feat(render): implement Campaign AR and terrain fidelity

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

@@ -0,0 +1,90 @@
+using System.Numerics;
+using AcDream.App.Rendering;
+using AcDream.App.Rendering.Gpu;
+
+namespace AcDream.App.Tests.Rendering;
+
+public sealed class RetailDetailTextureContractTests
+{
+    private static readonly TerrainAtlas.RetailDetailTextureBinding Available = new(
+        new GpuTextureSlot(7),
+        Tiling: 4f,
+        SurfaceTextureId: 0x05001787,
+        RenderSurfaceId: 0x06006D58,
+        Width: 256,
+        Height: 256);
+
+    [Fact]
+    public void ExistingBuildingDetailSettingIsTheLivePassGate()
+    {
+        Assert.False(RetailDetailTextureContract.ShouldRender(false, Available));
+        Assert.True(RetailDetailTextureContract.ShouldRender(true, Available));
+        Assert.False(RetailDetailTextureContract.ShouldRender(true, default));
+    }
+
+    [Fact]
+    public void OpaqueDetailUsesDepthEqualityWhileTransparentDetailDoesNot()
+    {
+        Assert.Equal(
+            GpuCompareOp.Equal,
+            RetailDetailTextureContract.DetailDepthCompare(transparent: false));
+        Assert.Equal(
+            GpuCompareOp.LessOrEqual,
+            RetailDetailTextureContract.DetailDepthCompare(transparent: true));
+    }
+
+    [Theory]
+    [InlineData(0f, 1f)]
+    [InlineData(10f, 1f)]
+    [InlineData(30f, 0.5f)]
+    [InlineData(50f, 0f)]
+    [InlineData(80f, 0f)]
+    public void DistanceFadeUsesPositiveViewDepthInMetres(
+        float depthMetres,
+        float expected)
+    {
+        Assert.Equal(
+            expected,
+            RetailDetailTextureContract.FadeForPositiveViewDepthMetres(depthMetres),
+            precision: 5);
+    }
+
+    [Fact]
+    public void FadeZeroIsExactNoOpAndNeutralRgbEqualsAlpha()
+    {
+        var brighteningSample = new Vector4(0.459f, 0.459f, 0.459f, 0.282f);
+        Assert.Equal(
+            Vector3.One,
+            RetailDetailTextureContract.FramebufferFactor(brighteningSample, fade: 0f));
+
+        var neutral = new Vector4(0.4f, 0.4f, 0.4f, 0.4f);
+        Vector3 neutralFactor = RetailDetailTextureContract.FramebufferFactor(neutral, fade: 1f);
+        Assert.Equal(1f, neutralFactor.X, precision: 5);
+        Assert.Equal(1f, neutralFactor.Y, precision: 5);
+        Assert.Equal(1f, neutralFactor.Z, precision: 5);
+    }
+
+    [Fact]
+    public void RetailBlendPreservesMeasuredBrightening()
+    {
+        var measured = new Vector4(0.459f, 0.459f, 0.459f, 0.282f);
+        Vector3 factor = RetailDetailTextureContract.FramebufferFactor(measured, fade: 1f);
+
+        Assert.Equal(1.177f, factor.X, precision: 5);
+        Assert.Equal(1.177f, factor.Y, precision: 5);
+        Assert.Equal(1.177f, factor.Z, precision: 5);
+    }
+
+    [Fact]
+    public void EnabledDerethCategoryTextureKeepsItsMeasuredBrightening()
+    {
+        var derethCategory = new Vector4(0.165f, 0.165f, 0.165f, 0.132f);
+        Vector3 factor = RetailDetailTextureContract.FramebufferFactor(
+            derethCategory,
+            fade: 1f);
+
+        Assert.Equal(1.033f, factor.X, precision: 5);
+        Assert.Equal(1.033f, factor.Y, precision: 5);
+        Assert.Equal(1.033f, factor.Z, precision: 5);
+    }
+}