From 6582eb990c94ac9c7013dda8390d88dfe7ef946b Mon Sep 17 00:00:00 2001
From: Steve Ruiz <steveruizok@gmail.com>
Date: Sun, 23 May 2021 09:30:20 +0100
Subject: [PATCH] improve rotation

---
 lib/shape-utils/ellipse.tsx      | 21 +++++++++++++++------
 state/sessions/rotate-session.ts |  5 +++--
 utils/bounds.ts                  | 22 ++++++++++++++++++++++
 utils/utils.ts                   |  9 +++++++++
 4 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/lib/shape-utils/ellipse.tsx b/lib/shape-utils/ellipse.tsx
index 556b1636f..ce298ed59 100644
--- a/lib/shape-utils/ellipse.tsx
+++ b/lib/shape-utils/ellipse.tsx
@@ -2,7 +2,7 @@ import { v4 as uuid } from "uuid"
 import * as vec from "utils/vec"
 import { EllipseShape, ShapeType } from "types"
 import { registerShapeUtils } from "./index"
-import { boundsContained } from "utils/bounds"
+import { boundsContained, getRotatedEllipseBounds } from "utils/bounds"
 import { intersectEllipseBounds } from "utils/intersections"
 import { pointInEllipse } from "utils/hitTests"
 import {
@@ -47,8 +47,8 @@ const ellipse = registerShapeUtils<EllipseShape>({
 
       const bounds = {
         minX: 0,
-        maxX: radiusX * 2,
         minY: 0,
+        maxX: radiusX * 2,
         maxY: radiusY * 2,
         width: radiusX * 2,
         height: radiusY * 2,
@@ -61,7 +61,13 @@ const ellipse = registerShapeUtils<EllipseShape>({
   },
 
   getRotatedBounds(shape) {
-    return getBoundsFromPoints(getRotatedCorners(shape))
+    return getRotatedEllipseBounds(
+      shape.point[0],
+      shape.point[1],
+      shape.radiusX,
+      shape.radiusY,
+      shape.rotation
+    )
   },
 
   getCenter(shape) {
@@ -79,8 +85,6 @@ const ellipse = registerShapeUtils<EllipseShape>({
   },
 
   hitTestBounds(this, shape, brushBounds) {
-    // TODO: Account for rotation
-
     const shapeBounds = this.getBounds(shape)
 
     return (
@@ -108,11 +112,16 @@ const ellipse = registerShapeUtils<EllipseShape>({
     return shape
   },
 
-  transform(shape, bounds) {
+  transform(shape, bounds, { scaleX, scaleY, initialShape }) {
     shape.point = [bounds.minX, bounds.minY]
     shape.radiusX = bounds.width / 2
     shape.radiusY = bounds.height / 2
 
+    shape.rotation =
+      (scaleX < 0 && scaleY >= 0) || (scaleY < 0 && scaleX >= 0)
+        ? -initialShape.rotation
+        : initialShape.rotation
+
     return shape
   },
 
diff --git a/state/sessions/rotate-session.ts b/state/sessions/rotate-session.ts
index 03f2dab85..10b03cad3 100644
--- a/state/sessions/rotate-session.ts
+++ b/state/sessions/rotate-session.ts
@@ -4,6 +4,7 @@ import BaseSession from "./base-session"
 import commands from "state/commands"
 import { current } from "immer"
 import {
+  clampToRotationToSegments,
   getBoundsCenter,
   getCommonBounds,
   getPage,
@@ -31,10 +32,10 @@ export default class RotateSession extends BaseSession {
     const a1 = vec.angle(boundsCenter, this.origin)
     const a2 = vec.angle(boundsCenter, point)
 
-    let rot = (PI2 + (a2 - a1)) % PI2
+    let rot = a2 - a1
 
     if (isLocked) {
-      rot = Math.floor((rot + Math.PI / 8) / (Math.PI / 4)) * (Math.PI / 4)
+      rot = clampToRotationToSegments(rot, 24)
     }
 
     data.boundsRotation = (PI2 + (this.snapshot.boundsRotation + rot)) % PI2
diff --git a/utils/bounds.ts b/utils/bounds.ts
index 5cd50316f..9fccefa1b 100644
--- a/utils/bounds.ts
+++ b/utils/bounds.ts
@@ -82,3 +82,25 @@ export function boundsAreEqual(a: Bounds, b: Bounds) {
 export function pointInBounds(A: number[], b: Bounds) {
   return !(A[0] < b.minX || A[0] > b.maxX || A[1] < b.minY || A[1] > b.maxY)
 }
+
+export function getRotatedEllipseBounds(
+  x: number,
+  y: number,
+  rx: number,
+  ry: number,
+  rotation: number
+) {
+  const c = Math.cos(rotation)
+  const s = Math.sin(rotation)
+  const w = Math.hypot(rx * c, ry * s)
+  const h = Math.hypot(rx * s, ry * c)
+
+  return {
+    minX: x + rx - w,
+    minY: y + ry - h,
+    maxX: x + rx + w,
+    maxY: y + ry + h,
+    width: w * 2,
+    height: h * 2,
+  }
+}
diff --git a/utils/utils.ts b/utils/utils.ts
index e2500db2b..2f7c0089b 100644
--- a/utils/utils.ts
+++ b/utils/utils.ts
@@ -1366,3 +1366,12 @@ export function getShapeBounds(shape: Shape) {
 export function getBoundsCenter(bounds: Bounds) {
   return [bounds.minX + bounds.width / 2, bounds.minY + bounds.height / 2]
 }
+
+export function clampRadians(r: number) {
+  return (Math.PI * 2 + r) % (Math.PI * 2)
+}
+
+export function clampToRotationToSegments(r: number, segments: number) {
+  const seg = (Math.PI * 2) / segments
+  return Math.floor((clampRadians(r) + seg / 2) / seg) * seg
+}