quat2 implementation #231

stefnotch · 2016-11-10T17:05:59Z

I implemented dual quaternions, which are extremely useful for gpu skinning. CryEngine uses them!
Dual quaternions are very similar to matrices. They represent a rotation and translation using 2 quaternions.

Pros:

+They only use 8 floats (rotation, translation) instead of 16 floats.
+They do not drift over time and do not introduce unwanted scaling and shearing.
+Interpolating them is easier and they do not suffer from the candy wrapper effect. The top one uses linear blend skinning with matrices and the bottom one uses dual quaternion skinning.

Cons:

-They cannot represent shearing.
-GLSL does not support them out of the box. (You have to write the multiplication code yourself; it is almost as fast as a matrix multiplication.)

I also improved the vec3.translateQuat.
Here is a fixed benchmark: https://jsperf.com/quaternion-transform-vec3-implementations-fixed (The benchmark's code was wrong)

If you feel like this doesn't fit into the library, feel free to not accept the pull request.

Added a fromRotation and improved the multiplication by a quat

Getting the new functions...

Now it only uses 1 array to represent a dual quaternion

stefnotch · 2017-03-12T15:47:51Z

I finally finished optimizing all of the code.

Here is the code
Documentation: https://stefnotch.github.io/gl-matrix/

Should I remove some of the useless comments. (The previous implementations of a function...)

Ok, merged

kevzettler · 2017-10-15T18:47:30Z

Further discussion of this PR at: #221

I think this is a valuable addition to the library. Was about to start implementing these functions myself and was glad to find this PR and issue

kevzettler · 2017-10-15T18:57:53Z

@stefnotch I left some comments on some TODO FIX ME lines. It's unclear to me if there are outstanding issue with the PR.

Should I remove some of the useless comments. (The previous implementations of a function...)

It is a best practice to remove any dead comments, or code from a final PR.

kevzettler · 2017-10-15T18:53:42Z

src/gl-matrix/mat4.js

@@ -946,6 +946,38 @@ export function fromRotationTranslation(out, q, v) {
  return out;
 }

+//TODO FIX ME


Whats the Issue here?

kevzettler · 2017-10-15T18:54:11Z

src/gl-matrix/vec3.js

@@ -520,31 +520,43 @@ export function transformMat3(out, a, m) {
  return out;
 }

+//TODO Fix me (upgrade the function signature)


TODO whats the issue with the signature?

stefnotch · 2017-10-15T19:05:24Z

Great to see that somebody is interested! I'll go and fix those as soon as possible. (Should be done by next Sunday. Hopefully sooner.)

I'm not sure about those comments, they might be related to the fact that the library switched their module system at some point.

kevzettler · 2017-10-15T19:15:33Z

docs/quat2.js.html

+//https://github.com/mosra/magnum/blob/master/src/Magnum/Math/DualQuaternion.h#L364
+//http://mosra.cz/blog/magnum-doc/classMagnum_1_1Math_1_1DualQuaternion.html#a6dcad20c0e9c7c9361b9c291ee42b181
+/**
+ * @class Dual Quaternion&lt;br>Format: [[real],[dual]]&lt;br>Make sure to have normalized dual quaternions, otherwise the functions may not work as intended.


confused here isn't the format [real, dual] ? maybe this needs to be updated

Yeah, you are right

kevzettler · 2017-10-15T19:18:19Z

docs/quat2.html

+
+        <h2><span class="attribs"><span class="type-signature"></span></span>quat2<span class="signature">()</span><span class="type-signature"></span></h2>
+
+            <div class="class-description">Dual Quaternion<br>Format: [[real],[dual]]<br>Make sure to have normalized dual quaternions, otherwise the functions may not work as intended.</div>


Should the format be [real, dual] here?

stefnotch · 2017-10-25T15:54:11Z

Ok, here is what I still have to do:

slerp
rotateAroundAxis (unit tests only)

Should I implement those 2 functions?

lookAt
forEach

kevzettler · 2017-10-25T16:07:43Z

great work on this!

I need some clarification on what you are asking.

Should I implement those 2 functions?

lookAt
forEach

Are you saying you haven't implemented these two functions? or wrote tests for them? If that's the case I think lookAt would be important to implement. Reasons being; its consistent with the other data structure functionality in gl-matrix.

forEach I'm not as sure on. Is it an iterator method from the individual quats in a quat2 ?

Either way, I don't think either lookAt or forEach is a blocker to this PR. They can be added in on later PR's when there is community demand for it.

stefnotch · 2017-10-25T16:13:09Z

I have not implemented these 2 functions yet.

Ok, I guess I'll implement lookAt!
Edit: I have no clue how to implement lookAt.

forEach would be similar to vec3.forEach. I guess I won't implement it for now and add it at a later date if there is any demand for it.

Feel free to implement it.

(Hopefully)

stefnotch · 2017-10-27T10:16:09Z

@kevzettler @toji @sinisterchipmunk @chinedufn
I'm happy to report that I am done with the dual quaternion implementation!

kevzettler

@stefnotch thanks for all your work here this is looking great! I left a review with some inline comments where I had concerns. Please address at your convience.

kevzettler · 2017-10-31T15:40:34Z

docs/mat4.js.html

@@ -974,6 +974,38 @@ <h1 class="page-title">Source: mat4.js</h1>
  return out;
 }

+//TODO FIX ME


Is this outstanding?

That's a documentation file. I didn't rebuild the docs. (Should probably do it)

kevzettler · 2017-10-31T15:41:40Z

docs/vec3.js.html

@@ -548,31 +548,43 @@ <h1 class="page-title">Source: vec3.js</h1>
  return out;
 }

+//TODO Fix me (upgrade the function signature)


Is this new? why does the signature need to change?

Fixed. (Only had to rebuild the docs.)

kevzettler · 2017-10-31T15:43:17Z

spec/gl-matrix/quat2-spec.js

+    describe("translate", function() {
+        var matrixA = mat4.create(), matOut = mat4.create(), quatOut = quat2.create();
+        beforeEach(function() {
+              //quat2A only seems to work when created using this function?


Any idea whats up here?

No clue. I'm also confused.

It might be possible that quat2A isn't really a valid dual quaternion, however my maths isn't anywhere near good enough to figure out if that is, in fact, the case.

kevzettler · 2017-10-31T15:45:32Z

spec/helpers/spec-helper.js

@@ -3,6 +3,11 @@ const assert = require('assert');


 global.expect = function(e) {
+
+    function expected(e, message, a) {


I don't see this used anywhere below

It's a convenience function which is only used in the same file.
e.g. https://github.com/stefnotch/gl-matrix/blob/master/spec/helpers/spec-helper.js#L86

kevzettler · 2017-10-31T15:46:24Z

src/gl-matrix/mat4.js

+export function fromQuat2(out, a) {
+    //var normalizedA = quat2.create();
+    //quat2.normalize(normalizedA, a);
+    //quat2.getTranslation(translation, normalizedA);


remove unused commented code

Oh, my bad, I thought I had removed all of those comments.

kevzettler · 2017-10-31T15:54:05Z

src/gl-matrix/vec3.js

@@ -522,29 +522,40 @@ export function transformMat3(out, a, m) {

 /**
 * Transforms the vec3 with a quat
+ * Can also be used for dual quaternions. (Multiply it with the real part)
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the vector to transform
 * @param {quat} q quaternion to transform with
 * @returns {vec3} out
 */
 export function transformQuat(out, a, q) {


I don't think we should rewrite this function to handle parameter overriding for both quat and quat2 types. The gl-matrix library aims towards a 'functional programming' style of 'pure functions' which aims for static type style fixed function signatures. I would propose a new transformQuat2 method that explicitly handles the quat2 behavior.

:) I'm perfectly aware of it.

This thing works because a dual quaternion is represented by a flat array with 2 quaternions.
[x0, y0, z0, w0, x1, y1, z1, w1]
The first part is a perfectly normal, normalized quaternion which represents a rotation. The second part is a quaternion which represents a translation.

And, the function only looks at the first 4 elements of whatever array gets passed to it. In our case, it's the dual quaternion's rotation. It ignores the translation part, which is perfectly fine, because a vector doesn't really have a translation. (When you have a vector that represents a point, it's actually a vector from the origin to the point's coordinates.)

However, this comment might also cause some confusion. e.g.

Why doesn't this translate my vector?
transformQuat(out, [0,0,0], [no rotation, a translation])

(The answer would be: Because a vector only has a "magnitude (or length) and direction" --Wikipedia)

So, I guess it can be removed? If a person actually wants to rotate his vectors with a dual quaternion's rotation part, he probably knows his stuff and doesn't need this comment?

kevzettler · 2017-10-31T15:57:31Z

spec/gl-matrix/vec2-spec.js

@@ -330,7 +330,7 @@ describe("vec2", function() {

        beforeEach(function() { result = vec2.distance(vecA, vecB); });

-        it("should return the distance", function() { expect(result).toBeCloseTo(2.828427); });
+        it("should return the distance", function() { expect(result).toBeEqualish(2.828427); });


Why the change on assertions here?

I removed toBeCloseTo because it wasn't working properly and toBeEqualish does the exact same thing.

kevzettler · 2017-11-01T15:34:34Z

@stefnotch thanks for addressing comments. This lgtm, additional review from one of the maintainer's cc @toji @sinisterchipmunk is needed.

To re-emphasize the value prop here, I feel this is a relevant and powerful addition to the gl-matrix library. dual-quats are incredibly useful for skeletal animation. I personally am currently using dual-quat features with @chinedufn's https://github.com/chinedufn/skeletal-animation-system which is built on dual quats

stefnotch · 2017-12-13T15:26:08Z

So far, over a month has passed by and nothing has happened.

kevzettler · 2017-12-31T04:13:15Z

ping @toji @sinisterchipmunk

stefnotch · 2018-04-13T12:05:07Z

Note to self: Make sure that the quat2 code doesn't mess up the other code.

stefnotch · 2018-04-21T19:42:26Z

@chinedufn @kevzettler @Beeblerox

Dual quaternions are now a part of gl-matrix! 😃 Please report any bugs that you find. I'm also open to all suggestions.

stefnotch added 5 commits October 28, 2016 17:25

Dual Quaternion

dac4f72

Fixed some comments

d96f086

vec3 changes

1ee4658

Added a fromRotation and improved the multiplication by a quat

Reverted vec3.transformQuat

78b4d51

Improved vec3.transformQuat

661cd5a

stefnotch mentioned this pull request Nov 18, 2016

vec3.transformQuat uses slow implementation? #108

Closed

stefnotch and others added 9 commits November 19, 2016 21:02

fixed quat2.rotateAroundAxis bug

0e9951d

quat2.rotateByQuatAppend and quat2.rotateByQuatPrepend

68c970e

removed fromRotation

c1bdd86

Merge pull request #1 from toji/master

06ecd31

Getting the new functions...

Dual Quat lerp works properly now

bb8e670

Optimisations

720076e

Changed all of the code to [real dual]

2eeea77

Now it only uses 1 array to represent a dual quaternion

Docs are buggy?

014460f

Do the docs work?

58cd44e

stefnotch added 2 commits July 19, 2017 18:43

targetTo implementation

d04d19d

test

e634e3a

stefnotch mentioned this pull request Jul 20, 2017

lookAt is backward #225

Closed

stefnotch added 5 commits July 21, 2017 17:04

merging

f14a65f

merged

9646963

merged

0d7baaf

Merge branch 'toji-master'

d5de998

Ok, merged

Transition to something newer finished

e068c95

kevzettler reviewed Oct 15, 2017

View reviewed changes

Some test fixes

b840c9a

Cleaned up some unit tests

2ec3921

stefnotch added 5 commits October 25, 2017 19:06

Spec helper improvement

74eab39

Spec helper improvement

1500b76

Sclerp backup

871f6f8

ScLERP gone

d69506d

Feel free to implement it.

Final release

c767cc5

(Hopefully)

kevzettler suggested changes Oct 31, 2017

View reviewed changes

stefnotch added 3 commits October 31, 2017 17:56

Built the docs & stuff

8c74346

Removed some stray comments

362093a

Replaced var with let

2bbbdea

kevzettler mentioned this pull request Mar 19, 2018

github.com/gl-matrix/stefnotch kevzettler/gl-matrix#1

Open

stefnotch added 6 commits April 21, 2018 20:55

Making my stuff up to date again

256c001

Making my stuff up to date again

884c125

Pulled some stuff from toji/master

c358197

Merge conflicts

b80b4f3

Fixes

cbbf1b2

Minor fixes

e9fb60b

stefnotch merged commit 180b46f into toji:master Apr 21, 2018

kevzettler mentioned this pull request Apr 21, 2018

Migrate dual quat math to gl-matrix implementation chinedufn/skeletal-animation-system#10

Closed

snyk-bot mentioned this pull request Apr 24, 2020

[Snyk] Upgrade gl-matrix from 2.0.0 to 2.8.1 ukmadlz/battlehack-2013#4

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quat2 implementation #231

quat2 implementation #231

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		<h2><span class="attribs"><span class="type-signature"></span></span>quat2<span class="signature">()</span><span class="type-signature"></span></h2>

		<div class="class-description">Dual Quaternion<br>Format: [[real],[dual]]<br>Make sure to have normalized dual quaternions, otherwise the functions may not work as intended.</div>

		@@ -3,6 +3,11 @@ const assert = require('assert');


		global.expect = function(e) {

		function expected(e, message, a) {

quat2 implementation #231

quat2 implementation #231

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stefnotch commented Nov 10, 2016 • edited Loading

Pros:

Cons:

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