Add CollectPointsWithUV for colored point clouds

[berkut0]

Problem

To create colored point clouds, it's necessary to sample the color camera image. However, since the color camera image doesn't align "one-to-one" with the depth sensor image, the Kinect SDK provides a special tool to get UV coordinates for each point. Previously, this tool was not exposed, making it impossible to get UV coordinates for point clouds. This was an oversight.

Solution

This PR adds CollectPointsWithUV method that generates UV coordinates alongside point positions, allowing users to color point clouds by sampling the color texture in shaders.

Changes

• Added CollectPointsWithUV method in PointCloud.cs that returns SpreadBuilder<(Vector3 position, Vector2 uv)>
• Added PointCloudWithUV node for use in VVVV Gamma
• Added PointCloudWithUV (Reactive) node for reactive API

Technical Details

• UV coordinates are normalized to 0..1 range (compatible with shaders)
• Uses MapDepthFrameToColorSpaceUsingIntPtr from Kinect SDK
• Dynamically gets color frame dimensions from KinectSensor.ColorFrameSource.FrameDescription
• Invalid UV coordinates cause the entire point to be dropped (maintains synchronization)
• Compatible with Observable pattern via HoldLatestCopy

[berkut0]

[joreg]

thanks for this already!
in order to help us review this: would you mind adding screenshots that show your case in the vl document? i'm also wondering if a change in a helppatch should be necessary? or a new helppatch?

[berkut0]

@joreg I have only used VL.FUSE and, to be honest, I have little idea how to use it in ‘vanilla’ Stride. Therefore, I think that if we make a help patch, it should be purely as a demonstration of the idea without any specific implementation (so as not to tie the patch to VL.FUSE). However, it's up to you.

kinect.zip

[joreg]

ok, but also i meant screenshots of the changes you did in the .vl doc

[berkut0]