Implement user-specified pixel shaders, redux (#8565)

Co-authored-by: mrange <[email protected]>

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 #7058

Closes #7013

Closes #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.

Author: zadjii-msft

.github/actions/spell-check/dictionary/apis.txt

@@ -8,9 +8,12 @@ cmdletbinding
 COLORPROPERTY
 CXICON
 CYICON
+D2DERR_SHADER_COMPILE_FAILED
+DERR
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 EXPCMDFLAGS
 EXPCMDSTATE
+frac
 fullkbd
 futex
 GETDESKWALLPAPER
@@ -34,7 +37,6 @@ IObject
 IStorage
 ITab
 ITaskbar
-llabs
 LCID
 llabs
 localtime
@@ -64,6 +66,7 @@ semver
 serializer
 shobjidl
 SIZENS
+smoothstep
 GETDESKWALLPAPER
 snprintf
 spsc
@@ -83,6 +86,7 @@ UPDATEINIFILE
 userenv
 wcsstr
 wcstoui
+wpc
 wsregex
 XDocument
 XElement

.github/actions/spell-check/dictionary/names.txt

@@ -12,16 +12,20 @@ ekg
 ethanschoonover
 Firefox
 Gatta
+glsl
 Grie
 Griese
 Hernan
 Howett
 Illhardt
+iquilezles
 jantari
 jerrysh
 Kaiyu
 kimwalisch
 KMehrain
+KODELIFE
+Kodelife
 Kourosh
 kowalczyk
 leonmsft
@@ -30,6 +34,7 @@ lukesampson
 Manandhar
 mbadolato
 Mehrain
+menger
 mgravell
 michaelniksa
 michkap
@@ -43,6 +48,7 @@ nvaccess
 nvda
 oising
 oldnewthing
+opengl
 osgwiki
 paulcam
 pauldotknopf
@@ -51,6 +57,7 @@ Pham
 Rincewind
 rprichard
 Schoonover
+shadertoy
 Somuah
 sonph
 sonpham
@@ -60,8 +67,8 @@ Wirt
 Wojciech
 zadjii
 Zamor
-Zamora
 zamora
+Zamora
 Zoey
 zorio
 Zverovich

.github/actions/spell-check/expect/expect.txt

@@ -24,8 +24,8 @@ ADDREF
 addressof
 ADDSTRING
 ADDTOOL
-AEnd
 aef
+AEnd
 AFew
 AFill
 AFX
@@ -628,6 +628,7 @@ doskey
 dotnet
 doubleclick
 downlevel
+DOWNSCALE
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 dpi
 DPIAPI
@@ -832,6 +833,7 @@ fuzzwrapper
 fwdecl
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 fwlink
+GAUSSIAN
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@@ -909,6 +911,7 @@ Goldmine
 gonce
 Google
 goutput
+GPUs
 Gravell's
 grayscale
 GREENSCROLL
@@ -1109,6 +1112,7 @@ INTERCEPTCOPYPASTE
 INTERNALNAME
 interop
 interoperability
+intersectors
 inthread
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@@ -1207,6 +1211,7 @@ KJ
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 KLMNOPQRST
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+Kode
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@@ -1591,6 +1596,7 @@ OACR
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+ocolor
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@@ -1789,6 +1795,7 @@ pragma
 prc
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+precendence
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@@ -1834,6 +1841,7 @@ pshn
 PSHNOTIFY
 PSHORT
 pshpack
+psin
 PSINGLE
 psl
 psldl
@@ -1882,10 +1890,12 @@ QWER
 qzmp
 RAII
 RALT
+rasterbar
 rasterfont
 rasterization
 rawinput
 RAWPATH
+raytracers
 razzlerc
 rbar
 rbegin
@@ -1956,9 +1966,11 @@ RESETCONTENT
 resheader
 resizable
 resmimetype
+reso
 restrictedcapabilities
 resw
 resx
+RETROII
 retval
 rfa
 rfc
@@ -2029,11 +2041,14 @@ SBCSDBCS
 sbi
 sbiex
 sbold
+sbri
+scanbri
 scancode
 scanline
 schemename
 SCL
 scm
+scol
 scprintf
 SCRBUF
 SCRBUFSIZE
@@ -2167,6 +2182,9 @@ SOURCESDIRECTORY
 SPACEBAR
 spammy
 spand
+spe
+sph
+spherefunctions
 splashscreen
 sprintf
 sqlproj
@@ -2296,6 +2314,7 @@ tellp
 telnet
 telnetd
 templated
+teraflop
 terminalcore
 TERMINALSCROLLING
 terminfo
@@ -2544,6 +2563,7 @@ vga
 vgaoem
 viewkind
 viewports
+Viginetting
 Virt
 VIRTTERM
 Virtualizing
@@ -2760,6 +2780,7 @@ wwaproj
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+wz
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@@ -2809,7 +2830,10 @@ xutr
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+XWV
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+xyw
+Xzn
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@@ -2825,6 +2849,7 @@ YVIRTUALSCREEN
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+yzx
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doc/cascadia/profiles.schema.json

@@ -103,7 +103,7 @@
         "toggleFocusMode",
         "toggleFullscreen",
         "togglePaneZoom",
-        "toggleRetroEffect",
+        "toggleShaderEffects",
         "wt",
         "unbound"
       ],
@@ -936,6 +936,10 @@
           "description": "When set to true, enable retro terminal effects. This is an experimental feature, and its continued existence is not guaranteed.",
           "type": "boolean"
         },
+        "experimental.pixelShaderPath": {
+          "description": "Use to set a path to a pixel shader to use with the Terminal. Overrides `experimental.retroTerminalEffect`. This is an experimental feature, and its continued existence is not guaranteed.",
+          "type": "string"
+        },
         "fontFace": {
           "default": "Cascadia Mono",
           "description": "Name of the font face used in the profile.",

samples/PixelShaders/Broken.hlsl

@@ -0,0 +1,18 @@
+// Broken, can be used for explorative testing of pixel shader error handling
+Texture2D shaderTexture;
+SamplerState samplerState;
+
+cbuffer PixelShaderSettings {
+  float  Time;
+  float  Scale;
+  float2 Resolution;
+  float4 Background;
+};
+
+float4 main(float4 pos : SV_POSITION, float2 tex : TEXCOORD) : SV_TARGET
+{
+    // OOPS; vec4 is not a hlsl but a glsl datatype!
+    vec4 color = shaderTexture.Sample(samplerState, tex);
+
+    return color;
+}

samples/PixelShaders/Error.hlsl

@@ -0,0 +1,18 @@
+// Shader used to indicate something went wrong during shader loading
+Texture2D shaderTexture;
+SamplerState samplerState;
+
+cbuffer PixelShaderSettings {
+  float  Time;
+  float  Scale;
+  float2 Resolution;
+  float4 Background;
+};
+
+float4 main(float4 pos : SV_POSITION, float2 tex : TEXCOORD) : SV_TARGET
+{
+    float4 color = shaderTexture.Sample(samplerState, tex);
+    float bars = 0.5+0.5*sin(tex.y*100);
+    color.x += pow(bars, 20.0);
+    return color;
+}

samples/PixelShaders/Grayscale.hlsl

@@ -0,0 +1,32 @@
+// A minimal pixel shader that inverts the colors
+
+// The terminal graphics as a texture
+Texture2D shaderTexture;
+SamplerState samplerState;
+
+// Terminal settings such as the resolution of the texture
+cbuffer PixelShaderSettings {
+  // Time since pixel shader was enabled
+  float  Time;
+  // UI Scale
+  float  Scale;
+  // Resolution of the shaderTexture
+  float2 Resolution;
+  // Background color as rgba
+  float4 Background;
+};
+
+// A pixel shader is a program that given a texture coordinate (tex) produces a color
+//  Just ignore the pos parameter
+float4 main(float4 pos : SV_POSITION, float2 tex : TEXCOORD) : SV_TARGET
+{
+    // Read the color value at the current texture coordinate (tex)
+    //  float4 is tuple of 4 floats, rgba
+    float4 color = shaderTexture.Sample(samplerState, tex);
+    float avg = (color.x + color.y + color.z) / 3.0;
+    // Inverts the rgb values (xyz) but don't touch the alpha (w)
+    color.xyz = avg;
+
+    // Return the final color
+    return color;
+}

samples/PixelShaders/Invert.hlsl

@@ -0,0 +1,32 @@
+// A minimal pixel shader that inverts the colors
+
+// The terminal graphics as a texture
+Texture2D shaderTexture;
+SamplerState samplerState;
+
+// Terminal settings such as the resolution of the texture
+cbuffer PixelShaderSettings {
+  // Time since pixel shader was enabled
+  float  Time;
+  // UI Scale
+  float  Scale;
+  // Resolution of the shaderTexture
+  float2 Resolution;
+  // Background color as rgba
+  float4 Background;
+};
+
+// A pixel shader is a program that given a texture coordinate (tex) produces a color
+//  Just ignore the pos parameter
+float4 main(float4 pos : SV_POSITION, float2 tex : TEXCOORD) : SV_TARGET
+{
+    // Read the color value at the current texture coordinate (tex)
+    //  float4 is tuple of 4 floats, rgba
+    float4 color = shaderTexture.Sample(samplerState, tex);
+
+    // Inverts the rgb values (xyz) but don't touch the alpha (w)
+    color.xyz = 1.0 - color.xyz;
+
+    // Return the final color
+    return color;
+}