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Sharp-Bilinear Shaders for Retroarch v1.4
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@rsn8887 rsn8887 released this 18 Aug 22:52
· 10 commits to master since this release
1.4
440f8b8

Sharp-Bilinear Shaders for Retroarch

This is a collection of shaders for sharp pixels without pixel wobble and minimal blurring in RetroArch/Libretro.

There are two shaders included.

  • "2x-prescale-sharp-bilinear"

This shader does a fixed 2x integer prescale resulting in a small amount of image blurring but no pixelwobble. This is a simple two-pass shader configuration. First, an integer 2x prescale is applied, followed by a bilinear scaling to fullscreen.

  • "sharp-bilinear-simple"

This shader does an automatic optimum integer prescale (2x, 3x, 4x etc.), depending on game and screen resolution. I recommend this shader since the autoscaling results in sharper images for some games than the fixed 2x prescale.

Both shader configurations give sharp pixels with zero pixel wobble in all games.

Compared to the "video smoothing=ON" setting with no shaders, pixels are less blurry. Compared to the "video smoothing=OFF" setting with no shaders, the pixels do not change shape/wobble as they move across the screen.

I tried TheMaister's autoscaling shader from the libretro repo, "retro/sharp-bilinear.glslp," but, for some reason, that shader did not work well with vertical games for me.

Installation

To install this shader in RetroPie:

  • Copy the contents of the included "Copy_To_RetroPie" folder to /opt/retropie/emulators/retroarch/shader/
  • open the RetroPie-Setup menu and choose "Edit RetroPie/RetroArch Configurations"-> "configure basic libretro emulator options"-> "configure default options for all libretro emulators"
  • set "Video Shader Enable" to "True"
  • set "Video Shader File" to "sharp-bilinear-simple.glslp," or "2x-prescale-sharp-bilinear.glslp" depending on your preference.

Example Images

shader "sharp-bilinear-simple.glslp" on:

shader off, smoothing on (too much blur):

shader off, smoothing off:

On first glance, the above looks sharp and good, but looking at a detail, we can see pixel wobble that happens if no shader is used. The pixels along the black diagonal should all be the same, square shape, but some of them appear rectangular:

Compare the above detail to the result with the shader on:

Now all pixels have the same shape, at the cost of a slight reduction in sharpness.

Changelog

1.4

  • fixed sharp-bilinear-simple, it only worked on Windows but not on Raspberry Pi

1.3

  • added sharp-bilinear-simple shader with autoscale

1.2

  • Initial release of 2x-prescale-sharp-bilinear
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