[API Proposal]: Billboard Lefthanded APIs for System.Numerics.Matrix4x4

[sqeezy]

Background and motivation

Matrix4x4 recently added APIs for left handed creation of Matrix4x4. Replacing another matrix implementation led me to nice the billboard APIs did not get left handed equivalents. In order to not confuse people about which functions are actually expecting a right handed system, we should add left handed versions for the billboard APIs.

API Proposal

namespace System.Numerics;

public partial struct Matrix4x4
{
 public static Matrix4x4 CreateBillboardLeftHanded(Vector3 objectPosition, Vector3 cameraPosition, Vector3 cameraUpVector, Vector3 cameraForwardVector)
 public static Matrix4x4 CreateConstrainedBillboardLeftHanded(Vector3 objectPosition, Vector3 cameraPosition, Vector3 rotateAxis, Vector3 cameraForwardVector, Vector3 objectForwardVector)
}

API Usage

var billboardLeftHanded = Matrix4x4.CreateBillboardLeftHanded(objectPosition, cameraPosition, cameraUpVector, cameraForwardVector);
...
var billboardConstrainedLeftHanded = Matrix4x4.CreateConstrainedBillboardLeftHanded(objectPosition, cameraPosition, rotateAxis, cameraForwardVector, objectForwardVector);

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Issue Details

---

Background and motivation

Matrix4x4 recently added APIs for left handed creation of Matrix4x4. Replacing another matrix implementation led me to nice the billboard APIs did not get left handed equivalents. In order to not confuse people about which functions are actually expecting a right handed system, we should add left handed versions for the billboard APIs.

API Proposal

namespace System.Numerics;

public partial struct Matrix4x4
{
public static Matrix4x4 CreateBillboardLeftHanded(Vector3 objectPosition, Vector3 cameraPosition, Vector3 cameraUpVector, Vector3 cameraForwardVector)
public static Matrix4x4 CreateConstrainedBillboardLeftHanded(Vector3 objectPosition, Vector3 cameraPosition, Vector3 rotateAxis, Vector3 cameraForwardVector, Vector3 objectForwardVector)
}


### API Usage

```csharp

var billboardLeftHanded = CreateBillboardLeftHanded(objectPosition, cameraPosition, cameraUpVector, cameraForwardVector);
...
var billboardConstrainedLeftHanded = CreateConstrainedBillboardLeftHanded(objectPosition, cameraPosition, rotateAxis, cameraForwardVector, objectForwardVector);
}


### Alternative Designs

_No response_

### Risks

_No response_

<table>
 <tr>
 <th align="left">Author:</th>
 <td>sqeezy</td>
 </tr>
 <tr>
 <th align="left">Assignees:</th>
 <td>-</td>
 </tr>
 <tr>
 <th align="left">Labels:</th>
 <td>

`api-suggestion`, `area-System.Numerics`, `untriaged`

</td>
 </tr>
 <tr>
 <th align="left">Milestone:</th>
 <td>-</td>
 </tr>
</table>
</details>

[terrajobst]

Video

• Looks good as proposed

namespace System.Numerics;

public partial struct Matrix4x4
{
 public static Matrix4x4 CreateBillboardLeftHanded(Vector3 objectPosition, Vector3 cameraPosition, Vector3 cameraUpVector, Vector3 cameraForwardVector);
 public static Matrix4x4 CreateConstrainedBillboardLeftHanded(Vector3 objectPosition, Vector3 cameraPosition, Vector3 rotateAxis, Vector3 cameraForwardVector, Vector3 objectForwardVector);
}