CsPaint questions

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rconde01
Posts: 5
Joined: Sat Oct 19 2019 3:12 pm

CsPaint questions

Post by rconde01 »

Hi

I found many aspects of the CppCon 2019 graphics presentation interesting. I have played with sdf based text rendering and was interesting in testing it with the multi-channel sdf approach...so now you have done it for me!

You focused on the advantages of the multi-channel approach for sharp corners on large fonts. However, I had found in the past that sdf quality also had problems on smaller sizes. High DPI is certainly a concern...but we need/expect good quality for small/normal sizes/non-high-dpi as well. I wanted to play with this in CsPaint but I wasn't able to get a build working quickly on windows due to the dependencies. Can you post a screen shot? Similarly rotated text might be problematic at small/typical sizes.

Here are some other resources you might find interesting:

* Glyphy
** https://github.com/behdad/glyphy, which is by the same guy who does harfbuzz
* https://medium.com/@evanwallace/easy-scalable-text-rendering-on-the-gpu-c3f4d782c5ac
* https://wdobbie.com/post/gpu-text-rendering-with-vector-textures/
* http://jcgt.org/published/0006/02/02/
** This was commercialed into Slug, https://sluglibrary.com/

Regarding your plans to basically use a vulkan backend as the solution to high-dpi, i wonder how you will handle various design elements on scaling. For example, if you have a line which is 1 pixel wide, and then you scale to 1.5, the line will look blurry...so something more nuanced than a naive scaling may be required in some circumstances.

barbara
Posts: 135
Joined: Sat Apr 04 2015 2:32 am

Re: CsPaint questions

Post by barbara »

I wanted to play with this in CsPaint but I wasn't able to get a build working quickly on windows due to the dependencies
I tested CsPaint on Windows, was there a particular dependency you could not find or had issues installing?
Can you post a screen shot?
Can you let us know what you are looking for?

We are using Harfbuzz and have worked with Behdad, he is a wonderful person. Glyphy appears to be similar to our approach, however with our multi channel SDF shaders we have more accurate results than the standard SDF.

Slug is a commercial product which makes it unusable for an open source project. This product does not use SDF but evaluates the Bezier curves in a fragment shader. Not a bad approach however it can be very slow.

In terms of using Vulkan for rendering in CopperSpice, the items you mentioned maybe a concern. However, our approach will be much better than current GUI 2D approaches. These may need to be handled on a per case basis but simply having a user interface which scales properly at non integer scaling factors is fantastic progress.

Thanks for your interest in CsPaint and we look forward to a continued discussion.

Barbara

rconde01
Posts: 5
Joined: Sat Oct 19 2019 3:12 pm

Re: CsPaint questions

Post by rconde01 »

Can you let us know what you are looking for?
Screenshots of your solution rendering fonts at typical/small sizes.

Glyphy is not using regular sdfs...it approximates glyph outlines using circular arcs which is then encoded. It thus suffers no issues from the sampling nature of a texture based sdf. I'm not saying it's the correct solution for you, but thought you'd like to be aware.

Yes slug is commercial, but i linked to the paper/code on which it is based...which is open source (not sure the license however).

My build issues i suppose stemmed from having Cmake find the libraries. It's not really a problem with your build system...it just, unfortunately, the typical case of PITA dependency management in C++ where you have to spend 30-60 mins just to check out a tool...which is why i suggested vcpkg support in another thread. I wasn't trying to say you have a problem there...just explaining why i wanted you to create a screenshot instead of creating it myself, which of course is more ideal.

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