue.id] = game.bigBlue;
-  game.bigBlue2 = game.createBigBlue();
-  game.bigBlue2.components.position = game.components.Position({x: 200, y: 100});
-  game.entities[game.bigBlue2.id] = game.bigBlue2;
+
+  Array(400).fill(null).forEach((_, i) => {
+    const bigBlue = game.createBigBlue();
+    bigBlue.addComponent(game.components.GridPosition({x: Math.floor(Math.random() * 15), y: Math.floor(Math.random() * 13)}));
+    game.entities[bigBlue.id] = bigBlue;
+  });
 
   game.rock = game.createRock();
-  game.rock.components.position = game.components.Position({x: 200, y: 200});
+  game.rock.addComponent(game.components.Position({x: 200, y: 200}));
+  game.rock.addComponent(game.components.GridPosition({x: 0, y: 0}));
   game.entities[game.rock.id] = game.rock;
 
+  lastTimeStamp = performance.now()
   requestAnimationFrame(game.loop);
 }
diff --git a/src/render/graphics.js b/src/render/graphics.js
index de98633..6a199f0 100644
--- a/src/render/graphics.js
+++ b/src/render/graphics.js
@@ -3,10 +3,9 @@ game.graphics = (
   (context) => {
     context.imageSmoothingEnabled = false;
     const clear = () => {
-      context.clearRect(0, 0, game.width, game.height);
+      context.clearRect(0, 0, game.canvas.width, game.canvas.height);
     };
     
-    // Maybe this should be a component?
     const Sprite = ({image, spriteX, spriteY, spriteWidth, spriteHeight, timePerFrame, cols, rows, numFrames, drawFunction}) => {
       timePerFrame = timePerFrame ?? 100;
       numFrames = numFrames ?? 1;
diff --git a/src/systems/gridSystem.js b/src/systems/gridSystem.js
new file mode 100644
index 0000000..05ce17e
--- /dev/null
+++ b/src/systems/gridSystem.js
@@ -0,0 +1,73 @@
+game.system.GridSystem = ({ xDim, yDim, canvasWidth, canvasHeight }) => {
+  const entitiesGrid = Array(yDim).fill(null).map(() => Array(xDim).fill(null).map(() => new Map()));
+
+  const gridWidth = canvasWidth / xDim;
+  const gridHeight = canvasHeight / yDim;
+
+  const gameCoordsToGrid = ({ x, y }) => {
+    return { x: Math.floor((x+gridWidth/2) / canvasWidth * xDim), y: Math.floor((y+gridHeight/2) / canvasHeight * yDim) };
+  };
+
+  const gridCoordsToGame = ({ x, y }) => {
+    return { x: x * gridWidth, y: y * gridHeight };
+  };
+
+  const rebuildGrid = (entities) => {
+    let changedIds = new Set();
+    entities.map(entity => {
+      const { x, y } = entity.components.gridPosition;
+      if (!entitiesGrid[y][x].has(entity.id)) {
+        changedIds.add(entity.id);
+      }
+    });
+    entitiesGrid.forEach((row) => row.forEach((entitiesInCell) => {
+      for (let id of entitiesInCell.keys()) {
+        if (changedIds.has(id)) {
+          entitiesInCell.delete(id);
+        }
+      }
+    }));
+    changedIds.forEach(id => {
+      const entity = entities[id];
+      const { x, y } = entity.components.gridPosition;
+      entitiesGrid[y][x].set(entity.id, entity);
+    });
+  }
+
+  const update = (_elapsedTime, entities) => {
+    const gridEntities = Object.keys(entities).filter((x) => entities[x].hasComponent("gridPosition")).map((x) => entities[x]);
+    rebuildGrid(gridEntities);
+    gridEntities.map((entity) => {
+      if (entity.hasComponent("appearance")) {
+        entity.components.appearance.width = canvasWidth / xDim;
+        entity.components.appearance.height = canvasHeight / yDim;
+      }
+      if (entity.hasComponent("position")) {
+        const newGridCoords = gameCoordsToGrid(entity.components.position);
+        const oldGridCoords = entity.components.gridPosition;
+        if (!equivalence(newGridCoords, oldGridCoords)) {
+          const momentumVector = unitize({ 
+            dx: newGridCoords.x - oldGridCoords.x,
+            dy: newGridCoords.y - oldGridCoords.y,
+          });
+
+          // TODO: Loop in momentum direction until we find an entity that does not have "push" component
+          entity.components.gridPosition.x = entity.components.gridPosition.x + momentumVector.dx;
+          entity.components.gridPosition.y = entity.components.gridPosition.y + momentumVector.dy;
+
+          entity.components.position = {
+            ...entity.components.position,
+            ...gridCoordsToGame(entity.components.gridPosition)
+          };
+
+          if (entity.hasComponent("momentum")) {
+            entity.components.momentum.dx = 0;
+            entity.components.momentum.dy = 0;
+          }
+        }
+      }
+    });
+  };
+
+  return { entitiesGrid, gameCoordsToGrid, gridCoordsToGame, update, gridWidth, gridHeight };
+};
\ No newline at end of file
diff --git a/src/systems/physics.js b/src/systems/physics.js
new file mode 100644
index 0000000..c9b6cf7
--- /dev/null
+++ b/src/systems/physics.js
@@ -0,0 +1,13 @@
+game.system.Physics = () => {
+  const update = (elapsedTime) => {
+    for (let id in game.entities) {
+      const entity = game.entities[id];
+      if (entity.hasComponent("momentum")) {
+        const {dx, dy} = entity.components.momentum;
+        entity.components.position.x += dx * elapsedTime;
+        entity.components.position.y += dy * elapsedTime;
+      }
+    }
+  }
+  return { update };
+}
\ No newline at end of file
diff --git a/src/systems/render.js b/src/systems/render.js
index c8eff4b..0a4c72d 100644
--- a/src/systems/render.js
+++ b/src/systems/render.js
@@ -1,18 +1,13 @@
-game.systems = {};
-game.systems.Render = ((graphics) => {
-  const renderEntities = (elapsedTime, entities) => {
+game.system.Render = (graphics) => {
+  const update = (elapsedTime, entities) => {
+    graphics.clear();
+
     for (let id in entities) {
       const entity = entities[id];
-      if (entity.sprite && entity.components.position && entity.components.appearance) {
-//        document.getElementById("game-canvas").getContext("2d").drawImage(game.assets.bigblue, 100, 100, 100, 100);
+      if (entity.sprite && entity.hasComponent("position") && entity.hasComponent("appearance")) {
         entity.sprite.draw(elapsedTime, {...entity.components.position, ...entity.components.appearance});
       }
     }
   }
-
-  const update = (elapsedTime) => {
-    graphics.clear();
-    renderEntities(elapsedTime, game.entities);
-  }
   return { update };
-})(game.graphics);
\ No newline at end of file
+};
\ No newline at end of file
diff --git a/src/systems/system.js b/src/systems/system.js
new file mode 100644
index 0000000..f331401
--- /dev/null
+++ b/src/systems/system.js
@@ -0,0 +1 @@
+game.system = {};
\ No newline at end of file
diff --git a/src/utils/objectEquivalence.js b/src/utils/objectEquivalence.js
new file mode 100644
index 0000000..e33dd76
--- /dev/null
+++ b/src/utils/objectEquivalence.js
@@ -0,0 +1,14 @@
+const equivalence = (obj1, obj2) => {
+  if (obj1 === null) {
+    return obj1 === null;
+  }
+  return Object.keys(obj1).every(key => {
+    if (obj2[key] === undefined) {
+      return false;
+    }
+    if (typeof obj1[key] === 'object') {
+      return equivalence(obj1[key], obj2[key]);
+    }
+    return obj1[key] === obj2[key];
+  });
+};
diff --git a/src/utils/unitizeVector.js b/src/utils/unitizeVector.js
new file mode 100644
index 0000000..6297ca8
--- /dev/null
+++ b/src/utils/unitizeVector.js
@@ -0,0 +1,11 @@
+const unitize = (vector) => {
+  // Not *technically* a unit vector, but has x,y components of |magnitude| = 1
+  Object.keys(vector).forEach((key) => {
+    if (typeof vector[key] === 'object') {
+      vector[key] = vector[key].unitize();
+    } else if (typeof vector[key] === 'number') {
+      vector[key] = (vector[key] === 0 ? 0 : vector[key] / Math.abs(vector[key]));
+    }
+  });
+  return vector;
+}
\ No newline at end of file