object controls movement helper

src/mol-canvas3d/controls/object.ts

@@ -0,0 +1,59 @@
+/**
+ * Copyright (c) 2020 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author Alexander Rose <alexander.rose@weirdbyte.de>
+ */
+
+import { Vec2, Vec3 } from '../../mol-math/linear-algebra';
+import { Camera } from '../camera';
+import { Viewport } from '../camera/util';
+
+export namespace ObjectControls {
+    function mouseOnScreen(out: Vec2, page: Vec2, viewport: Viewport) {
+        return Vec2.set(
+            out,
+            (page[0] - viewport.x) / viewport.width,
+            (page[1] - viewport.y) / viewport.height
+        );
+    }
+
+    const panMouseChange = Vec2();
+    const panObjUp = Vec3();
+    const panOffset = Vec3();
+    const eye = Vec3();
+    const panStart = Vec2();
+    const panEnd = Vec2();
+
+    const target = Vec3();
+
+    /**
+     * Get vector for movement in camera projection plane:
+     * `pageStart` and `pageEnd` are 2d window coordinates;
+     * `ref` defines the plane depth, if not given `camera.target` is used
+     */
+    export function panDirection(out: Vec3, pageStart: Vec2, pageEnd: Vec2, camera: Camera, ref?: Vec3) {
+        mouseOnScreen(panStart, pageStart, camera.viewport);
+        mouseOnScreen(panEnd, pageEnd, camera.viewport);
+        Vec2.sub(panMouseChange, Vec2.copy(panMouseChange, panEnd), panStart);
+        Vec3.sub(eye, camera.position, camera.target);
+
+        if (!ref || camera.state.mode === 'orthographic') Vec3.copy(target, camera.target);
+        else Vec3.projectPointOnVector(target, ref, eye, camera.position);
+
+        const dist = Vec3.distance(camera.position, target);
+        const height = 2 * Math.tan(camera.state.fov / 2) * dist;
+        const zoom = camera.viewport.height / height;
+
+        const dpr = window.devicePixelRatio;
+        panMouseChange[0] *= (1 / zoom) * camera.viewport.width * dpr;
+        panMouseChange[1] *= (1 / zoom) * camera.viewport.height * dpr;
+
+        Vec3.cross(panOffset, Vec3.copy(panOffset, eye), camera.up);
+        Vec3.setMagnitude(panOffset, panOffset, panMouseChange[0]);
+
+        Vec3.setMagnitude(panObjUp, camera.up, panMouseChange[1]);
+        Vec3.add(panOffset, panOffset, panObjUp);
+
+        return Vec3.negate(out, panOffset);
+    }
+}