init

main.ts

@@ -1 +1,92 @@
-
+//% block="Split Screen"
+//% icon="\uf030"
+//% color="#bd7844"
+namespace splitScreen {
+    let rowBuff: Buffer;
+    class SplitScreenState {
+        fakeCamera: scene.Camera;
+        fakeScreen: ScreenImage;
+        renderable: scene.Renderable;
+        isRendering: boolean;
+        realScreen: ScreenImage;
+        realCamera: scene.Camera;
+
+        constructor() {
+            this.fakeCamera = new scene.Camera();
+            this.fakeScreen = image.create(screen.width, screen.height) as ScreenImage;
+            this.isRendering = false;
+
+
+            this.renderable = scene.createRenderable(99, () => {
+                if (!this.fakeCamera.sprite) return;
+
+                if (!this.isRendering) {
+                    this.fakeCamera.update();
+                    this.realScreen = screen;
+                    this.realCamera = game.currentScene().camera
+                    screen = this.fakeScreen
+                    game.currentScene().camera = this.fakeCamera
+
+                    this.isRendering = true;
+                    // black magic
+                    game.currentScene().flags &= ~(scene.Flag.IsRendering)
+                    game.currentScene().render();
+                    this.isRendering = false;
+
+                    screen = this.realScreen;
+                    game.currentScene().camera = this.realCamera;
+                    this.realScreen.fillRect(79, 0, 2, 120, 15)
+                }
+                else {
+                    const tm = game.currentScene().tileMap;
+
+                    const realOffsetX = Math.clamp(0, tm.areaWidth(), this.realCamera.sprite.x - 40);
+                    shiftScreen(this.realScreen, Math.min(realOffsetX - this.realCamera.offsetX, 80));
+
+                    const fakeOffsetX = Math.clamp(0, tm.areaWidth(), this.fakeCamera.sprite.x - 40);
+
+                    shiftScreen(this.fakeScreen, Math.min(fakeOffsetX - this.fakeCamera.offsetX, 80));
+                    this.realScreen.drawImage(this.fakeScreen, 80, 0);
+                }
+            })
+        }
+    }
+
+    let stateStack: SplitScreenState[];
+
+    /**
+     * Adds a splitscreen camera to a game
+     */
+    //% blockId="splitscreencamerafollowsprite"
+    //% block="split screen camera follow $sprite"
+    export function splitScreenCameraFollow(sprite: Sprite) {
+        state().fakeCamera.sprite = sprite;
+    }
+
+    function init() {
+        if (stateStack) return;
+        stateStack = [new SplitScreenState()];
+        rowBuff = control.createBuffer(screen.height);
+
+        game.addScenePushHandler(() => {
+            stateStack.push(new SplitScreenState())
+        })
+
+        game.addScenePopHandler(() => {
+            stateStack.pop();
+            if (stateStack.length === 0) stateStack.push(new SplitScreenState())
+        })
+    }
+
+    function state() {
+        init();
+        return stateStack[stateStack.length - 1];
+    }
+
+    function shiftScreen(target: Image, numPixels: number) {
+        for (let x = 0; x < target.width - numPixels; x++) {
+            target.getRows(x + numPixels, rowBuff)
+            target.setRows(x, rowBuff)
+        }
+    }
+}

pxt.json

@@ -1,5 +1,5 @@
 {
-    "name": "Untitled",
+    "name": "arcade-split-screen",
     "description": "",
     "dependencies": {
         "device": "*"