Add area sampling scaler to allow for super-sampled anti-aliasing. (#7304)

* Add area sampling scaler to allow for super-sampled anti-aliasing.

* Area scaling filter doesn't have a scaling level.

* Add further clarification to the tooltip on how to achieve supersampling.

* ShaderHelper: Merge the two CompileProgram functions.

* Convert tabs to spaces in area scaling shaders

* Fixup Vulkan and OpenGL project files.

* AreaScaling: Replace texture() by texelFetch() and use integer vectors.

No functional difference, but it cleans up the code a bit.

* AreaScaling: Delete unused sharpening level member.

Also rename _scale to _sharpeningLevel for clarity and consistency.

* AreaScaling: Delete unused scaleX/scaleY uniforms.

* AreaScaling: Force the alpha to 1 when storing the pixel.

* AreaScaling: Remove left-over sharpening buffer.

5 files changed, 231 insertions, 0 deletions

diff --git a/src/Ryujinx.Graphics.Vulkan/Effects/AreaScalingFilter.cs b/src/Ryujinx.Graphics.Vulkan/Effects/AreaScalingFilter.cs
new file mode 100644
index 00000000..87b46df8
--- /dev/null
+++ b/src/Ryujinx.Graphics.Vulkan/Effects/AreaScalingFilter.cs
@@ -0,0 +1,101 @@
+using Ryujinx.Common;
+using Ryujinx.Graphics.GAL;
+using Ryujinx.Graphics.Shader;
+using Ryujinx.Graphics.Shader.Translation;
+using Silk.NET.Vulkan;
+using System;
+using Extent2D = Ryujinx.Graphics.GAL.Extents2D;
+using Format = Silk.NET.Vulkan.Format;
+using SamplerCreateInfo = Ryujinx.Graphics.GAL.SamplerCreateInfo;
+
+namespace Ryujinx.Graphics.Vulkan.Effects
+{
+    internal class AreaScalingFilter : IScalingFilter
+    {
+        private readonly VulkanRenderer _renderer;
+        private PipelineHelperShader _pipeline;
+        private ISampler _sampler;
+        private ShaderCollection _scalingProgram;
+        private Device _device;
+
+        public float Level { get; set; }
+
+        public AreaScalingFilter(VulkanRenderer renderer, Device device)
+        {
+            _device = device;
+            _renderer = renderer;
+
+            Initialize();
+        }
+
+        public void Dispose()
+        {
+            _pipeline.Dispose();
+            _scalingProgram.Dispose();
+            _sampler.Dispose();
+        }
+
+        public void Initialize()
+        {
+            _pipeline = new PipelineHelperShader(_renderer, _device);
+
+            _pipeline.Initialize();
+
+            var scalingShader = EmbeddedResources.Read("Ryujinx.Graphics.Vulkan/Effects/Shaders/AreaScaling.spv");
+
+            var scalingResourceLayout = new ResourceLayoutBuilder()
+                .Add(ResourceStages.Compute, ResourceType.UniformBuffer, 2)
+                .Add(ResourceStages.Compute, ResourceType.TextureAndSampler, 1)
+                .Add(ResourceStages.Compute, ResourceType.Image, 0, true).Build();
+
+            _sampler = _renderer.CreateSampler(SamplerCreateInfo.Create(MinFilter.Linear, MagFilter.Linear));
+
+            _scalingProgram = _renderer.CreateProgramWithMinimalLayout(new[]
+            {
+                new ShaderSource(scalingShader, ShaderStage.Compute, TargetLanguage.Spirv),
+            }, scalingResourceLayout);
+        }
+
+        public void Run(
+            TextureView view,
+            CommandBufferScoped cbs,
+            Auto<DisposableImageView> destinationTexture,
+            Format format,
+            int width,
+            int height,
+            Extent2D source,
+            Extent2D destination)
+        {
+            _pipeline.SetCommandBuffer(cbs);
+            _pipeline.SetProgram(_scalingProgram);
+            _pipeline.SetTextureAndSampler(ShaderStage.Compute, 1, view, _sampler);
+
+            ReadOnlySpan<float> dimensionsBuffer = stackalloc float[]
+            {
+                source.X1,
+                source.X2,
+                source.Y1,
+                source.Y2,
+                destination.X1,
+                destination.X2,
+                destination.Y1,
+                destination.Y2,
+            };
+
+            int rangeSize = dimensionsBuffer.Length * sizeof(float);
+            using var buffer = _renderer.BufferManager.ReserveOrCreate(_renderer, cbs, rangeSize);
+            buffer.Holder.SetDataUnchecked(buffer.Offset, dimensionsBuffer);
+
+            int threadGroupWorkRegionDim = 16;
+            int dispatchX = (width + (threadGroupWorkRegionDim - 1)) / threadGroupWorkRegionDim;
+            int dispatchY = (height + (threadGroupWorkRegionDim - 1)) / threadGroupWorkRegionDim;
+
+            _pipeline.SetUniformBuffers(stackalloc[] { new BufferAssignment(2, buffer.Range) });
+            _pipeline.SetImage(0, destinationTexture);
+            _pipeline.DispatchCompute(dispatchX, dispatchY, 1);
+            _pipeline.ComputeBarrier();
+
+            _pipeline.Finish();
+        }
+    }
+}
diff --git a/src/Ryujinx.Graphics.Vulkan/Effects/Shaders/AreaScaling.glsl b/src/Ryujinx.Graphics.Vulkan/Effects/Shaders/AreaScaling.glsl
new file mode 100644
index 00000000..e34dd77d
--- /dev/null
+++ b/src/Ryujinx.Graphics.Vulkan/Effects/Shaders/AreaScaling.glsl
@@ -0,0 +1,122 @@
+// Scaling
+
+#version 430 core
+layout (local_size_x = 16, local_size_y = 16) in;
+layout( rgba8, binding = 0, set = 3) uniform image2D imgOutput;
+layout( binding = 1, set = 2) uniform sampler2D Source;
+layout( binding = 2 ) uniform dimensions{
+ float srcX0;
+ float srcX1;
+ float srcY0;
+ float srcY1;
+ float dstX0;
+ float dstX1;
+ float dstY0;
+ float dstY1;
+};
+
+/***** Area Sampling *****/
+
+// By Sam Belliveau and Filippo Tarpini. Public Domain license.
+// Effectively a more accurate sharp bilinear filter when upscaling,
+// that also works as a mathematically perfect downscale filter.
+// https://entropymine.com/imageworsener/pixelmixing/
+// https://github.com/obsproject/obs-studio/pull/1715
+// https://legacy.imagemagick.org/Usage/filter/
+vec4 AreaSampling(vec2 xy)
+{
+    // Determine the sizes of the source and target images.
+    vec2 source_size = vec2(abs(srcX1 - srcX0), abs(srcY1 - srcY0));
+    vec2 target_size = vec2(abs(dstX1 - dstX0), abs(dstY1 - dstY0));
+    vec2 inverted_target_size = vec2(1.0) / target_size;
+
+    // Compute the top-left and bottom-right corners of the target pixel box.
+    vec2 t_beg = floor(xy - vec2(dstX0 < dstX1 ? dstX0 : dstX1, dstY0 < dstY1 ? dstY0 : dstY1));
+    vec2 t_end = t_beg + vec2(1.0, 1.0);
+
+    // Convert the target pixel box to source pixel box.
+    vec2 beg = t_beg * inverted_target_size * source_size;
+    vec2 end = t_end * inverted_target_size * source_size;
+
+    // Compute the top-left and bottom-right corners of the pixel box.
+    ivec2 f_beg = ivec2(beg);
+    ivec2 f_end = ivec2(end);
+
+    // Compute how much of the start and end pixels are covered horizontally & vertically.
+    float area_w = 1.0 - fract(beg.x);
+    float area_n = 1.0 - fract(beg.y);
+    float area_e = fract(end.x);
+    float area_s = fract(end.y);
+
+    // Compute the areas of the corner pixels in the pixel box.
+    float area_nw = area_n * area_w;
+    float area_ne = area_n * area_e;
+    float area_sw = area_s * area_w;
+    float area_se = area_s * area_e;
+
+    // Initialize the color accumulator.
+    vec4 avg_color = vec4(0.0, 0.0, 0.0, 0.0);
+
+    // Accumulate corner pixels.
+    avg_color += area_nw * texelFetch(Source, ivec2(f_beg.x, f_beg.y), 0);
+    avg_color += area_ne * texelFetch(Source, ivec2(f_end.x, f_beg.y), 0);
+    avg_color += area_sw * texelFetch(Source, ivec2(f_beg.x, f_end.y), 0);
+    avg_color += area_se * texelFetch(Source, ivec2(f_end.x, f_end.y), 0);
+
+    // Determine the size of the pixel box.
+    int x_range = int(f_end.x - f_beg.x - 0.5);
+    int y_range = int(f_end.y - f_beg.y - 0.5);
+
+    // Accumulate top and bottom edge pixels.
+    for (int x = f_beg.x + 1; x <= f_beg.x + x_range; ++x)
+    {
+        avg_color += area_n * texelFetch(Source, ivec2(x, f_beg.y), 0);
+        avg_color += area_s * texelFetch(Source, ivec2(x, f_end.y), 0);
+    }
+
+    // Accumulate left and right edge pixels and all the pixels in between.
+    for (int y = f_beg.y + 1; y <= f_beg.y + y_range; ++y)
+    {
+        avg_color += area_w * texelFetch(Source, ivec2(f_beg.x, y), 0);
+        avg_color += area_e * texelFetch(Source, ivec2(f_end.x, y), 0);
+
+        for (int x = f_beg.x + 1; x <= f_beg.x + x_range; ++x)
+        {
+            avg_color += texelFetch(Source, ivec2(x, y), 0);
+        }
+    }
+
+    // Compute the area of the pixel box that was sampled.
+    float area_corners = area_nw + area_ne + area_sw + area_se;
+    float area_edges = float(x_range) * (area_n + area_s) + float(y_range) * (area_w + area_e);
+    float area_center = float(x_range) * float(y_range);
+
+    // Return the normalized average color.
+    return avg_color / (area_corners + area_edges + area_center);
+}
+
+float insideBox(vec2 v, vec2 bLeft, vec2 tRight) {
+    vec2 s = step(bLeft, v) - step(tRight, v);
+    return s.x * s.y;
+}
+
+vec2 translateDest(vec2 pos) {
+    vec2 translatedPos = vec2(pos.x, pos.y);
+    translatedPos.x = dstX1 < dstX0 ? dstX1 - translatedPos.x : translatedPos.x;
+    translatedPos.y = dstY0 < dstY1 ? dstY1 + dstY0 - translatedPos.y - 1 : translatedPos.y;
+    return translatedPos;
+}
+
+void main()
+{
+    vec2 bLeft = vec2(dstX0 < dstX1 ? dstX0 : dstX1, dstY0 < dstY1 ? dstY0 : dstY1);
+    vec2 tRight = vec2(dstX1 > dstX0 ? dstX1 : dstX0, dstY1 > dstY0 ? dstY1 : dstY0);
+    ivec2 loc = ivec2(gl_GlobalInvocationID.x, gl_GlobalInvocationID.y);
+    if (insideBox(loc, bLeft, tRight) == 0) {
+        imageStore(imgOutput, loc, vec4(0, 0, 0, 1));
+        return;
+    }
+
+    vec4 outColor = AreaSampling(loc);
+    imageStore(imgOutput, ivec2(translateDest(loc)), vec4(outColor.rgb, 1));
+}
diff --git a/src/Ryujinx.Graphics.Vulkan/Effects/Shaders/AreaScaling.spv b/src/Ryujinx.Graphics.Vulkan/Effects/Shaders/AreaScaling.spv
new file mode 100644
index 00000000..7d097280
--- /dev/null
+++ b/src/Ryujinx.Graphics.Vulkan/Effects/Shaders/AreaScaling.spv
diff --git a/src/Ryujinx.Graphics.Vulkan/Ryujinx.Graphics.Vulkan.csproj b/src/Ryujinx.Graphics.Vulkan/Ryujinx.Graphics.Vulkan.csproj
index f6a7be91..aae28733 100644
--- a/src/Ryujinx.Graphics.Vulkan/Ryujinx.Graphics.Vulkan.csproj
+++ b/src/Ryujinx.Graphics.Vulkan/Ryujinx.Graphics.Vulkan.csproj
@@ -15,6 +15,7 @@
   <ItemGroup>
     <EmbeddedResource Include="Effects\Textures\SmaaAreaTexture.bin" />
     <EmbeddedResource Include="Effects\Textures\SmaaSearchTexture.bin" />
+    <EmbeddedResource Include="Effects\Shaders\AreaScaling.spv" />
     <EmbeddedResource Include="Effects\Shaders\FsrScaling.spv" />
     <EmbeddedResource Include="Effects\Shaders\FsrSharpening.spv" />
     <EmbeddedResource Include="Effects\Shaders\Fxaa.spv" />
diff --git a/src/Ryujinx.Graphics.Vulkan/Window.cs b/src/Ryujinx.Graphics.Vulkan/Window.cs
index d67362be..3dc6d4e1 100644
--- a/src/Ryujinx.Graphics.Vulkan/Window.cs
+++ b/src/Ryujinx.Graphics.Vulkan/Window.cs
@@ -568,6 +568,13 @@ namespace Ryujinx.Graphics.Vulkan
 
                         _scalingFilter.Level = _scalingFilterLevel;
                         break;
+                    case ScalingFilter.Area:
+                        if (_scalingFilter is not AreaScalingFilter)
+                        {
+                            _scalingFilter?.Dispose();
+                            _scalingFilter = new AreaScalingFilter(_gd, _device);
+                        }
+                        break;
                 }
             }
         }