GPU performance VS different texture sizes

Hey everyone!

I am wondering:

If, for a material, I am using
- a 2048px texture (Tex1)
- a 1024px texture (Tex2) that performs calculations using the 2048px texture (let's say col = Tex1 + Tex2),
will using a 1024px texture for Tex2 only reduce RAM usage?
Or will it impact GPU frame time? If so, positively or negatively?

First thought would be less pixels, less calculations, less frame time.
Then again, the 1024px texture may have to be upscaled per frame (?) and result in more calculations than when using a 2048px texture for Tex2.

Best wishes,
Shu

 

Thanks for your reply! Interesting! Including the compression topic! - I was actually thinking compression would reduce RAM usage but decrease performance due to constant decompression. And I also think I read something like that some time ago, but I guess that was about audio files, which probably use quite different procedures. I sure will read more on texture filtering!

 

Thanks for the reply and the additional information! Very interesting!
Now that I think about the actual shader code, it does make sense that this is not a texture size issue, since when doing calculations, you don't use the texture pixels to work with, but pixels on screen instead.

I'm not sure that's going to be the case for my game, since I am not going to use that many texture sets per material, so I should get away with somewhat manageable memory usage. On the other hand, when available, I will probably see if I can get some more content on screen that uses the available memory. I do, however, plan on using quite a number of particles via VFX graph and some compute shaders (e.g. for flocking), if supported by the target platform. But that's going to be a late decision, since in that case, VFX quality can be scaled rather easily.

That for sure! Also, not all formats are supported on each platform. That said, I did see some quite convincing results using crunch compression, depending on the texture. Some did keep visual quality quite well while reducing storage usage and read time from disk drastically. As far as I remember, though, crunch was the least supported one. But that's quite a while ago when I read about that, with current hardware (e.g. Nintendo Switch, PS4, PS5), it may be quite different.

 

Crunch does not reduce RAM usage. A Crunched DXT1 uses the same amount of RAM on the GPU as a regular DXT1. It actually takes slightly more RAM on the CPU, at least when initially loaded. The difference is the Crunch format takes up less space in the build prior to loading, and can load from disk slightly faster.

 

Thanks for the reply! You're absolutely right. I corrected that, but I guess I wasn't fast enough!

 

@aleksandrk
I know its quite old thread, but there is something I never could find any information regard it, does Texture DPI has any impact on performance/memory usuage?

Is 72Dpi image will be treated the same way as 300Dpi image?

Thank you

 

Yeah I'm sure about that, the DPI is usually used for printing and has nothing to do with how unity process image files on GPU as far as I'm concern, thats why I wanted to double check with you to be sure

Thank you so much)

 

@aleksandrk
Sorry to annoy you one last time

Same concept apply for images that are imported as sprites , bec unity anyway convert them to meshes on canvas and DPI of the image has nothing to do with the images being rendered on canvas. Right?

 

I don't think sprites or textures use the DPI in the image's metadata, but there is something similar to DPI for sprites called Pixels Per Unit. This can be used to control how large sprites are on a UI element.

For instance, if some of your sprites are 16x16 and have the default Pixels Per Unit of 100 and and want your 32x32 pixel sprites to appear the same size, then you'd set their Pixels Per Unit value to 200.

 

Yeah I'm aware about this one, but unlike DPI, PPU are set inside unity but DPI is set while exporting the original assets.... so what I want to be sure that the DPI of the image has nothing to do with how unity render UI elements)

 

Texture DPI is 100% ignored at all times for games. The Unity texture importer or asset class doesn’t even access or store that data.

Mobile platforms have a concept of DPI for resolution scaling or UI, but that’s for scaling things like buttons or similar touch interfaces and oddly less about textures.