feat(render): implement Campaign AR and terrain fidelity

tests/AcDream.App.Tests/Rendering/DirectionalShadowReceiverTests.cs

@@ -0,0 +1,137 @@
+using System.Numerics;
+using AcDream.App.Rendering;
+
+namespace AcDream.App.Tests.Rendering;
+
+public sealed class DirectionalShadowReceiverTests
+{
+    [Theory]
+    [InlineData("atmospheric-world-hdr", false, true, false)]
+    [InlineData("atmospheric-world-hdr", true, false, false)]
+    [InlineData("vk-world", true, true, false)]
+    [InlineData("atmospheric-world-hdr", true, true, true)]
+    internal void RetailPipelineRemainsExactUnlessPackAndCurrentBindingAreActive(
+        string pass,
+        bool source,
+        bool binding,
+        bool expected) =>
+        Assert.Equal(
+            expected,
+            DirectionalShadowReceiverPolicy.ShouldSelectReceiverPipeline(
+                pass,
+                source,
+                binding));
+
+    [Fact]
+    public void CascadeTransition_IsContinuousAcrossTheSplitInWorldMetres()
+    {
+        Vector4 splits = new(10f, 30f, 60f, 100f);
+
+        DirectionalShadowCascadeBlend atSplit =
+            DirectionalShadowReceiverPolicy.SelectCascade(10f, splits, 4, 2f);
+        DirectionalShadowCascadeBlend afterSplit =
+            DirectionalShadowReceiverPolicy.SelectCascade(10.0001f, splits, 4, 2f);
+
+        Assert.Equal(0, atSplit.PrimaryCascade);
+        Assert.Equal(1, atSplit.SecondaryCascade);
+        Assert.Equal(1f, atSplit.SecondaryWeight, 5);
+        Assert.Equal(1, afterSplit.PrimaryCascade);
+        Assert.Equal(2, afterSplit.SecondaryCascade);
+        Assert.InRange(afterSplit.SecondaryWeight, 0f, 0.00001f);
+        Assert.True(atSplit.WithinShadowReach);
+        Assert.True(afterSplit.WithinShadowReach);
+    }
+
+    [Fact]
+    public void CascadeSelection_StopsAtConfiguredReach()
+    {
+        DirectionalShadowCascadeBlend outside =
+            DirectionalShadowReceiverPolicy.SelectCascade(
+                100.01f,
+                new Vector4(10f, 30f, 60f, 100f),
+                4,
+                2f);
+
+        Assert.False(outside.WithinShadowReach);
+        Assert.Equal(3, outside.PrimaryCascade);
+    }
+
+    [Fact]
+    public void BiasRemainsWorldMetresAndScalesWithSurfaceSlope()
+    {
+        var bias = new DirectionalShadowWorldBias(0.01f, 0.04f, 0.02f);
+
+        Assert.Equal(0.01f, DirectionalShadowReceiverPolicy.ReceiverBiasMeters(bias, 1f), 6);
+        Assert.Equal(0.05f, DirectionalShadowReceiverPolicy.ReceiverBiasMeters(bias, 0f), 6);
+    }
+
+    [Theory]
+    [InlineData(true, false, true, true)]
+    [InlineData(true, true, true, false)]
+    [InlineData(true, false, false, false)]
+    [InlineData(false, false, true, false)]
+    internal void IndoorAndMissingDirectionalTermsNeverSample(
+        bool binding,
+        bool indoor,
+        bool directional,
+        bool expected) =>
+        Assert.Equal(
+            expected,
+            DirectionalShadowReceiverPolicy.ShouldSample(
+                binding,
+                indoor,
+                directional));
+
+    [Fact]
+    public void ReceiverShadersPreserveAnimatedFoliageMaterialAndTransparencySemantics()
+    {
+        string root = RepositoryRoot();
+        string shaderRoot = Path.Combine(
+            root,
+            "src", "AcDream.App", "Rendering", "Shaders");
+        string vertex = File.ReadAllText(Path.Combine(shaderRoot, "mesh_atmospheric.vert"));
+        string fragment = File.ReadAllText(Path.Combine(shaderRoot, "mesh_atmospheric.frag"));
+        string terrain = File.ReadAllText(Path.Combine(shaderRoot, "terrain_atmospheric.frag"));
+        string receiver = File.ReadAllText(Path.Combine(
+            shaderRoot,
+            "directional_shadow_receiver.glsl"));
+
+        Assert.Contains("int transformIndex = gl_BaseInstanceARB + gl_InstanceID", vertex, StringComparison.Ordinal);
+        Assert.Contains("int instanceIndex = transformIndex - int(uTextureIndexB)", vertex, StringComparison.Ordinal);
+        Assert.Contains("Instances[transformIndex].transform", vertex, StringComparison.Ordinal);
+        Assert.Contains("instanceIndoor[instanceIndex]", vertex, StringComparison.Ordinal);
+        Assert.Contains("vSelectionLighting", fragment, StringComparison.Ordinal);
+        Assert.Contains("vOpacityMultiplier", fragment, StringComparison.Ordinal);
+        Assert.Contains("if (color.a < 0.05) discard", fragment, StringComparison.Ordinal);
+        Assert.Contains("ACDREAM_SAMPLE_ARRAY", fragment, StringComparison.Ordinal);
+        Assert.Contains("combineOverlays", terrain, StringComparison.Ordinal);
+        Assert.Contains("combineRoad", terrain, StringComparison.Ordinal);
+        Assert.Contains("smoothstep", receiver, StringComparison.Ordinal);
+        Assert.Contains("acdreamShadowBiasScale(cascade)", receiver, StringComparison.Ordinal);
+        Assert.Contains("textureGather", receiver, StringComparison.Ordinal);
+        Assert.Contains("acdreamShadowBilinearCompare", receiver, StringComparison.Ordinal);
+        Assert.Contains("float weight = float(2 - abs(x))", receiver, StringComparison.Ordinal);
+        Assert.Contains("float reachFade = 1.0 - smoothstep", receiver, StringComparison.Ordinal);
+        Assert.Contains("radius = clamp(radius, 0, 2)", receiver, StringComparison.Ordinal);
+        Assert.Contains("float softness = max(uShadowControl.y, 1.0)", receiver, StringComparison.Ordinal);
+
+        string detailVertex = File.ReadAllText(Path.Combine(
+            shaderRoot,
+            "mesh_detail.vert"));
+        Assert.Contains("int instanceIndex = transformIndex - int(uTextureIndexB)", detailVertex, StringComparison.Ordinal);
+        Assert.Contains("Instances[transformIndex].transform", detailVertex, StringComparison.Ordinal);
+        Assert.Contains("instanceDetailCategory[instanceIndex]", detailVertex, StringComparison.Ordinal);
+    }
+
+    private static string RepositoryRoot()
+    {
+        var directory = new DirectoryInfo(AppContext.BaseDirectory);
+        while (directory is not null
+            && !File.Exists(Path.Combine(directory.FullName, "AcDream.slnx")))
+        {
+            directory = directory.Parent;
+        }
+        return directory?.FullName
+            ?? throw new InvalidOperationException("Could not locate repository root.");
+    }
+}