Asking where the drawn world is along a ray

Asking where the drawn world is along a ray

renderer.raycast(origin, direction, maxDistance?, exclude?) reports the nearest surface the renderer DRAWS along a ray, and renderer.raycastAll every surface along it, nearest first. Both answer for a mesh whether or not anything gave it a rigid body, so a terrain, a procedurally generated mesh, or any plain Model reports the surface under a point.

The answer is the nearest triangle of the mesh, so a sloped or terraced surface reports its height where it was asked rather than the extent of its bounding box:

local hit = renderer.raycast({ x, 100, z }, { 0, -1, 0 }, 200)
if hit then
    print(hit.entityId, hit.point.y, hit.normal.y, hit.distance)
end

A hit carries entityId, the world-space point, a unit normal turned to face back along the ray, the distance from the origin, the meshGuid, and exact — true where the answer came from a triangle, false where a mesh's vertices live on the GPU alone and the object's bounds are the whole answer. distance is measured in world units — the direction is normalised, at any length you hand it in — so it is directly comparable to a physics.raycast distance along the same ray. The triangles walked are the mesh's own, placed by the entity's transform and by the mesh's bind pose, so a surface a skinning or morph pass deforms on the GPU answers as the geometry the mesh holds.

Everything drawn is in scope — the ground you meant, and equally a character standing on it, a prop, or a placeholder floor left in the scene. Read entityId before trusting a height, step over what you did not mean with exclude, or take the whole column with raycastAll and pick the surface yourself:

-- the ground under a camera station, ignoring whoever is standing there
local hit = renderer.raycast({ x, 100, z }, { 0, -1, 0 }, 200, { playerId })

-- or: every surface in the column, choose the one you are after
for _, h in renderer.raycastAll({ x, 100, z }, { 0, -1, 0 }, 200) do
    if h.entityId == groundId then print(h.point.y) end
end

physics.raycast answers from colliders instead, which is the query for what a body would collide with; this one is the query for what a camera would see.