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Asked: 2025-02-06T06:14:14+05:30

How can I shrink a UI circle’s radius without deformation until it becomes a solid spot in screen space?

I’ve been stuck trying to figure out how to shrink a UI circle’s radius without distorting it. I stumbled upon this issue while working on a project where I need a ring that contracts down to a solid dot, but I’m not sure how to achieve the effect I want.

So, here’s the situation: I have this hollow circular UI element that I created, and I want to animate it shrinking smoothly without it looking like it’s just scaling down. You know how when you scale down a UI element, it can look kind of squished or warped? That’s exactly what I want to avoid. The goal is to keep the outline of the ring perfectly round and only shrink the space inside until it’s just a filled-in spot—totally solid.

I played around with using a line renderer for the circle, but since I’m working within a canvas that uses screen space instead of world space, I’m worried it won’t translate properly. Plus, I think there might be limitations with the line renderer that wouldn’t allow me to achieve the smooth, clean animation I’m aiming for.

I’ve tried a few things—such as manipulating the diameter or using masks to hide the hollow fill—but nothing feels right. I want it to look visually appealing and fluid, like it’s constricting evenly from every side until it disappears into a single pixel. I know there must be a way to do this that avoids the scaling issues, but I just can’t figure it out. Maybe it’s a matter of using a shader or something involving graphics programming that I’m not familiar with?

If anyone has dealt with a similar issue or has some tips on how to make this happen, I’d really appreciate it. Any suggestions on methods or even potential code snippets would be super helpful. I feel like I’m missing something obvious, and I’d love to hear how others have tackled similar challenges!

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    2 Answers

    1. It sounds like you’re on the right track, and I get how frustrating it can be when things don’t animate the way you want. To create that shrinking ring effect without distortion, you might want to consider using a combination of CSS animations and the border-radius property.

      Here’s a simple example of how you could achieve this effect using CSS:

      This code snippet creates a circular div that shrinks down to nothing smoothly. The border-radius: 50% keeps your circle from distorting as it animates. Just tweak the dimensions and animation speed as needed!

      If you want to keep it as a filled circle, just change the background color of the circle instead of using a border. Then animate only the width and height:

      Give that a try! You may want to play around with different properties or add easing for a more dynamic look. Keep experimenting, and don’t hesitate to reach out if you have more questions!

    2. To achieve a smooth shrinking effect for a hollow circular UI element without distortion, consider using an approach based on scaling the inner fill separately from the outline or employing a mask that transitions. Instead of simply scaling the whole circle, you can animate the position and size of a child element that represents the fill while keeping the outline constant. By adjusting the parameters of these elements over time, you can create a visually pleasing transition from a ring to a solid dot. Utilizing CSS transitions or animations, you can gradually decrease the size of the inner fill, allowing for a perfect circular shape maintained by the outline throughout the animation.

      If you’re comfortable with shaders or graphics programming, another appealing option could be to use a shader-based approach. This would typically involve manipulating fragment shaders where the ring’s radius is gradually reduced while maintaining its circular shape. If you prefer not to dive into shaders, you can use libraries like three.js or processing.js, which can handle animations fluently and provide built-in functionalities to create this effect. In both cases, the goal is essentially to animate two different elements: the fill and the outer outline, ensuring that the outer ring’s radius remains constant while the inner space contracts uniformly. This method allows for a clean and smooth visual effect as it transitions into a single pixel.