From c4c72e45d2b719bc86520b56249ef4eedaa9568c Mon Sep 17 00:00:00 2001
From: singlecoder <z18511751272@gmail.com>
Date: Tue, 8 Jun 2021 20:32:25 +0800
Subject: [PATCH] feat: add ortho control for camera (#278)

---
 packages/controls/src/OrthoControl.ts        | 127 +++++++++++++++++++
 packages/controls/src/index.ts               |   1 +
 packages/controls/tests/OrthoControl.test.ts |  39 ++++++
 3 files changed, 167 insertions(+)
 create mode 100644 packages/controls/src/OrthoControl.ts
 create mode 100644 packages/controls/tests/OrthoControl.test.ts

diff --git a/packages/controls/src/OrthoControl.ts b/packages/controls/src/OrthoControl.ts
new file mode 100644
index 0000000000..cdc8e0ed70
--- /dev/null
+++ b/packages/controls/src/OrthoControl.ts
@@ -0,0 +1,127 @@
+import { Camera, Entity, Logger, Script, Vector2, Vector3 } from "oasis-engine";
+
+/**
+ * The camera's 2D controller, can zoom and pan.
+ */
+export class OrthoControl extends Script {
+  cameraEntity: Entity;
+  camera: Camera;
+
+  private _zoomSpeed: number = 1.0;
+  private _zoomScale: number = 1.0;
+  private _zoomScaleUnit: number = 25.0;
+  private _zoomMinSize: number = 0.0;
+  private _zoomMaxSize: number = Infinity;
+  private _isPanStart: boolean = false;
+  private _panStartPos: Vector3 = new Vector3();
+  private _panStart: Vector2 = new Vector2();
+  private _panEnd: Vector2 = new Vector2();
+  private _panDelta: Vector2 = new Vector2();
+
+  /**
+   * The zoom speed.
+   */
+  get zoomSpeed(): number {
+    return this._zoomSpeed;
+  }
+
+  set zoomSpeed(value: number) {
+    this._zoomSpeed = value;
+  }
+
+  constructor(entity: Entity) {
+    super(entity);
+
+    this.cameraEntity = entity;
+    this.camera = entity.getComponent(Camera);
+  }
+
+  onUpdate(dt: number): void {
+    if (this._zoomScale !== 1) {
+      const { camera } = this;
+      const sizeDiff = this._zoomScaleUnit * (this._zoomScale - 1);
+      const size = camera.orthographicSize + sizeDiff;
+      camera.orthographicSize = Math.max(this._zoomMinSize, Math.min(this._zoomMaxSize, size));
+      this._zoomScale = 1;
+    }
+
+    if (this._isPanStart) {
+      const { _panStart: panStart, _panEnd: panEnd } = this;
+      const panDelta = this._panDelta;
+      Vector2.subtract(panEnd, panStart, panDelta);
+      if (panDelta.x === 0 && panDelta.y === 0) {
+        return ;
+      }
+      this._handlePan();
+      panEnd.cloneTo(panStart);
+    }
+  }
+
+  /**
+   * Zoom in.
+   */
+  zoomIn(): void {
+    this._zoomScale *= this._getZoomScale();
+  }
+
+  /**
+   * Zoom out.
+   */
+  zoomOut(): void {
+    this._zoomScale /= this._getZoomScale();
+  }
+
+  /**
+   * Start pan.
+   * @param x - The x-axis coordinate (unit: pixel)
+   * @param y - The y-axis coordinate (unit: pixel)
+   */
+  panStart(x: number, y: number): void {
+    if (!this.enabled) return;
+
+    this.cameraEntity.transform.position.cloneTo(this._panStartPos);
+    this._panStart.setValue(x, y);
+    this._panEnd.setValue(x, y);
+    this._isPanStart = true;
+  }
+
+  /**
+   * Panning.
+   * @param x - The x-axis coordinate (unit: pixel)
+   * @param y - The y-axis coordinate (unit: pixel)
+   *
+   * @remarks Make sure to call panStart before calling panMove.
+   */
+  panMove(x: number, y: number): void {
+    if (!this.enabled) return;
+    if (!this._isPanStart) {
+      Logger.warn("Make sure to call panStart before calling panMove");
+    }
+    this._panEnd.setValue(x, y);
+  }
+
+  /**
+   * End pan.
+   */
+  panEnd(): void {
+    if (!this.enabled) return;
+    this._isPanStart = false;
+  }
+
+  private _getZoomScale(): number {
+    return Math.pow(0.95, this.zoomSpeed);
+  }
+
+  private _handlePan(): void {
+    const { width, height } = this.engine.canvas;
+    const { x, y } = this._panDelta;
+    const { camera } = this;
+    const doubleOrthographicSize = camera.orthographicSize * 4;
+    const width3D = doubleOrthographicSize * camera.aspectRatio;
+    const height3D = doubleOrthographicSize;
+    const pos = this._panStartPos;
+    pos.x -= (x * width3D) / width;
+    pos.y += (y * height3D) / height;
+    this.cameraEntity.transform.position = pos;
+  }
+}
diff --git a/packages/controls/src/index.ts b/packages/controls/src/index.ts
index fb51fff610..16f610636c 100644
--- a/packages/controls/src/index.ts
+++ b/packages/controls/src/index.ts
@@ -1,2 +1,3 @@
 export { FreeControl } from "./FreeControl";
 export { OrbitControl } from "./OrbitControl";
+export { OrthoControl } from "./OrthoControl";
diff --git a/packages/controls/tests/OrthoControl.test.ts b/packages/controls/tests/OrthoControl.test.ts
new file mode 100644
index 0000000000..eed0f2486b
--- /dev/null
+++ b/packages/controls/tests/OrthoControl.test.ts
@@ -0,0 +1,39 @@
+import { Camera, Entity, WebGLEngine } from "oasis-engine";
+import { OrthoControl } from "../src/OrthoControl";
+
+const canvasDOM = document.createElement("canvas");
+canvasDOM.width = 1024;
+canvasDOM.height = 1024;
+
+describe(" Ortho Control", () => {
+  let entity: Entity;
+  let camera: Camera;
+  let cameraControl: OrthoControl;
+
+  beforeAll(() => {
+    const engine = new WebGLEngine(canvasDOM);
+    entity = engine.sceneManager.activeScene.createRootEntity();
+    camera = entity.addComponent(Camera);
+    cameraControl = entity.addComponent(OrthoControl);
+  });
+
+  it("test zoom", () => {
+    cameraControl.zoomIn();
+    cameraControl.onUpdate(0);
+    expect(camera.orthographicSize).toEqual(8.749999999999998);
+    cameraControl.zoomOut();
+    cameraControl.onUpdate(0);
+    expect(camera.orthographicSize).toEqual(10.065789473684207);
+  });
+
+  it("test pan", () => {
+    cameraControl.panStart(0, 0);
+    cameraControl.panMove(2, 0);
+    cameraControl.onUpdate(0);
+    cameraControl.panEnd();
+
+    const pos = entity.transform.position;
+    expect(pos.x).toEqual(-0.07863898026315787);
+    expect(pos.y).toEqual(0);
+  });
+});