<!-- Enter a brief description/summary of your PR here. What does it fix/what does it change/how was it tested (even manually, if necessary)? -->
## Summary of the Pull Request
- Adds two simple animated shaders to the pixel shaders sample folder
- Updates the readme in the pixel shaders sample folder to add a section explaining the animated shaders
- Modifies some comments in existing shader samples
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## PR Checklist
* [ ] Closes #xxx
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [ ] Tests added/passed
* [ ] Documentation updated. If checked, please file a pull request on [our docs repo](https://github.com/MicrosoftDocs/terminal) and link it here: #xxx
* [ ] Schema updated.
* [x] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #8994
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## Detailed Description of the Pull Request / Additional comments
The two shaders I wrote are not especially pretty or interesting, but they should hopefully serve as simple examples for anyone looking to do animated effects. One simply draws a line of inverted pixels that scrolls down the screen, and the other fades the background back and forth between two colors.
I've added a new section to the readme explaining how the shaders work to achieve animated effects.
I've also updated the comments on the existing shaders to clear up a couple of things:
1. Be more explicit that `Time` represents seconds since the shader loaded. Though obvious in hindsight, this was not clear to me when I was first learning/experimenting
2. Explain that `tex` ranges from 0,0 to 1,1. This is important because, when trying to port GLSL shaders from shadertoy, I at first assumed `fragCoord` and `tex` are the same thing but the former actually ranges from 0,0 to the resolution of the canvas, so some of the math doesn't work out if you just substitute it with `tex`.
Any and all feedback welcome.
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## Validation Steps Performed
I ran the shaders manually in a dev build of the Terminal. I auto-spellchecked and manually proofread my additions to the readme and verifed the markdown rendering on github.
Co-authored-by: mrange <marten_range@hotmail.com>
I loved the pixel shaders in #7058, but that PR needed a bit of polish
to be ready for ingestion. This PR is almost _exactly_ that PR, with
some small changes.
* It adds a new pre-profile setting `"experimental.pixelShaderPath"`,
which lets the user set a pixel shader to use with the Terminal.
- CHANGED FROM #7058: It does _not_ add any built-in shaders.
- CHANGED FROM #7058: it will _override_
`experimental.retroTerminalEffect`
* It adds a bunch of sample shaders in `samples/shaders`. Included:
- A NOP shader as a base to build from.
- An "invert" shader that inverts the colors, as a simple example
- An "grayscale" shader that converts all colors to grayscale, as a
simple example
- An "raster bars" shader that draws some colored bars on the screen
with a drop shadow, as a more involved example
- The original retro terminal effects, as a more involved example
- It also includes a broken shader, as an example of what heppens
when the shader fails to compile
- CHANGED FROM #7058: It does _not_ add the "retroII" shader we were
all worried about.
* When a shader fails to be found or fails to compile, we'll display an
error dialog to the user with a relevant error message.
- CHANGED FROM #7058: Originally, #7058 would display "error bars"
on the screen. I've removed that, and had the Terminal disable the
shader entirely then.
* Renames the `toggleRetroEffect` action to `toggleShaderEffect`.
(`toggleRetroEffect` is now an alias to `toggleShaderEffect`). This
action will turn the shader OR the retro effects on/off.
`toggleShaderEffect` works the way you'd expect it to, but the mental
math on _how_ is a little weird. The logic is basically:
```
useShader = shaderEffectsEnabled ?
(pixelShaderProvided ?
pixelShader :
(retroEffectEnabled ?
retroEffect : null
)
) :
null
```
and `toggleShaderEffect` toggles `shaderEffectsEnabled`.
* If you've got both a shader and retro enabled, `toggleShaderEffect`
will toggle between the shader on/off.
* If you've got a shader and retro disabled, `toggleShaderEffect` will
toggle between the shader on/off.
References #6191
References #7058Closes#7013Closes#3930 "Add setting to retro terminal shader to control blur
radius, color"
Closes#3929 "Add setting to retro terminal shader to enable drawing
scanlines"
- At this point, just roll your own version of the shader.
Lachlan Picking
Mike Griese