[WIP] [2.0] A maths library for Silk.NET #190

Perksey · 2020-06-15T15:41:26Z

HELP WANTED!

Help us implement the maths library (intrinsics not required, can be done at a later date)

Nice-to-haves

Brush up & expose Scalar
Plane - a plane in 3D space.
Curve3 - a quadratic bezier curve
Curve4 - a cubic bezier curve

Information about generic implementations

    /* Note: The following patterns are used throughout the code here and are described here
    *
    * PATTERN:
    *    if (typeof(T) == typeof(int)) { ... }
    *    else if (typeof(T) == typeof(float)) { ... }
    * EXPLANATION:
    *    At runtime, each instantiation of Vector<T> will be type-specific, and each of these typeof blocks will be eliminated,
    *    as typeof(T) is a (JIT) compile-time constant for each instantiation. This design was chosen to eliminate any overhead from
    *    delegates and other patterns.
    */

public static Vector2<T> Add(Vector2<T> left, Vector2<T> right)
{
    if (typeof(T) == typeof(float))
    {
        var leftF = (Vector2<float>)(object)left;
        var rightF = (Vector2<float>)(object)right;
        return (Vector2<T>)(object)new Vector2<float>(leftF.X + rightF.X, leftF.Y + rightF.Y);
    }
    else if (typeof(T) == typeof(double))
    {
        // etc
    }
}

Summary of the PR

Adds a maths library that patches in the holes left by System.Numerics.

What version does this PR target?

2.0

Related issues, Discord discussions, or proposals

Links go here.

Further Comments

john-h-k · 2020-06-15T15:55:55Z

aren't some of these types a bit redundant given SysNumerics (~~and mathsharp~~)

HurricanKai · 2020-06-15T15:56:02Z

should implementations forward to .net (5) implementations as much as possible or re-implement everything?

HurricanKai · 2020-06-15T15:59:29Z

also, will this be available to other projects separately?
If so, I'd be happy to implement Vector2/3/4 Half/Int/Long/float/double
should be mostly copy-paste

Perksey · 2020-06-15T16:00:01Z

@HurricanKai We can forward the float implementations to System.Numerics using Unsafe where applicable they'll likely be faster. Given that this is primarily targeting .NET Standard 2.0 (apart from hardware acceleration which will be done via multi-targeting), there's not much else we can do forwarding-wise.

@HurricanKai (2) Yep, it won't even depend on Silk.NET.Core. It will be entirely standalone.

@john-h-k There's no way I'll get the APIs I want in System.Numerics within this decade due to API review, so I have to do it here. As for MathSharp, well I mean MathSharp's just an intrinsics library right (albeit providing some minimal storage types)

HurricanKai · 2020-06-15T16:17:09Z

@Perksey In line with what dotnet/runtime does, and also because I'd think performance wise it makes more sense, I'd suggest things like One/Zero/UnitX etc. be (static) properties

Perksey · 2020-06-15T16:17:45Z

Yeah that'd make more sense, fine by me 👍

HurricanKai · 2020-06-15T16:34:14Z

What is private static readonly string ListSeparator; for?
Seems like that should just be NumberFormatInfo.GetInstance(formatProvider).NumberGroupSeparator;

Perksey · 2020-06-15T16:35:18Z

Yeah that's what it should be, didn't take into account NumberFormatInfo when originally speccing the API

HurricanKai · 2020-06-15T16:36:57Z

What's LengthFast?
There seem to be a lot of Fast methods? why would anyone not choose those?

Perksey · 2020-06-15T16:42:13Z

Ah you can ignore that, Length was gonna be Math.Sqrt((X * X) + (Y * Y)) whereas LengthFast was gonna be 1.0 / InverseSqrtFast((X * X) + (Y * Y) + (Z * Z) + (W * W)) where InverseSqrtFast is:

var xhalf = 0.5f * x;
var i = *(int*)&x; // Read bits as integer.
i = 0x5f375a86 - (i >> 1); // Make an initial guess for Newton-Raphson approximation
x = *(float*)&i; // Convert bits back to float
x = x * (1.5f - (xhalf * x * x)); // Perform left single Newton-Raphson step.
return x;

But in this day and age LengthFast is probably slower so you should just remove LengthFast, as well as most other *Fast methods as the implementation you come up with is likely as fast as it can be, and adding "fast" overloads will probably just end up confusing users.

Sorry about all this, I had pulled up on the other screen the API spec for another maths library and wrote the overloads without thinking.

john-h-k · 2020-06-15T17:32:35Z

where InverseSqrtFast is:

or just use Sse.ReciprocalSqrt 😄 which is an approximation and super super fast (way faster than 1 / qsrt)

Perksey · 2020-06-15T17:37:05Z

Hardware acceleration is coming after we have initial software prototypes ;)

…

On Mon, 15 Jun 2020 at 18:32, John Kelly ***@***.***> wrote: where InverseSqrtFast is: or just use Sse.ReciprocalSqrt 😄 which is an approximation and super super fast (way faster than 1 / qsrt) — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#190 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACVEYI4MNCXK57WBE7NB6DLRWZLMDANCNFSM4N6JRMDQ> .

HurricanKai · 2020-06-15T18:01:46Z

what is PerpDot for? very ambiguous, and if I understand what it means, is easily doable using PerpendicularLeft + Dot

Perksey · 2020-06-15T18:09:54Z

The perpendicular dot product is (left.X * right.Y) - (left.Y * right.X);

HurricanKai · 2020-06-15T18:11:51Z

What is BaryCentric supposed to do, if I understand wikipedia correctly, I can't implement it without assuming in what kind of coordinate system X & Y are. For all I know X & Y could already be Barycentric coordinates...

Perksey · 2020-06-15T18:14:15Z

Ah it interpolates 3 Vectors using Barycentric coordinates (so it returns a when u=0v=0, b when u=1,v=0, c when u=0,v=1, and a linear combination of a,b,c otherwise).

We should probably move these questions to Discord and the GitHub thread is getting pretty full

* Add Scalar<T>.Two * Add Scalar<T>.Smaller * Add Scalar<T> SmallerEquals & LargerEquals * Implement Box2<T> * Make Min/Max public * Missed Equals * Box3<T> * Make Box2/3 readonly * Add With methods * Rename past tense Methods

* Make Vecttor2<T> readonly * Make Vector3<T> readonly * Make Vector4<T> readonly * Rename past tense Methods

HurricanKai · 2020-06-18T04:26:18Z

Will begin with Matrix4x4 :)

Perksey · 2020-06-18T12:40:33Z

Awesome :D

* Nullability * CLS compliance * Rename CLSCompliant.cs to AssemblyInfo.cs * <Nullable>enable</Nullable>

HurricanKai · 2020-06-18T18:50:23Z

All Scalar methods with 9+ block need to be split up into multiple < 9 block functions.
See dotnet/runtime#38106

Perksey · 2020-06-18T18:52:53Z

Damn that is really really unfortunate, but necessary if it poses a nuisance. I'm fine with that being done, albeit a little sad.

HurricanKai · 2020-06-18T20:56:20Z

For reference, One, Tau etc. don't seem to be affected.
Methods like Multiply seem to be affected:
Normal Multiply:

G_M60209_IG01:
       4883EC28             sub      rsp, 40
       C5F877               vzeroupper 

G_M60209_IG02:
       C5FA100519000000     vmovss   xmm0, dword ptr [reloc @RWD00]
       C5FA100D15000000     vmovss   xmm1, dword ptr [reloc @RWD04]
       E894F7FFFF           call     Silk.NET.Maths.Scalar`1[Single][System.Single]:Multiply(float,float):float
       90                   nop      
G_M60209_IG03:
       4883C428             add      rsp, 40
       C3                   ret      
RWD00  dd    3FC90FDBh
RWD04  dd    40000000h

Split Multiply:

G_M60209_IG01:
       C5F877               vzeroupper 
G_M60209_IG02:
       C5FA100505000000     vmovss   xmm0, dword ptr [reloc @RWD00]
G_M60209_IG03:
       C3                   ret      
RWD00  dd    40490FDBh

that's a rather big difference for a multiply

Perksey · 2020-06-18T21:37:22Z

Interesting, that is a massive improvement.

HurricanKai · 2020-06-19T11:26:55Z

currently exposing more of Math/MathF and doing all the optimizations in Scalar<T> but it seems we at least end up with a call for Math/MathF :/

* Add Basic Scalar Tests & Fix Scalar mistakes * netcoreapp5.0 -> net5.0

john-h-k · 2020-06-20T16:06:08Z

src/Maths/Silk.NET.Maths/Scalar.cs

@@ -248,57 +248,57 @@ public static T SquareRoot(T value)
        {
            if (typeof(T) == typeof(byte))
            {
-                return (T) (object) (MathF.Sqrt((byte) (object) value));
+                return (T) (object) (byte) (MathF.Sqrt((byte) (object) value));


Don't lie about integral square root. Either this should use an integral square root path, or it should be not supported. Users will get very unexpected results doing this

john-h-k · 2020-06-20T16:06:31Z

src/Maths/Silk.NET.Maths/Scalar.cs

@@ -1071,12 +1071,12 @@ public static T Acos(T value)

            if (typeof(T) == typeof(ulong))
            {
-                return (T) (object) (Math.Acos((ulong) (object) value));
+                return (T) (object) (ulong) (Math.Acos((ulong) (object) value));


CC above. You shouldn't "fake" floating point ops on integral types

* Remove .net standard testing targets * Add Shared Floating Point Scalar Tests * Scalar Improvements + Cleanup

Co-authored-by: Dylan Perks <dmp9biz@gmail.com>

Perksey · 2020-07-20T14:10:45Z

@HurricanKai It's probably best we close this PR and reopen it anew seeing as you've taken over maths development - the PR is currently still in my name.

HurricanKai · 2020-07-20T14:11:56Z

👍

Perksey added 3 commits June 13, 2020 00:17

Lay out initial API

4bacdf0

take a different approach

ee519fd

Lay out initial API

750fa65

pull-request-size bot added the size/XXL label Jun 15, 2020

Perksey added help wanted Extra attention is needed and removed size/XXL labels Jun 15, 2020

Perksey added this to the 2.0 milestone Jun 15, 2020

Perksey added the size/XXL label Jun 15, 2020

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HurricanKai added 2 commits June 17, 2020 22:14

Box2<T> Box3<T> (#194)

a50ef33

* Add Scalar<T>.Two * Add Scalar<T>.Smaller * Add Scalar<T> SmallerEquals & LargerEquals * Implement Box2<T> * Make Min/Max public * Missed Equals * Box3<T> * Make Box2/3 readonly * Add With methods * Rename past tense Methods

Readonly Vectors (#195)

df1d767

* Make Vecttor2<T> readonly * Make Vector3<T> readonly * Make Vector4<T> readonly * Rename past tense Methods

Nullability (#196)

9024067

* Nullability * CLS compliance * Rename CLSCompliant.cs to AssemblyInfo.cs * <Nullable>enable</Nullable>

Add Basic Scalar Tests & Fix Scalar mistakes (#198)

a80df9a

* Add Basic Scalar Tests & Fix Scalar mistakes * netcoreapp5.0 -> net5.0

john-h-k suggested changes Jun 20, 2020

View reviewed changes

HurricanKai and others added 7 commits June 20, 2020 22:00

Scalar2 (#200)

d6c9f94

* Remove .net standard testing targets * Add Shared Floating Point Scalar Tests * Scalar Improvements + Cleanup

Swizzle Operators (#201)

ca77a51

Downsizing Swizzle operators (#202)

5b1c4f0

Quaternion<T> (#205)

4d8ff21

Better hash codes (#206)

0277cd8

merge

2f4ab72

Merge branch '2.0' into feature/maths

ad650ac

This was referenced Jun 30, 2020

[2.0] Source Link #213

Closed

Finalize Maths API #215

Closed

Perksey mentioned this pull request Jul 5, 2020

[2.0] DegreesToRadians and other scalar maths helpers. #219

Closed

Perksey removed the help wanted Extra attention is needed label Jul 19, 2020

Merge branch '2.0' into feature/maths

165d45b

Perksey requested a review from HurricanKai as a code owner July 20, 2020 14:00

[WIP] Maths Tests & Final API (#242)

e4faecb

Co-authored-by: Dylan Perks <dmp9biz@gmail.com>

HurricanKai closed this Jul 20, 2020

HurricanKai mentioned this pull request Jul 20, 2020

[WIP] [2.0] A maths library for Silk.NET #252

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[WIP] [2.0] A maths library for Silk.NET #190

[WIP] [2.0] A maths library for Silk.NET #190

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[WIP] [2.0] A maths library for Silk.NET #190

[WIP] [2.0] A maths library for Silk.NET #190

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HELP WANTED!

Nice-to-haves

Information about generic implementations

Summary of the PR

What version does this PR target?

Related issues, Discord discussions, or proposals

Further Comments

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