Merge 58b12cc into bba0e71

uber-web · Aug 26, 2019 · 8d1786b · 8d1786b
2 parents bba0e71 + 58b12cc
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diff --git a/modules/core/docs/api-reference/matrix4.md b/modules/core/docs/api-reference/matrix4.md
@@ -326,6 +326,13 @@ Transforms
 
 ### transformByMatrix2(vector : Number[4]) : Number[4]
 
+### getRotation([result : Number[16]]) : Number[16]
+
+Returns rotation matrix (4 * 4).
+
+### getRotationMatrix3([result : Number[9]]) : Number[9]
+
+Returns rotation matrix (3 * 3).
 
 ## Remarks
 

diff --git a/modules/core/src/classes/matrix4.js b/modules/core/src/classes/matrix4.js
@@ -365,6 +365,25 @@ export default class Matrix4 extends Matrix {
     return result;
   }
 
+  getRotationMatrix3(result = [-0, -0, -0, -0, -0, -0, -0, -0, -0], scaleResult = null) {
+    const scale = this.getScale(scaleResult || [-0, -0, -0]);
+
+    const inverseScale0 = 1 / scale[0];
+    const inverseScale1 = 1 / scale[1];
+    const inverseScale2 = 1 / scale[2];
+
+    result[0] = this[0] * inverseScale0;
+    result[1] = this[1] * inverseScale1;
+    result[2] = this[2] * inverseScale2;
+    result[3] = this[4] * inverseScale0;
+    result[4] = this[5] * inverseScale1;
+    result[5] = this[6] * inverseScale2;
+    result[6] = this[8] * inverseScale0;
+    result[7] = this[9] * inverseScale1;
+    result[8] = this[10] * inverseScale2;
+    return result;
+  }
+
   // Modifiers
 
   transpose() {

diff --git a/modules/core/test/classes/matrix4.bench.js b/modules/core/test/classes/matrix4.bench.js
@@ -127,7 +127,8 @@ export default function matrix4Bench(suite, addReferenceBenchmarks) {
     .add('Matrix4#determinant()', () => matrix4.determinant())
     .add('Matrix4#getScale()', () => matrix4.getScale())
     .add('Matrix4#getTranslation()', () => matrix4.getTranslation())
-    .add('Matrix4#getRotation()', () => matrix4.getRotation());
+    .add('Matrix4#getRotation()', () => matrix4.getRotation())
+    .add('Matrix4#getRotationMatrix3()', () => matrix4.getRotationMatrix3());
 
   suite
     .group('@math.gl/core: Matrix4 operations')

diff --git a/modules/core/test/classes/matrix4.spec.js b/modules/core/test/classes/matrix4.spec.js
@@ -202,6 +202,26 @@ test('Matrix4#getRotation', t => {
   t.end();
 });
 
+test('Matrix4#getRotationMatrix3', t => {
+  const INPUT = INDICES_MATRIX;
+  const RESULT = [
+    0.2672612419124244,
+    0.19069251784911848,
+    0.17263060129453078,
+    1.3363062095621219,
+    0.5720775535473555,
+    0.4028047363539052,
+    2.4053511772118195,
+    0.9534625892455924,
+    0.6329788714132796
+  ];
+
+  const m = new Matrix4(INPUT).getRotationMatrix3([...INDICES_MATRIX.slice(0, 9)]);
+  tapeEquals(t, m, RESULT, 'getRotationMatrix3 gave the right result');
+
+  t.end();
+});
+
 test('Matrix4#getTranslation', t => {
   const INPUT = INDICES_MATRIX;
   const RESULT = [13, 14, 15];