improve texture loading

src/js/net/minecraft/client/gui/Gui.js

@@ -110,11 +110,7 @@ window.Gui = class {
         stack.restore();
     }
 
-    static loadTexture(path, callback) {
-        let img = new Image();
-        img.src = "src/resources/" + path;
-        img.onload = callback;
-        return img;
+    static loadTexture(path) {
+        return document.textures[path];
     }
-
 }

src/js/net/minecraft/client/render/gui/FontRenderer.js

@@ -8,15 +8,14 @@ window.FontRenderer = class {
     constructor() {
         this.charWidths = [];
 
-        let scope = this;
-        this.texture = Gui.loadTexture("font.png", function () {
-            let bitMap = scope.createBitMap(scope.texture);
+        this.texture = Gui.loadTexture("font.png")
+
+        let bitMap = this.createBitMap(this.texture);
 
         // Calculate character width
         for (let i = 0; i < 128; i++) {
-                scope.charWidths[i] = scope.calculateCharacterWidthAt(bitMap, i % FontRenderer.BITMAP_SIZE, Math.floor(i / FontRenderer.BITMAP_SIZE)) + 2;
+            this.charWidths[i] = this.calculateCharacterWidthAt(bitMap, i % FontRenderer.BITMAP_SIZE, Math.floor(i / FontRenderer.BITMAP_SIZE)) + 2;
         }
-        });
     }
 
     calculateCharacterWidthAt(bitMap, indexX, indexY) {

src/start.js

@@ -37,10 +37,44 @@ function loadScripts(scripts) {
     }, Promise.resolve());
 }
 
+// Texture loader
+function loadTexture(textures) {
+    let total = textures.length;
+    let index = 0;
+
+    document.textures = [];
+
+    return textures.reduce((currentPromise, texturePath) => {
+        return currentPromise.then(() => {
+            return new Promise((resolve, reject) => {
+                // Update status message
+                updatePreStatus("Loading texture... " + index + "/" + total);
+
+                // Load texture
+                let image = new Image();
+                image.src = "src/resources/" + texturePath;
+                image.onload = () => resolve();
+                document.textures[texturePath] = image;
+
+                index++;
+            });
+        });
+    }, Promise.resolve());
+}
+
+
 function updatePreStatus(message) {
     document.getElementById("pre-status").innerText = message;
 }
 
+// Load textures
+loadTexture([
+    "font.png",
+    "gui.png",
+    "background.png",
+    "terrain.png",
+    "icons.png"
+]).then(() => {
     // Load scripts
     loadScripts([
         // Dependencies
@@ -105,3 +139,4 @@ loadScripts([
         // Start Minecraft
         window.app = new Minecraft("canvas-container");
     });
+});