port rotate from gl-matrix for vec2, vec3. fixes #23

greggman · Mar 22, 2024 · b89fa2b · b89fa2b
1 parent 4e0a639
commit b89fa2b
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diff --git a/src/vec2-impl.ts b/src/vec2-impl.ts
@@ -644,3 +644,26 @@ export function transformMat3(v: Vec2, m: Mat3, dst?: Vec2): Vec2 {
   return dst;
 }
 
+/**
+ * Rotate a 2D vector
+ *
+ * @param a The vec2 point to rotate
+ * @param b The origin of the rotation
+ * @param rad The angle of rotation in radians
+ * @returns the rotated vector
+ */
+export function rotate(a: Vec2, b: Vec2, rad: number, dst?: Vec2) {
+  dst = dst || new VecType(2);
+
+  // Translate point to the origin
+  const p0 = a[0] - b[0];
+  const p1 = a[1] - b[1];
+  const sinC = Math.sin(rad);
+  const cosC = Math.cos(rad);
+
+  //perform rotation and translate to correct position
+  dst[0] = p0 * cosC - p1 * sinC + b[0];
+  dst[1] = p0 * sinC + p1 * cosC + b[1];
+
+  return dst;
+}
diff --git a/src/vec3-impl.ts b/src/vec3-impl.ts
@@ -786,4 +786,100 @@ export function getScaling(m: Mat4, dst: Vec3) {
     dst[1] = Math.sqrt(yx * yx + yy * yy + yz * yz);
     dst[2] = Math.sqrt(zx * zx + zy * zy + zz * zz);
     return dst;
-}
+}
+
+/**
+ * Rotate a 3D vector around the x-axis
+ *
+ * @param {ReadonlyVec3} a The vec3 point to rotate
+ * @param {ReadonlyVec3} b The origin of the rotation
+ * @param {Number} rad The angle of rotation in radians
+ * @param dst - The vector to set. If not passed a new one is created.
+ * @returns the rotated vector
+ */
+export function rotateX(a: Vec3, b: Vec3, rad: number, dst?: Vec3) {
+  dst = dst || new VecType(3);
+  const p = [];
+  const r = [];
+
+  //Translate point to the origin
+  p[0] = a[0] - b[0];
+  p[1] = a[1] - b[1];
+  p[2] = a[2] - b[2];
+
+  //perform rotation
+  r[0] = p[0];
+  r[1] = p[1] * Math.cos(rad) - p[2] * Math.sin(rad);
+  r[2] = p[1] * Math.sin(rad) + p[2] * Math.cos(rad);
+
+  //translate to correct position
+  dst[0] = r[0] + b[0];
+  dst[1] = r[1] + b[1];
+  dst[2] = r[2] + b[2];
+
+  return dst;
+}
+
+/**
+ * Rotate a 3D vector around the y-axis
+ *
+ * @param {ReadonlyVec3} a The vec3 point to rotate
+ * @param {ReadonlyVec3} b The origin of the rotation
+ * @param {Number} rad The angle of rotation in radians
+ * @param dst - The vector to set. If not passed a new one is created.
+ * @returns the rotated vector
+ */
+export function rotateY(a: Vec3, b: Vec3, rad: number, dst?: Vec3) {
+  dst = dst || new VecType(3);
+  const p = [];
+  const r = [];
+
+  // translate point to the origin
+  p[0] = a[0] - b[0];
+  p[1] = a[1] - b[1];
+  p[2] = a[2] - b[2];
+
+  // perform rotation
+  r[0] = p[2] * Math.sin(rad) + p[0] * Math.cos(rad);
+  r[1] = p[1];
+  r[2] = p[2] * Math.cos(rad) - p[0] * Math.sin(rad);
+
+  // translate to correct position
+  dst[0] = r[0] + b[0];
+  dst[1] = r[1] + b[1];
+  dst[2] = r[2] + b[2];
+
+  return dst;
+}
+
+/**
+ * Rotate a 3D vector around the z-axis
+ *
+ * @param {ReadonlyVec3} a The vec3 point to rotate
+ * @param {ReadonlyVec3} b The origin of the rotation
+ * @param {Number} rad The angle of rotation in radians
+ * @param dst - The vector to set. If not passed a new one is created.
+ * @returns {vec3} out
+ */
+export function rotateZ(a: Vec3, b: Vec3, rad: number, dst?: Vec3) {
+  dst = dst || new VecType(3);
+  const p = [];
+  const r = [];
+
+  // translate point to the origin
+  p[0] = a[0] - b[0];
+  p[1] = a[1] - b[1];
+  p[2] = a[2] - b[2];
+
+  // perform rotation
+  r[0] = p[0] * Math.cos(rad) - p[1] * Math.sin(rad);
+  r[1] = p[0] * Math.sin(rad) + p[1] * Math.cos(rad);
+  r[2] = p[2];
+
+  // translate to correct position
+  dst[0] = r[0] + b[0];
+  dst[1] = r[1] + b[1];
+  dst[2] = r[2] + b[2];
+
+  return dst;
+}
diff --git a/test/tests/vec2-test.js b/test/tests/vec2-test.js
@@ -471,5 +471,30 @@ describe('vec2', () => {
   check(Float32Array);
   check(Float64Array);
 
+  describe('rotate', function() {
+    describe('rotation around world origin [0, 0, 0]', function() {
+      let vecA, vecB, result;
+      beforeEach(function () {
+        vecA = [0, 1];
+        vecB = [0, 0];
+        result = vec2.rotate(vecA, vecB, Math.PI);
+      });
+      it("should return the rotated vector", function () {
+        assertEqualApproximately(result, [0, -1]);
+      });
+    });
+    describe('rotation around an arbitrary origin', function () {
+      let vecA, vecB, result;
+      beforeEach(function () {
+        vecA = [6, -5];
+        vecB = [0, -5];
+        result = vec2.rotate(vecA, vecB, Math.PI);
+      });
+      it("should return the rotated vector", function () {
+        assertEqualApproximately(result, [-6, -5]);
+      });
+    });
+  });
+
 });
 
diff --git a/test/tests/vec3-test.js b/test/tests/vec3-test.js
@@ -480,5 +480,76 @@ describe('vec3', () => {
   check(Float32Array);
   check(Float64Array);
 
+  let vecA, vecB, result;
+
+  describe('rotateX', function () {
+    describe('rotation around world origin [0, 0, 0]', function () {
+      beforeEach(function () {
+        vecA = [0, 1, 0];
+        vecB = [0, 0, 0];
+        result = vec3.rotateX(vecA, vecB, Math.PI);
+      });
+      it("should return the rotated vector", function () {
+        assertEqualApproximately(result, [0, -1, 0]);
+      });
+    });
+
+    describe('rotation around an arbitrary origin', function () {
+      beforeEach(function () {
+        vecA = [2, 7, 0];
+        vecB = [2, 5, 0];
+        result = vec3.rotateX(vecA, vecB, Math.PI);
+      });
+      it("should return the rotated vector", function () {
+        assertEqualApproximately(result, [2, 3, 0]);
+      });
+    });
+  });
+
+  describe('rotateY', function () {
+    describe('rotation around world origin [0, 0, 0]', function () {
+        beforeEach(function() {
+          vecA = [1, 0, 0];
+          vecB = [0, 0, 0];
+          result = vec3.rotateY(vecA, vecB, Math.PI);
+        });
+        it("should return the rotated vector", function () {
+          assertEqualApproximately(result, [-1, 0, 0]);
+        });
+    });
+    describe('rotation around an arbitrary origin', function () {
+        beforeEach(function () {
+          vecA = [-2, 3, 10];
+          vecB = [-4, 3, 10];
+          result = vec3.rotateY(vecA, vecB, Math.PI);
+        });
+        it("should return the rotated vector", function () {
+          assertEqualApproximately(result, [-6, 3, 10]);
+        });
+    });
+  });
+
+  describe('rotateZ', function () {
+    describe('rotation around world origin [0, 0, 0]', function () {
+        beforeEach(function () {
+          vecA = [0, 1, 0];
+          vecB = [0, 0, 0];
+          result = vec3.rotateZ(vecA, vecB, Math.PI);
+        });
+        it("should return the rotated vector", function () {
+          assertEqualApproximately(result, [0, -1, 0]);
+        });
+    });
+    describe('rotation around an arbitrary origin', function () {
+        beforeEach(function () {
+          vecA = [0, 6, -5];
+          vecB = [0, 0, -5];
+          result = vec3.rotateZ(vecA, vecB, Math.PI);
+        });
+        it("should return the rotated vector", function () {
+          assertEqualApproximately(result, [0, -6, -5]);
+        });
+    });
+  });
 });