Implement a software ETC2 texture decoder (#4121)

* Implement a software ETC2 texture decoder

* Fix output size calculation for non-2D textures

* Address PR feedback

3 files changed, 48 insertions, 10 deletions

diff --git a/Ryujinx.Graphics.Gpu/Image/FormatTable.cs b/Ryujinx.Graphics.Gpu/Image/FormatTable.cs
index c76e1fca..72901610 100644
--- a/Ryujinx.Graphics.Gpu/Image/FormatTable.cs
+++ b/Ryujinx.Graphics.Gpu/Image/FormatTable.cs
@@ -208,8 +208,10 @@ namespace Ryujinx.Graphics.Gpu.Image
             Bc6HSf16Float                    = Bc6HSf16          | RFloat | GFloat | BFloat | AFloat,        // 0x7ff90
             Bc6HUf16Float                    = Bc6HUf16          | RFloat | GFloat | BFloat | AFloat,        // 0x7ff91
             Etc2RgbUnorm                     = Etc2Rgb           | RUnorm | GUnorm | BUnorm | AUnorm,        // 0x24906
+            Etc2RgbPtaUnorm                  = Etc2RgbPta        | RUnorm | GUnorm | BUnorm | AUnorm,        // 0x2490a
             Etc2RgbaUnorm                    = Etc2Rgba          | RUnorm | GUnorm | BUnorm | AUnorm,        // 0x2490b
             Etc2RgbUnormSrgb                 = Etc2Rgb           | RUnorm | GUnorm | BUnorm | AUnorm | Srgb, // 0xa4906
+            Etc2RgbPtaUnormSrgb              = Etc2RgbPta        | RUnorm | GUnorm | BUnorm | AUnorm | Srgb, // 0xa490a
             Etc2RgbaUnormSrgb                = Etc2Rgba          | RUnorm | GUnorm | BUnorm | AUnorm | Srgb, // 0xa490b
             Astc2D4x4Unorm                   = Astc2D4x4         | RUnorm | GUnorm | BUnorm | AUnorm,        // 0x24940
             Astc2D5x4Unorm                   = Astc2D5x4         | RUnorm | GUnorm | BUnorm | AUnorm,        // 0x24950
@@ -429,8 +431,10 @@ namespace Ryujinx.Graphics.Gpu.Image
             { TextureFormat.Bc6HSf16Float,                    new FormatInfo(Format.Bc6HSfloat,        4,  4,  16, 4) },
             { TextureFormat.Bc6HUf16Float,                    new FormatInfo(Format.Bc6HUfloat,        4,  4,  16, 4) },
             { TextureFormat.Etc2RgbUnorm,                     new FormatInfo(Format.Etc2RgbUnorm,      4,  4,  8,  3) },
+            { TextureFormat.Etc2RgbPtaUnorm,                  new FormatInfo(Format.Etc2RgbPtaUnorm,   4,  4,  8,  4) },
             { TextureFormat.Etc2RgbaUnorm,                    new FormatInfo(Format.Etc2RgbaUnorm,     4,  4,  16, 4) },
             { TextureFormat.Etc2RgbUnormSrgb,                 new FormatInfo(Format.Etc2RgbSrgb,       4,  4,  8,  3) },
+            { TextureFormat.Etc2RgbPtaUnormSrgb,              new FormatInfo(Format.Etc2RgbPtaSrgb,    4,  4,  8,  4) },
             { TextureFormat.Etc2RgbaUnormSrgb,                new FormatInfo(Format.Etc2RgbaSrgb,      4,  4,  16, 4) },
             { TextureFormat.Astc2D4x4Unorm,                   new FormatInfo(Format.Astc4x4Unorm,      4,  4,  16, 4) },
             { TextureFormat.Astc2D5x4Unorm,                   new FormatInfo(Format.Astc5x4Unorm,      5,  4,  16, 4) },
diff --git a/Ryujinx.Graphics.Gpu/Image/Texture.cs b/Ryujinx.Graphics.Gpu/Image/Texture.cs
index 4203cb00..904c908f 100644
--- a/Ryujinx.Graphics.Gpu/Image/Texture.cs
+++ b/Ryujinx.Graphics.Gpu/Image/Texture.cs
@@ -857,9 +857,23 @@ namespace Ryujinx.Graphics.Gpu.Image
 
                 result = decoded;
             }
-            else if (!_context.Capabilities.SupportsR4G4Format && Format == Format.R4G4Unorm)
+            else if (!_context.Capabilities.SupportsEtc2Compression && Format.IsEtc2())
             {
-                result = PixelConverter.ConvertR4G4ToR4G4B4A4(result);
+                switch (Format)
+                {
+                    case Format.Etc2RgbaSrgb:
+                    case Format.Etc2RgbaUnorm:
+                        result = ETC2Decoder.DecodeRgba(result, width, height, depth, levels, layers);
+                        break;
+                    case Format.Etc2RgbPtaSrgb:
+                    case Format.Etc2RgbPtaUnorm:
+                        result = ETC2Decoder.DecodePta(result, width, height, depth, levels, layers);
+                        break;
+                    case Format.Etc2RgbSrgb:
+                    case Format.Etc2RgbUnorm:
+                        result = ETC2Decoder.DecodeRgb(result, width, height, depth, levels, layers);
+                        break;
+                }
             }
             else if (!TextureCompatibility.HostSupportsBcFormat(Format, Target, _context.Capabilities))
             {
@@ -895,6 +909,10 @@ namespace Ryujinx.Graphics.Gpu.Image
                         break;
                 }
             }
+            else if (!_context.Capabilities.SupportsR4G4Format && Format == Format.R4G4Unorm)
+            {
+                result = PixelConverter.ConvertR4G4ToR4G4B4A4(result);
+            }
 
             return result;
         }
diff --git a/Ryujinx.Graphics.Gpu/Image/TextureCompatibility.cs b/Ryujinx.Graphics.Gpu/Image/TextureCompatibility.cs
index 91a1a728..642e03b6 100644
--- a/Ryujinx.Graphics.Gpu/Image/TextureCompatibility.cs
+++ b/Ryujinx.Graphics.Gpu/Image/TextureCompatibility.cs
@@ -67,6 +67,10 @@ namespace Ryujinx.Graphics.Gpu.Image
         /// <returns>A host compatible format</returns>
         public static FormatInfo ToHostCompatibleFormat(TextureInfo info, Capabilities caps)
         {
+            // The host API does not support those compressed formats.
+            // We assume software decompression will be done for those textures,
+            // and so we adjust the format here to match the decompressor output.
+
             if (!caps.SupportsAstcCompression)
             {
                 if (info.FormatInfo.Format.IsAstcUnorm())
@@ -83,16 +87,8 @@ namespace Ryujinx.Graphics.Gpu.Image
                 }
             }
 
-            if (!caps.SupportsR4G4Format && info.FormatInfo.Format == Format.R4G4Unorm)
-            {
-                return new FormatInfo(Format.R4G4B4A4Unorm, 1, 1, 2, 4);
-            }
-
             if (!HostSupportsBcFormat(info.FormatInfo.Format, info.Target, caps))
             {
-                // The host API does not this compressed format.
-                // We assume software decompression will be done for those textures,
-                // and so we adjust the format here to match the decompressor output.
                 switch (info.FormatInfo.Format)
                 {
                     case Format.Bc1RgbaSrgb:
@@ -119,6 +115,26 @@ namespace Ryujinx.Graphics.Gpu.Image
                 }
             }
 
+            if (!caps.SupportsEtc2Compression)
+            {
+                switch (info.FormatInfo.Format)
+                {
+                    case Format.Etc2RgbaSrgb:
+                    case Format.Etc2RgbPtaSrgb:
+                    case Format.Etc2RgbSrgb:
+                        return new FormatInfo(Format.R8G8B8A8Srgb, 1, 1, 4, 4);
+                    case Format.Etc2RgbaUnorm:
+                    case Format.Etc2RgbPtaUnorm:
+                    case Format.Etc2RgbUnorm:
+                        return new FormatInfo(Format.R8G8B8A8Unorm, 1, 1, 4, 4);
+                }
+            }
+
+            if (!caps.SupportsR4G4Format && info.FormatInfo.Format == Format.R4G4Unorm)
+            {
+                return new FormatInfo(Format.R4G4B4A4Unorm, 1, 1, 2, 4);
+            }
+
             return info.FormatInfo;
         }