I’m currently writing a piece of code that would return the minimum distance you need to fully encapsulate a model at any camera orientation.
At first this seemed simple enough: Find the minimum radius that would fully encapsulate the subject model and then use some basic trig to calculate the distance from the camera.
sin(fov2) = radius / distance
distance = radius / sin(fov2)
This works great when the height of the viewport frame is larger or equal to its width, but when it’s not the sides of the object will get cut off.
width == height vs. width < height
As such we need to calculate a corrected distance
a = PI / 2 - FOV / 2
h2 = sin(a) * radius
d = cos(a) * radius
hw = viewportFrameSize.Y / viewportFrameSize.X
correctedDistance = (h2 * hw) / tan(fov2) + d
width == height vs. width < height
This is the full code:
function module.GetModelFitDistance(model, vpf, camera)
local modelCFrame, modelSize = model:GetBoundingBox()
local vpfSize = vpf.AbsoluteSize
local hw = math.max(1, vpfSize.Y / vpfSize.X)
local fov2 = math.rad(camera.FieldOfView / 2)
local alpha = math.pi/2 - fov2
-- just assume displacement == 0 for now
local displacement = (camera.Focus.Position - modelCFrame.Position).Magnitude
local radius = ((modelSize.Magnitude / 2) + displacement)
local h2 = math.sin(alpha) * radius
local d = math.cos(alpha) * radius
return (h2 * hw) / math.tan(fov2) + d
end
Right, so now with all that preamble out of the way onto my actual question!
I’m running into a weird issue where certain camera orientations leave ample room from the edges when the frame is square. However, these same orientations get cut off when width < height.
To me it seems to make no sense, we calculated a static distance that is guarnteed to fit the worst case scenario (and it seems to successfully do that), yet it fails when it should be nowhere near the maximum constraint?
Notice the left most side is starting to get cut off
So that makes me think this is caused by 1 of 2 things:
- I’ve done my math wrong (which I find hard to believe b/c as per earlier examples it fits perfectly)
- There’s some weird scaling factor going on w/ viewport frames that I’m not accounting for.
Any help would be greatly appreciated. I’ve attached the place file I used for the images here:
Fit viewport frame 2.rbxl (26.8 KB)
For refrence I was toggling the width of the viewport frame between 200 and 100 and the orientation around the y-axis between 90 and 45 degrees.
