frustum

You can accept that, use many rays, or do proper view frustum/body model(simplified probably) intersection, after cutting the view frustum with the terrain.

And projection space has 0.0 at the near plane of the view frustum and 1.0 at the far end.

The linked video shows a third person view of the user's frustum/field of view in Hololens.

Each ray is a sample and these are cast from the focal point, through the view frustum, and the colour is calculated where it intersects an object in the scene.

Meaning that every dead and then-living human was within the camera's view frustum, except for the three in the spacecraft.

You use perspective and perspective-origin to create the view frustum, and then CSS transforms to place your elements in 3D space.

Come, every frustum longs to be a cone, And every vector dreams of matrices.

The game still needs to make sure it doesn't give the hardware too much stuff that isn't actually intersecting with the view frustum.

You can see the same scaling by changing the frustum viewing angle (i.e.

Are they all just assigned to an octtree and then culled against the view frustum or do you really need some clever occlusion culling?

The hardware expects a list of pretty basic primitives, and takes care of transforming them into the view frustum, with depth converting into Z-buffer value.

In fact to even achieve some basic correctness will require quite a degree of complexity: the primitive assembler will of course need frustum- and back-face culling (and these will mean re-triangulating some primitives).

Note, the "Frustum" example[0] linked on the 3D perspective page[1] is not working on Firefox (screenshot comparing FF and Chrome[2]).