add 3d rotation to mat3

rotateX
rotationX
rotateY
rotationY
rotateZ
rotationZ

Author: greggman

src/mat3-impl.ts

@@ -661,6 +661,135 @@ function rotate<T extends Mat3Arg = MatType>(m: Mat3Arg, angleInRadians: number,
   return newDst;
 }
 
+/**
+ * Creates a 3-by-3 matrix which rotates around the x-axis by the given angle.
+ * @param angleInRadians - The angle by which to rotate (in radians).
+ * @param dst - matrix to hold result. If not passed a new one is created.
+ * @returns The rotation matrix.
+ */
+function rotationX<T extends Mat3Arg = MatType>(angleInRadians: number, dst?: T) {
+  const newDst = (dst ?? new Ctor(12)) as T;
+
+  const c = Math.cos(angleInRadians);
+  const s = Math.sin(angleInRadians);
+
+  newDst[ 0] = 1;  newDst[ 1] =  0;  newDst[ 2] = 0;
+  newDst[ 4] = 0;  newDst[ 5] =  c;  newDst[ 6] = s;
+  newDst[ 8] = 0;  newDst[ 9] = -s;  newDst[10] = c;
+
+  return newDst;
+}
+
+/**
+ * Rotates the given 3-by-3 matrix around the x-axis by the given
+ * angle.
+ * @param m - The matrix.
+ * @param angleInRadians - The angle by which to rotate (in radians).
+ * @param dst - matrix to hold result. If not passed a new one is created.
+ * @returns The rotated matrix.
+ */
+function rotateX<T extends Mat3Arg = MatType>(m: Mat3Arg, angleInRadians: number, dst?: T) {
+  const newDst = (dst ?? new Ctor(12)) as T;
+
+  const m10 = m[4];
+  const m11 = m[5];
+  const m12 = m[6];
+  const m20 = m[8];
+  const m21 = m[9];
+  const m22 = m[10];
+
+  const c = Math.cos(angleInRadians);
+  const s = Math.sin(angleInRadians);
+
+  newDst[4]  = c * m10 + s * m20;
+  newDst[5]  = c * m11 + s * m21;
+  newDst[6]  = c * m12 + s * m22;
+  newDst[8]  = c * m20 - s * m10;
+  newDst[9]  = c * m21 - s * m11;
+  newDst[10] = c * m22 - s * m12;
+
+  if (m !== newDst) {
+    newDst[ 0] = m[ 0];
+    newDst[ 1] = m[ 1];
+    newDst[ 2] = m[ 2];
+  }
+
+  return newDst;
+}
+
+/**
+ * Creates a 3-by-3 matrix which rotates around the y-axis by the given angle.
+ * @param angleInRadians - The angle by which to rotate (in radians).
+ * @param dst - matrix to hold result. If not passed a new one is created.
+ * @returns The rotation matrix.
+ */
+function rotationY<T extends Mat3Arg = MatType>(angleInRadians: number, dst?: T) {
+  const newDst = (dst ?? new Ctor(12)) as T;
+
+  const c = Math.cos(angleInRadians);
+  const s = Math.sin(angleInRadians);
+
+  newDst[ 0] = c;  newDst[ 1] = 0;  newDst[ 2] = -s;
+  newDst[ 4] = 0;  newDst[ 5] = 1;  newDst[ 6] =  0;
+  newDst[ 8] = s;  newDst[ 9] = 0;  newDst[10] =  c;
+
+  return newDst;
+}
+
+/**
+ * Rotates the given 3-by-3 matrix around the y-axis by the given
+ * angle.
+ * @param m - The matrix.
+ * @param angleInRadians - The angle by which to rotate (in radians).
+ * @param dst - matrix to hold result. If not passed a new one is created.
+ * @returns The rotated matrix.
+ */
+function rotateY<T extends Mat3Arg = MatType>(m: Mat3Arg, angleInRadians: number, dst?: T) {
+  const newDst = (dst ?? new Ctor(12)) as T;
+
+  const m00 = m[0 * 4 + 0];
+  const m01 = m[0 * 4 + 1];
+  const m02 = m[0 * 4 + 2];
+  const m20 = m[2 * 4 + 0];
+  const m21 = m[2 * 4 + 1];
+  const m22 = m[2 * 4 + 2];
+  const c = Math.cos(angleInRadians);
+  const s = Math.sin(angleInRadians);
+
+  newDst[ 0] = c * m00 - s * m20;
+  newDst[ 1] = c * m01 - s * m21;
+  newDst[ 2] = c * m02 - s * m22;
+  newDst[ 8] = c * m20 + s * m00;
+  newDst[ 9] = c * m21 + s * m01;
+  newDst[10] = c * m22 + s * m02;
+
+  if (m !== newDst) {
+    newDst[ 4] = m[ 4];
+    newDst[ 5] = m[ 5];
+    newDst[ 6] = m[ 6];
+  }
+
+  return newDst;
+}
+
+/**
+ * Creates a 3-by-3 matrix which rotates around the z-axis by the given angle.
+ * @param angleInRadians - The angle by which to rotate (in radians).
+ * @param dst - matrix to hold result. If not passed a new one is created.
+ * @returns The rotation matrix.
+ */
+const rotationZ = rotation;
+
+/**
+ * Rotates the given 3-by-3 matrix around the z-axis by the given
+ * angle.
+ * @param m - The matrix.
+ * @param angleInRadians - The angle by which to rotate (in radians).
+ * @param dst - matrix to hold result. If not passed a new one is created.
+ * @returns The rotated matrix.
+ */
+const rotateZ = rotate;
+
 /**
  * Creates a 3-by-3 matrix which scales in each dimension by an amount given by
  * the corresponding entry in the given vector; assumes the vector has three
@@ -784,6 +913,12 @@ return {
   translate,
   rotation,
   rotate,
+  rotationX,
+  rotateX,
+  rotationY,
+  rotateY,
+  rotationZ,
+  rotateZ,
   scaling,
   scale,
   uniformScaling,

test/tests/mat3-test.js

@@ -448,6 +448,78 @@ function check(mat3, Type) {
       }, expected);
     });
 
+    it('should make rotationX matrix', () => {
+      const angle = 1.23;
+      const c = Math.cos(angle);
+      const s = Math.sin(angle);
+      const expected = [
+         1,  0, 0, 0,
+         0,  c, s, 0,
+         0, -s, c, 0,
+      ];
+      testMat3WithAndWithoutDest((newDst) => {
+        return mat3.rotationX(angle, newDst);
+      }, expected);
+    });
+
+    it('should rotateX', () => {
+      const angle = 1.23;
+      // switch to Array type to keep precision high for expected
+      const expected = mat3n.multiply(m, mat3.rotationX(angle));
+
+      testMat3WithAndWithoutDest((newDst) => {
+        return mat3.rotateX(m, angle, newDst);
+      }, expected);
+    });
+
+    it('should make rotationY matrix', () => {
+      const angle = 1.23;
+      const c = Math.cos(angle);
+      const s = Math.sin(angle);
+      const expected = [
+         c, 0, -s, 0,
+         0, 1,  0, 0,
+         s, 0,  c, 0,
+      ];
+      testMat3WithAndWithoutDest((newDst) => {
+        return mat3.rotationY(angle, newDst);
+      }, expected);
+    });
+
+    it('should rotateY', () => {
+      const angle = 1.23;
+      // switch to Array type to keep precision high for expected
+      const expected = mat3n.multiply(m, mat3.rotationY(angle));
+
+      testMat3WithAndWithoutDest((newDst) => {
+        return mat3.rotateY(m, angle, newDst);
+      }, expected);
+    });
+
+    it('should make rotationZ matrix', () => {
+      const angle = 1.23;
+      const c = Math.cos(angle);
+      const s = Math.sin(angle);
+      const expected = [
+         c, s, 0, 0,
+        -s, c, 0, 0,
+         0, 0, 1, 0,
+      ];
+      testMat3WithAndWithoutDest((newDst) => {
+        return mat3.rotationZ(angle, newDst);
+      }, expected);
+    });
+
+    it('should rotateZ', () => {
+      const angle = 1.23;
+      // switch to Array type to keep precision high for expected
+      const expected = mat3n.multiply(m, mat3.rotationZ(angle));
+
+      testMat3WithAndWithoutDest((newDst) => {
+        return mat3.rotateZ(m, angle, newDst);
+      }, expected);
+    });
+
     it('should make scaling matrix', () => {
       const expected = [
         2, 0, 0, 0,