Add noise to blur shaders#1518
Conversation
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wow, thanks. this is a very interesting effect. i haven't read your code yet, just wondering, does this have to be tied with blur? can this be a separate effect by itself? seems like it works a lot better with box blur than with dual-kawase? |
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It could be done separately from the blur effect, but that seems like it would complicate the implementation since the non-blur case would have to handle the distortion either in the window shader or in a separate render command (but in that case I'd have to duplicate some of the back buffer code from blur). I didn't think there would be much use for this without any blur, so I didn't try to figure that out. The effect is more subtle in the dual_kawase sample because the blur is more uniform with that configuration. Here's what it looks like with a different configuration (strength=4, noise-radius=80, noise-scale=0.05): 
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A base struct is defined for arguments common to all blur methods. The create_blur_context interface method is changed to accept a pointer to the base type instead of a void pointer. It can't be a pointer-to-const because generate_dual_kawase_params may modify it. Changelog: Internal: Breaking changes to backend API: a `base` field of type `struct blur_args` is added to each blur args struct; the interface method `create_blur_context` now accepts `struct blur_args *` instead of `void *`.
Blur noise options are currently unused. Changelog: NewFeature: `--blur-noise-radius` and `--blur-noise-scale` global options are added for noise configuration. Changelog: NewFeature: `noise-radius` and `noise-scale` options are added to the `blur` configuration section.
ctx is not used after it is set to NULL.
The extension string is always empty when building the kernel blur shader.
This change is needed to apply noise with kernel blur, which requires normalized texture coordinates in the final pass. It is no longer necessary to track the presence of the pixel_norm uniform, since all passes now use it.
Two new uniforms are defined for noise configuration. They are currently unused. This also corrects an off-by-one error in NUMBER_OF_UNIFORMS.
If configured, noise displaces texture coordinates when sampling a blurred window background with any blur method. This can be used to create a rippled (low scale) or frosted glass (high scale) effect. The radius of the noise limits the displacement amount. This allows only features within the radius to contribute to the distorted background. Noise is only implemented for the OpenGL backend, and is only enabled when a blur method is configured. Noise is not applied to shadows. The Simplex noise implementation uses MIT-licensed shader code from Ashima Arts. See https://github.com/stegu/webgl-noise Changelog: NewFeature: Blur noise is implemented for the OpenGL backend.
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force pushed to fix coding style, otherwise LGTM. |
This patch series adds noise to blur shaders that can be used to create a frosted glass effect.
Noise can be configured using the
--blur-noise-radiusand--blur-noise-scaleoptions, or in theblursection of the configuration file:Closes #1015
Comparison
dual_kawase blur (strength=16, noise-radius=80, noise-scale=0.5):
3x3 box blur with various noise-radius/noise-scale values: