[APP BUG] Some presets look bad on high-dpi display

[joshuakraemer]

Please confirm the following points:

• This report is NOT about the Android apps in the Play Store
• I have searched the project page to check if the issue was already reported

Affected Application

projectM Standalone SDL2 Frontend (includes the Steam app)

Affected Version

2.0-linux-pre2

Operating System

Linux (Desktop)

Additional Application Details

https://github.com/kblaschke/frontend-sdl2/releases/download/2.0-linux-pre2/projectMSDL-2.0.0-Linux-x86_64.deb

Type of Defect

Graphical issue (rendering glitches, black screen, heavy flickering)

Log Output

Describe the Issue

My system runs Xorg. I have a high-dpi display with a resolution of 3840x2160 px and 288 dpi (3x scaling). Some presets look really bad because graphical elements like thin lines are rendered too thin.

Butterchurn seems to account for the system dpi and scale pixel values accordingly (or the scaling might be done by the browser?). Here's a screenshot pf projectM and Butterchurn running side-by-side with the same preset demonstrating the difference:

[kblaschke]

This is basically a duplicate of projectM-visualizer/projectm#682, as this is a known issue in most Milkdrop versions as well.

As of version 4.1, projectM can only render at the native surface resolution, so performing upscaling is currently not easily possible (would need a second window). Once we have released v4.2, which introduces FBO rendering support (AKA render-to-texture), we'll introduce an option to automatically or manually upscale projectM output to the screen resolution (which is also super useful for embedded systems as the Raspberry Pi to improve shader performance).

I keep this issue open until this happened, so you can keep track.