Making an unmovable button

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Hello, so I'm new to programming / Unity and am currently making a 2d dungeon crawler. I am trying to make a button to "Speak to Old Man" and have it not move with my game (I.E make the button always appear directly under the Old Man), but have been having difficulties. I originally tried having the button and dialogue box share a canvas, but couldn't figure out how to make the button stay directly underneath the old man. I then tried creating a second canvas with render mode World Space and placing the button in there but it then becomes invisible no matter the sorting layer I set it to.

Current example with 1 canvas: link: [1]: https://gyazo.com/694011d0b2076730d492ebaf9d6fe96d

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Answer by Fressbrett · Jun 29 at 06:23 PM

You actually do want to use a worldspace canvas for that, they are built exactly for the kind of situations you are dealing with, a moving camera while the canvas should stay on a fixed worldposition. Using an overlay canvas or a screen space canvas will keep the canvas on the same position on the screen, but with a moving camera that is not what you want here.

Your problem seems to be that your canvas is invisible when set to worldspace. There are multiple ways to fix this:

First of all, imagine your worldspace canvas like an actual object within your scene, which thus can also be obstructed by anything infront of it. So check that the z position of your canvas is closer to the camera than the z position of all other objects on your screen.
Depending on your Render Pipeline you can also create "global sorting rules" for rendering. Within the URP (Universal Render Pipeline) for instance you can create "Render Features" within your ForwardRenderer asset, in which you could define that all objects on the layer "UI" should always render AFTER all other opaque objects have rendered (or after post processing... whatever you want). Using this approach it doesn't matter anymore what Z position your canvas has, it will be always rendered infront of all other stuff.

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JstizUnity · Jun 29 at 08:13 PM 0

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Thank you for the response, do you think I should I accomplish this by making a second canvas with only the button on it? Or editing my existing canvas (that contains my dialogue box, etc.) and making that into worldspace?

Fressbrett JstizUnity · Jun 30 at 10:46 AM 1

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Everything that should move with the camera, for instance a health bar, can be kept in a single (overlay or screenspace) canvas, since the position of those will be "fixed" relative to the camera.

Everything you want to display within the world needs to be in a worldspace canvas. You don't want EVERYTHING within your world on a single worldspace canvas. Instead, try to group things cleverly:

You talked about the button underneath the old man, which is an object within your world. Say that old man moves, then everything UI related that should move with that old man can be in a single worldspace canvas that is child of that old man object.

Similarly, the "+5 Coins" that appear when you open that chest could be displayed on its own canvas child of that Chest.

It's good practice to separate things into multiple canvases, since when one element changes (for instance when your coin message appears once you open the chest), then the whole canvas needs to be redrawn, even other text that might not have changed (the old man button in this case). That is pretty resource intensive, thus you want to separate those into different canvases. Read this guide for more on best practices when it comes to canvases.

JstizUnity Fressbrett · Jun 30 at 10:09 PM 0

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Thanks a lot man, makes so much more sense now! One final question I do have. When reading other guides and such I've mentioned others say this similar thing of making an object a child of another object. What exactly does this mean? Or if you know of a nice video explaining it that would be very cool. Thanks again.

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Answer 2

Answer by vish_faldu · Jun 29 at 09:54 AM

You can look into the concept of Overlay Camera.

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Fressbrett · Jun 29 at 06:15 PM 0

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I believe he wants to achieve the opposite, he wants the button stay "under the old man" which is a worldspace postion. Thus world space canvas should be the way to go.

Making an unmovable button

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