diff --git a/src/AcDream.App/Rendering/TerrainAtlas.cs b/src/AcDream.App/Rendering/TerrainAtlas.cs
index 6e8584a..faa3a6e 100644
--- a/src/AcDream.App/Rendering/TerrainAtlas.cs
+++ b/src/AcDream.App/Rendering/TerrainAtlas.cs
@@ -316,10 +316,10 @@ public sealed unsafe class TerrainAtlas : IDisposable
return false;
// Alpha maps ship as PFID_CUSTOM_LSCAPE_ALPHA (AC's landscape-alpha
- // format) or the more generic PFID_A8; SurfaceDecoder routes both
- // through the same "replicate single byte to RGBA" path. Palette is
- // not used.
- var d = SurfaceDecoder.DecodeRenderSurface(rs, palette: null);
+ // format) or the more generic PFID_A8; terrain blending alpha masks
+ // MUST use isAdditive=true so R=G=B=A=val — the terrain fragment shader
+ // reads .r for the blend weight. Palette is not used.
+ var d = SurfaceDecoder.DecodeRenderSurface(rs, palette: null, isClipMap: false, isAdditive: true);
if (ReferenceEquals(d, DecodedTexture.Magenta))
return false;
diff --git a/src/AcDream.App/Rendering/TextureCache.cs b/src/AcDream.App/Rendering/TextureCache.cs
index 077a12c..b5585c3 100644
--- a/src/AcDream.App/Rendering/TextureCache.cs
+++ b/src/AcDream.App/Rendering/TextureCache.cs
@@ -199,8 +199,9 @@ public sealed unsafe class TextureCache : IDisposable
// Clipmap surfaces use palette indices 0..7 as transparent sentinels.
bool isClipMap = surface.Type.HasFlag(SurfaceType.Base1ClipMap);
+ bool isAdditive = surface.Type.HasFlag(SurfaceType.Additive);
- return SurfaceDecoder.DecodeRenderSurface(rs, effectivePalette, isClipMap);
+ return SurfaceDecoder.DecodeRenderSurface(rs, effectivePalette, isClipMap, isAdditive);
}
///
diff --git a/src/AcDream.Core/Textures/SurfaceDecoder.cs b/src/AcDream.Core/Textures/SurfaceDecoder.cs
index e48b9a4..8b3158f 100644
--- a/src/AcDream.Core/Textures/SurfaceDecoder.cs
+++ b/src/AcDream.Core/Textures/SurfaceDecoder.cs
@@ -1,5 +1,6 @@
using BCnEncoder.Decoder;
using BCnEncoder.Shared;
+using Chorizite.OpenGLSDLBackend.Lib;
using DatReaderWriter.DBObjs;
using DatReaderWriter.Enums;
@@ -16,7 +17,7 @@ public static class SurfaceDecoder
/// when a palette is available.
///
public static DecodedTexture DecodeRenderSurface(RenderSurface rs)
- => DecodeRenderSurface(rs, palette: null);
+ => DecodeRenderSurface(rs, palette: null, isClipMap: false, isAdditive: false);
///
/// Decode a RenderSurface's pixel bytes into RGBA8 with optional palette support.
@@ -24,8 +25,11 @@ public static class SurfaceDecoder
/// 16-bit value in SourceData is treated as an index into .
/// When is true on an indexed surface, palette indices
/// below 8 are forced to fully-transparent (AC's clipmap alpha-key convention).
+ /// When is true, A8/CUSTOM_LSCAPE_ALPHA surfaces
+ /// replicate the byte into all four channels (R=G=B=A=val, for terrain alpha masks
+ /// and additive surfaces). When false, R=G=B=255, A=val (WB FillA8 semantics).
///
- public static DecodedTexture DecodeRenderSurface(RenderSurface rs, Palette? palette, bool isClipMap = false)
+ public static DecodedTexture DecodeRenderSurface(RenderSurface rs, Palette? palette, bool isClipMap = false, bool isAdditive = false)
{
if (rs.SourceData is null || rs.Width <= 0 || rs.Height <= 0)
return DecodedTexture.Magenta;
@@ -40,9 +44,11 @@ public static class SurfaceDecoder
PixelFormat.PFID_DXT1 => DecodeBc(rs, CompressionFormat.Bc1, isClipMap),
PixelFormat.PFID_DXT3 => DecodeBc(rs, CompressionFormat.Bc2, isClipMap),
PixelFormat.PFID_DXT5 => DecodeBc(rs, CompressionFormat.Bc3, isClipMap),
- PixelFormat.PFID_A8 or PixelFormat.PFID_CUSTOM_LSCAPE_ALPHA => DecodeA8(rs),
+ PixelFormat.PFID_A8 or PixelFormat.PFID_CUSTOM_LSCAPE_ALPHA => DecodeA8(rs, isAdditive),
PixelFormat.PFID_P8 when palette is not null => DecodeP8(rs, palette, isClipMap),
PixelFormat.PFID_INDEX16 when palette is not null => DecodeIndex16(rs, palette, isClipMap),
+ PixelFormat.PFID_R5G6B5 => DecodeR5G6B5(rs),
+ PixelFormat.PFID_A4R4G4B4 => DecodeA4R4G4B4(rs),
_ => DecodedTexture.Magenta,
};
}
@@ -59,33 +65,7 @@ public static class SurfaceDecoder
return DecodedTexture.Magenta;
var rgba = new byte[rs.Width * rs.Height * 4];
- int paletteMax = palette.Colors.Count - 1;
- for (int i = 0; i < rs.Width * rs.Height; i++)
- {
- // Read each 16-bit value little-endian as a palette index
- int src = i * 2;
- ushort idx = (ushort)(rs.SourceData[src] | (rs.SourceData[src + 1] << 8));
- if (idx > paletteMax) idx = 0;
- var c = palette.Colors[idx];
-
- int dst = i * 4;
- // Clipmap alpha-key convention (ACViewer: if (isClipMap && color < 8) r=g=b=a=0):
- // palette indices 0..7 on clipmap surfaces represent transparent pixels.
- if (isClipMap && idx < 8)
- {
- rgba[dst + 0] = 0;
- rgba[dst + 1] = 0;
- rgba[dst + 2] = 0;
- rgba[dst + 3] = 0;
- }
- else
- {
- rgba[dst + 0] = c.Red;
- rgba[dst + 1] = c.Green;
- rgba[dst + 2] = c.Blue;
- rgba[dst + 3] = c.Alpha;
- }
- }
+ TextureHelpers.FillIndex16(rs.SourceData, palette, rgba.AsSpan(), rs.Width, rs.Height, isClipMap);
return new DecodedTexture(rgba, rs.Width, rs.Height);
}
@@ -109,30 +89,22 @@ public static class SurfaceDecoder
}
///
- /// Decode single-byte-per-pixel alpha (PFID_A8 / PFID_CUSTOM_LSCAPE_ALPHA)
- /// into RGBA8 by replicating each alpha byte into all four channels. AC's
- /// terrain blending alpha masks are stored as PFID_CUSTOM_LSCAPE_ALPHA and
- /// other generic 8-bit alpha surfaces use PFID_A8; the bit layout is
- /// identical so one decoder handles both. Replicating into all four
- /// channels lets the fragment shader pull "the blend amount" from either
- /// .a or .r without special-casing.
+ /// Decode single-byte-per-pixel alpha (PFID_A8 / PFID_CUSTOM_LSCAPE_ALPHA) into RGBA8.
+ /// When is true: R=G=B=A=val (terrain alpha masks and
+ /// additive entity textures — the shader reads .r for the blend weight). When false:
+ /// R=G=B=255, A=val (WB FillA8 semantics for non-additive entity textures).
///
- private static DecodedTexture DecodeA8(RenderSurface rs)
+ private static DecodedTexture DecodeA8(RenderSurface rs, bool isAdditive)
{
int expected = rs.Width * rs.Height;
if (rs.SourceData.Length < expected)
return DecodedTexture.Magenta;
var rgba = new byte[expected * 4];
- for (int i = 0; i < expected; i++)
- {
- byte a = rs.SourceData[i];
- int d = i * 4;
- rgba[d + 0] = a;
- rgba[d + 1] = a;
- rgba[d + 2] = a;
- rgba[d + 3] = a;
- }
+ if (isAdditive)
+ TextureHelpers.FillA8Additive(rs.SourceData, rgba.AsSpan(), rs.Width, rs.Height);
+ else
+ TextureHelpers.FillA8(rs.SourceData, rgba.AsSpan(), rs.Width, rs.Height);
return new DecodedTexture(rgba, rs.Width, rs.Height);
}
@@ -143,15 +115,7 @@ public static class SurfaceDecoder
return DecodedTexture.Magenta;
var rgba = new byte[expected];
- // Source layout per pixel: B, G, R, A → swap to R, G, B, A
- for (int i = 0; i < rs.Width * rs.Height; i++)
- {
- int s = i * 4;
- rgba[s + 0] = rs.SourceData[s + 2]; // R <- R
- rgba[s + 1] = rs.SourceData[s + 1]; // G <- G
- rgba[s + 2] = rs.SourceData[s + 0]; // B <- B
- rgba[s + 3] = rs.SourceData[s + 3]; // A <- A
- }
+ TextureHelpers.FillA8R8G8B8(rs.SourceData, rgba.AsSpan(), rs.Width, rs.Height);
return new DecodedTexture(rgba, rs.Width, rs.Height);
}
@@ -168,29 +132,7 @@ public static class SurfaceDecoder
return DecodedTexture.Magenta;
var rgba = new byte[rs.Width * rs.Height * 4];
- int paletteMax = palette.Colors.Count - 1;
- for (int i = 0; i < rs.Width * rs.Height; i++)
- {
- int idx = rs.SourceData[i];
- if (idx > paletteMax) idx = 0;
- var c = palette.Colors[idx];
-
- int dst = i * 4;
- if (isClipMap && idx < 8)
- {
- rgba[dst + 0] = 0;
- rgba[dst + 1] = 0;
- rgba[dst + 2] = 0;
- rgba[dst + 3] = 0;
- }
- else
- {
- rgba[dst + 0] = c.Red;
- rgba[dst + 1] = c.Green;
- rgba[dst + 2] = c.Blue;
- rgba[dst + 3] = c.Alpha;
- }
- }
+ TextureHelpers.FillP8(rs.SourceData, palette, rgba.AsSpan(), rs.Width, rs.Height, isClipMap);
return new DecodedTexture(rgba, rs.Width, rs.Height);
}
@@ -207,16 +149,7 @@ public static class SurfaceDecoder
return DecodedTexture.Magenta;
var rgba = new byte[rs.Width * rs.Height * 4];
- for (int i = 0; i < rs.Width * rs.Height; i++)
- {
- int src = i * 3;
- int dst = i * 4;
- // On-disk byte order: B, G, R (little-endian 24-bit BGR, same as DX PFID_R8G8B8)
- rgba[dst + 0] = rs.SourceData[src + 2]; // R
- rgba[dst + 1] = rs.SourceData[src + 1]; // G
- rgba[dst + 2] = rs.SourceData[src + 0]; // B
- rgba[dst + 3] = 0xFF; // A = opaque
- }
+ TextureHelpers.FillR8G8B8(rs.SourceData, rgba.AsSpan(), rs.Width, rs.Height);
return new DecodedTexture(rgba, rs.Width, rs.Height);
}
@@ -245,6 +178,28 @@ public static class SurfaceDecoder
return new DecodedTexture(rgba, rs.Width, rs.Height);
}
+ private static DecodedTexture DecodeR5G6B5(RenderSurface rs)
+ {
+ int expectedBytes = rs.Width * rs.Height * 2;
+ if (rs.SourceData.Length < expectedBytes)
+ return DecodedTexture.Magenta;
+
+ var rgba = new byte[rs.Width * rs.Height * 4];
+ TextureHelpers.FillR5G6B5(rs.SourceData, rgba.AsSpan(), rs.Width, rs.Height);
+ return new DecodedTexture(rgba, rs.Width, rs.Height);
+ }
+
+ private static DecodedTexture DecodeA4R4G4B4(RenderSurface rs)
+ {
+ int expectedBytes = rs.Width * rs.Height * 2;
+ if (rs.SourceData.Length < expectedBytes)
+ return DecodedTexture.Magenta;
+
+ var rgba = new byte[rs.Width * rs.Height * 4];
+ TextureHelpers.FillA4R4G4B4(rs.SourceData, rgba.AsSpan(), rs.Width, rs.Height);
+ return new DecodedTexture(rgba, rs.Width, rs.Height);
+ }
+
private static DecodedTexture DecodeBc(RenderSurface rs, CompressionFormat format, bool isClipMap)
{
var pixels = BcDecoder.DecodeRaw(rs.SourceData, rs.Width, rs.Height, format);