Fixed width, relative height, on different aspect ratio screen?

Question

I am developing a game in portrait view. I encounter a problem when the game running on different aspect ratio. On taller screen the camera clip the horizontal view. I am expecting a fixed horizontal view, and the clip should be on the vertical view. How can I achieve this on perspective camera and ortographic camera?

I think I can calculate the ortographic size to fit the width, and there is some answer about it. But I think the perspective size cannot easily calculated because of frustum and field of view.

alt text

Answer 1

Answer by Cthaeh23 · Mar 28, 2017 at 03:14 PM

Here my solution for perspective cameras:

 //Set a fixed horizontal FOV
 private float horizontalFOV = 120f;

 //somewhere in update if screen is resizable
 cam.fieldOfView = calcVertivalFOV(horizontalFOV, Camera.main.aspect);
 
 private float calcVertivalFOV(float hFOVInDeg, float aspectRatio)
     {
         float hFOVInRads = hFOVInDeg * Mathf.Deg2Rad;  
         float vFOVInRads = 2 * Mathf.Atan(Mathf.Tan(hFOVInRads / 2) / aspectRatio);
         float vFOV = vFOVInRads * Mathf.Rad2Deg;
         return vFOV;
     }

Some explanation:

In Unity you can only influence the aspect and the vertical FOV.

From a given vertical FOV and the aspect ratio Unity calculates the horizontal FOV. So depending on the aspect ratio the horizontal FOV will change.

Now to get a fixed horizontal FOV I calculate the vertical FOV to the current aspect ratio and apply it to the camera. This way the horizontal FOV is fixed and the vertical will change.

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Cthaeh23 · Mar 28, 2017 at 03:00 PM 1

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Credits to: https://gist.github.com/coastwise/5951291 $$anonymous$$y answer is just the inverse function.

atreyu64 · Oct 03, 2017 at 10:51 PM -1

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Thank you so much, it works great, exactly what I was looking for !

DevDop · Apr 18, 2018 at 04:50 PM 0

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Thank you so much, it works perfectly!

DevDop · Apr 18, 2018 at 04:51 PM 0

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Just in case someone sees this, with the last version of Unity you need to replace "cam." with "GetComponent()." ;)

davitsedrakian · Nov 14, 2019 at 05:03 PM 0

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that was great solution, and thank you for snippet and detailed explaination

Answer 2

Answer by HungryGames · Dec 12, 2014 at 03:52 AM

camera.orthographicSize = camera.orthographicSize * defaultAspect / camera.aspect;

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PouleyKetchoup · Feb 10, 2017 at 01:26 PM 1

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It worked great for me in the case of an orthographic camera!

I've implemented it this way in order to switch between respecting width or height depending on the aspect ratio:

 // initialSize is the default Camera.main.orthographicSize
 // targetAspect is the desired aspect ratio
 if (Camera.main.aspect < 1.6f)
 {
     // respect width (modify default behavior)
     Camera.main.orthographicSize = initialSize * (targetAspect / Camera.main.aspect);
 }
 else
 {
     // respect height (change back to default behavior)
     Camera.main.orthographicSize = initialSize;
 }

LilGames PouleyKetchoup · Jan 03 at 09:31 PM 0

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I'm loving this answer, but having trouble adapting it so the Horizontal FOV changes to always keep the WIDTH.

yong2khoo · May 02, 2021 at 10:26 AM 0

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thanks for your answer. i finally see some light in 2021. Portrait game supposed will encounter issue for multiple resolution. without compromising with the use of UI elements, guess changing orthographicSize as you mentioned, is the only way.

Answer 3

There's 2 way you can solve this problem:

By Changing the Camera FOV

It is the easiest solution, what you need to do is to set the Horizontal Camera FOV to The expected FOV or what i prefer "The design FOV"

Ex :

 var designAspect = 2/3; // We'll be using 3 by 2 aspect ratio in Portrait mode
 // "Aspect" is width divided by height
 
 var cameraVerticalFOV = camera.fieldOfView; // The camera FOV is the verticall one
 var cameraHorizontalFOV = camera.aspect * cameraVerticalFOV;
 
 var horizontalDesignFOV = designAspect * cameraVerticalFOV;
 // The verticall FOV is the same because the camera fixed height

 var multiplier =  (horizontalDesignFOV / cameraHorizontalFOV);
 // Multiplies the the vertical camera FOV into the vertical design FOV
 
 camera.fieldOfView *= multiplier; 
 // Apply the multiplier

By Zooming the camera by moving it foward or backwards

Here's an example problem to give you a Concept

The Camera doesn't see the full Object like you designed before because of the Camera Dynamic Width alt text You need to calculate The Distance to Move the Camera so it can see the full object

Let's call the line with dashes on it the Meetup Line

P is the position of the T on the Z-Axis

T is half of the MeetUp Line

and D is the distance between a Camera and the MeetUp Line

alt text

You just need to find the Difference of D in Camera A and Design Camera

Here's how you can find it :

First, calculate the T

using the D in the Designed Camera, let's say it's "10 Meters"

 var designHorizontalFOV = designAspect * camera.fieldOfView;
 
 var designTheta = designHorizontalFOV / 2;
 
 var T = Mathf.Tan(Mathf.Deg2Rad * (designTheta)) * 10;
 // "Deg2Rad" convert Degrees to Radians

Then,

You'll need to calculate D for Camera A

 var horizontalCameraAFOV = camera.aspect * camera.fieldOfView;

 var horizontalCameraATheta = horizontalCameraAFOV / 2;

 var cameraA_D = T / Mathf.Tan(Mathf.Deg2Rad * horizontalCameraATheta); // Get the "D"

After That,

you just need to Subtract and Move the Camera

 var camera_A_Displacement = cameraA_D - designCamera_D;
 // The difference betwen Two "D"
 
 camera_A.transform.localPosition = new Vector3(0,0,-camera_A_Displacement);
 // Minus sign to Move the Camera Backwards

If you prefer this method you can also Give a parent to the Camera, so you can move the camera or rotate it without Affecting its zoom by moving or rotating the Parent instead of the Camera directly

I Personally prefer the Second One because i don't need to Mess up with the FOV

The screen orientation on this Answer is Portrait

If there's a mistake that i made or any explanation that you don't understand, Please tell me.

Answer 4

Answer by DominoOne · Apr 06, 2016 at 02:57 PM

I know it's an old thread, but people might still end up looking for an answer.

For orthographic cameras it's much easier and has been answered already. For perspective ones, however, you need some trigonometry. All the necessary info about that is here: https://en.wikipedia.org/wiki/Angle_of_view

If you want an easy way out, though, here's a solution that works with all camera types: https://assetstore.unity.com/packages/tools/camera/camera-fit-screen-handler-57439?aid=1101l3r5C

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Fixed width, relative height, on different aspect ratio screen?

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