Fix ADV chrome one-shot blending

engine/Age.Engine.Tests/OneShotColorTests.cs

@@ -35,17 +35,19 @@ public class OneShotColorTests
         gfx.SetAnimatedObjectColorResolved(0x100, 100, 400, 0xff, 0x90a0b0);
 
         var start = gfx.SnapshotVisibleObjects(1000).Single();
-        Assert.Equal(0, start.TintStrength);
+        Assert.Equal(0, start.Alpha);
+        Assert.True(start.MultiplyTint);
         Assert.Equal(0.0, start.ColorTransition!.Value.Progress);
-        Assert.Equal(0, gfx.SnapshotVisibleObjects(1100).Single().TintStrength);
+        Assert.Equal(0, gfx.SnapshotVisibleObjects(1100).Single().Alpha);
 
         var half = gfx.SnapshotVisibleObjects(1300).Single();
-        Assert.Equal(0x7f, half.TintStrength);
+        Assert.Equal(0x7f, half.Alpha);
         Assert.Equal(0x506070, half.Tint);
         Assert.Equal(0.5, half.ColorTransition!.Value.Progress, 3);
 
         var end = gfx.SnapshotVisibleObjects(1500).Single();
-        Assert.Equal(0xff, end.TintStrength);
+        Assert.Equal(0xff, end.Alpha);
+        Assert.True(end.MultiplyTint); // committed endpoints keep the op-0x202 blend contract
         Assert.Equal(0x90a0b0, end.Tint);
         Assert.False(gfx.TryGet(0x100)!.OneShotColorEnabled);
         Assert.Equal(-1, gfx.TryGet(0x100)!.OneShotColorTarget);
@@ -59,10 +61,10 @@ public class OneShotColorTests
         gfx.SetStaticObjectColorResolved(0x100, 0, 0xff, 0xffffff);
 
         var start = gfx.SnapshotVisibleObjects(2000).Single();
-        Assert.Equal(0xff, start.TintStrength);
+        Assert.Equal(0xff, start.Alpha);
         Assert.Equal(0xffffff, start.Tint);
         var half = gfx.SnapshotVisibleObjects(2150).Single();
-        Assert.Equal(0x7f, half.TintStrength);
+        Assert.Equal(0x7f, half.Alpha);
         Assert.Equal(0xffffff, half.Tint);
     }
 
@@ -75,7 +77,7 @@ public class OneShotColorTests
 
         gfx.SnapshotVisibleObjects(5000);
         var half = gfx.SnapshotVisibleObjects(5500).Single();
-        Assert.Equal(0x7f, half.TintStrength);
+        Assert.Equal(0x7f, half.Alpha);
         Assert.Equal(1.5, half.Transform.ScaleX, 3);
         Assert.Equal(5000, half.ColorTransition!.Value.StartMs);
     }

engine/Age.Engine.Tests/RenderObjectBlendTests.cs

@@ -77,6 +77,21 @@ public class RenderObjectBlendTests
         Assert.Equal(BlendKind.Alpha, ro.Blend);
     }
 
+    [Fact]
+    public void Mode0_OneShotColor_UsesOpacityAndMultiplicativeRgbAfterCommit()
+    {
+        var g = WithVisibleObject(0x100, resId: 5, colorKey: -1);
+        g.SetAnimatedObjectColorResolved(0x100, 0, 100, 0x00, 0xffffff);
+        g.SetStaticObjectColorResolved(0x100, 0, 0xff, 0xffffff);
+
+        g.SnapshotVisibleObjects(1000); // seed
+        var hidden = g.SnapshotVisibleObjects(1100).Single();
+        Assert.Equal(0, hidden.Alpha);
+        Assert.Equal(0, hidden.TintStrength);
+        Assert.True(hidden.MultiplyTint);
+        Assert.False(g.TryGet(0x100)!.OneShotColorEnabled);
+    }
+
     [Fact]
     public void ColorKey_IsCarriedThrough()
     {

engine/Age.Engine.Tests/SoftwareAffineRasterizerTests.cs

@@ -40,4 +40,20 @@ public class SoftwareAffineRasterizerTests
         Assert.InRange(dst[2], 5, 7);
         Assert.InRange(dst[3], 126, 127);
     }
+
+    [Fact]
+    public void BlitRgba_WhiteModulationPreservesYellowAndZeroOpacityHidesIt()
+    {
+        byte[] src = { 240, 192, 16, 255 };
+        byte[] visible = new byte[4];
+        var identity = new Affine2D(1, 0, 0, 1, 0, 0);
+        SoftwareAffineRasterizer.BlitRgba(visible, 1, 1, src, 1, 1, 0, 0, 1, 1,
+            identity, 0xffffff, 0, 1, multiplyTint: true);
+        Assert.Equal(new byte[] { 240, 192, 16, 255 }, visible);
+
+        byte[] hidden = new byte[4];
+        SoftwareAffineRasterizer.BlitRgba(hidden, 1, 1, src, 1, 1, 0, 0, 1, 1,
+            identity, 0xffffff, 0, 0, multiplyTint: true);
+        Assert.Equal(new byte[4], hidden);
+    }
 }