Fix AE001H spritesheet animation

engine/Age.Engine.Tests/AnimChannelTests.cs

@@ -62,7 +62,8 @@ public class AnimChannelTests
         vm.Run();
         var o = vm.Gfx.TryGet(0x1000)!;
         Assert.True(o.SrcAnim);
-        Assert.Equal(4, o.SrcGridW);
+        Assert.Equal(4, o.SrcFrameCount);
+        Assert.Equal(1, o.SrcColumns);
         Assert.Equal(2, o.SrcCell);
     }
 
@@ -78,9 +79,9 @@ public class AnimChannelTests
     public void SetSrcRect_StoresGridCellPeriod()
     {
         var g = VisibleObj(0x100);
-        g.SetSrcRect(0x100, gridW: 4, gridH: 1, cell: 2, period: 800);
+        g.SetSrcRect(0x100, frameCount: 4, columns: 1, cell: 2, period: 800);
         var o = g.TryGet(0x100)!;
-        Assert.Equal(4, o.SrcGridW);
+        Assert.Equal(4, o.SrcFrameCount);
         Assert.Equal(2, o.SrcCell);
         Assert.Equal(800, o.SrcPeriod);
         Assert.True(o.SrcAnim);
@@ -91,10 +92,10 @@ public class AnimChannelTests
     public void SetSrcRect_ClampsGridToAtLeastOne()
     {
         var g = VisibleObj(0x100);
-        g.SetSrcRect(0x100, gridW: 0, gridH: 0, cell: 0, period: 0);
+        g.SetSrcRect(0x100, frameCount: 0, columns: 0, cell: 0, period: 0);
         var o = g.TryGet(0x100)!;
-        Assert.Equal(1, o.SrcGridW);
-        Assert.Equal(1, o.SrcGridH);
+        Assert.Equal(1, o.SrcFrameCount);
+        Assert.Equal(1, o.SrcColumns);
     }
 
     [Fact]

engine/Age.Engine.Tests/AnimInterpolatorTests.cs

@@ -8,7 +8,7 @@ public class AnimInterpolatorTests
     {
         var g = new GfxState();
         g.SetSurface(1, resId: 5, colorKey: -1);
-        g.BindDraw(handle, 1, 0, 0, 256, 64, 100, 100);   // 256x64 sheet, base pos (100,100)
+        g.BindDraw(handle, 1, 0, 0, 64, 64, 100, 100);   // one 64x64 cell, base pos (100,100)
         return g;
     }
 
@@ -24,22 +24,24 @@ public class AnimInterpolatorTests
     public void SrcRect_StaticCell_SelectsSubRect()
     {
         var g = VisibleObj(0x100);
-        g.SetSrcRect(0x100, gridW: 4, gridH: 1, cell: 2, period: 0);   // static cell 2 of 4 across 256px
+        g.SetSrcRect(0x100, frameCount: 4, columns: 4, cell: 2, period: 0);
         var ro = g.SnapshotVisibleObjects(0).Single();
         Assert.Equal(128, ro.SrcX);   // cell 2 * 64
         Assert.Equal(64, ro.W);
     }
 
     [Fact]
-    public void SrcRect_Animated_PingPongsCellAcrossGrid()
+    public void SrcRect_Animated_AdvancesOneCellPerPeriodAndWraps()
     {
         var g = VisibleObj(0x100);
-        g.SetSrcRect(0x100, gridW: 4, gridH: 1, cell: 0, period: 1000);
+        g.SetSrcRect(0x100, frameCount: 4, columns: 4, cell: 0, period: 100);
         g.SnapshotVisibleObjects(0);                       // seeds start=0
-        var half = g.SnapshotVisibleObjects(500).Single();
-        Assert.Equal(192, half.SrcX);                      // t=1 -> last cell (3) * 64
-        var back = g.SnapshotVisibleObjects(1000).Single();
-        Assert.Equal(0, back.SrcX);                        // ping-ponged back to cell 0
+        var second = g.SnapshotVisibleObjects(100).Single();
+        Assert.Equal(64, second.SrcX);
+        var fourth = g.SnapshotVisibleObjects(300).Single();
+        Assert.Equal(192, fourth.SrcX);
+        var wrapped = g.SnapshotVisibleObjects(400).Single();
+        Assert.Equal(0, wrapped.SrcX);
     }
 
     [Fact]

engine/Age.Engine.Tests/GfxAnimationTests.cs

@@ -82,6 +82,27 @@ public class GfxAnimationTests
         Assert.True(rotation.HasActiveVisualPresentation(1000));
     }
 
+    [Fact]
+    public void LoopingSpritesheet_PreservesCellSize_AdvancesRowMajor_AndWraps()
+    {
+        var g = new GfxState();
+        g.SetSurface(4, 0x37, -1);
+        g.BindDraw(0xcf3a, 4, 0, 0, 200, 200, 300, 100); // AE001H: 800x400, eight 200x200 cells
+        g.SetSrcRect(0xcf3a, frameCount: 8, columns: 4, cell: 0, period: 100);
+
+        var first = g.SnapshotVisibleObjects(1000).Single();
+        var second = g.SnapshotVisibleObjects(1100).Single();
+        var fifth = g.SnapshotVisibleObjects(1400).Single();
+        var eighth = g.SnapshotVisibleObjects(1700).Single();
+        var wrapped = g.SnapshotVisibleObjects(1800).Single();
+
+        Assert.Equal((0, 0, 200, 200), (first.SrcX, first.SrcY, first.W, first.H));
+        Assert.Equal((200, 0, 200, 200), (second.SrcX, second.SrcY, second.W, second.H));
+        Assert.Equal((0, 200, 200, 200), (fifth.SrcX, fifth.SrcY, fifth.W, fifth.H));
+        Assert.Equal((600, 200, 200, 200), (eighth.SrcX, eighth.SrcY, eighth.W, eighth.H));
+        Assert.Equal((0, 0, 200, 200), (wrapped.SrcX, wrapped.SrcY, wrapped.W, wrapped.H));
+    }
+
     [Fact]
     public void OneShotRotation_SharesMatrixClockAndMatchesNativeSample()
     {