protected override void PlatformCompressTexture(
ContentProcessorContext context, TextureContent content,
TextureProcessorOutputFormat format, bool isSpriteFont)
{
format = GetTextureFormatForPlatform(format, context.TargetPlatform);
// Make sure we're in a floating point format
content.ConvertBitmapType(typeof(PixelBitmapContent <RgbaVector>));
switch (format)
{
case TextureProcessorOutputFormat.AtcCompressed:
GraphicsUtil.CompressAti(content, isSpriteFont);
break;
case TextureProcessorOutputFormat.Color16Bit:
GraphicsUtil.CompressColor16Bit(content);
break;
case TextureProcessorOutputFormat.DxtCompressed:
GraphicsUtil.CompressDxt(context, content, isSpriteFont);
break;
case TextureProcessorOutputFormat.Etc1Compressed:
GraphicsUtil.CompressEtc1(context, content, isSpriteFont);
break;
case TextureProcessorOutputFormat.PvrCompressed:
GraphicsUtil.CompressPvrtc(context, content, isSpriteFont);
break;
}
}
public static void CompressDxt(ContentProcessorContext context, TextureContent content, bool isSpriteFont)
{
var face = content.Faces[0][0];
if (context.TargetProfile == GraphicsProfile.Reach)
{
if (!IsPowerOfTwo(face.Width) || !IsPowerOfTwo(face.Height))
{
throw new PipelineException(
"DXT compression requires width and height must " +
"be powers of two in Reach graphics profile.");
}
}
// Test the alpha channel to figure out if we have alpha.
var alphaRange = CalculateAlphaRange(face);
// TODO: This isn't quite right.
//
// We should be generating DXT1 textures for cutout alpha
// as DXT1 supports 1bit alpha and it uses less memory.
//
// XNA never generated DXT3 for textures... it always picked
// between DXT1 for cutouts and DXT5 for fractional alpha.
//
// DXT3 however can produce better results for high frequency
// alpha like a chain link fence where is DXT5 is better for
// low frequency alpha like clouds. I don't know how we can
// pick the right thing in this case without a hint.
if (isSpriteFont)
{
CompressFontDXT3(content);
}
else if (alphaRange == AlphaRange.Opaque)
{
content.ConvertBitmapType(typeof(Dxt1BitmapContent));
}
else if (alphaRange == AlphaRange.Cutout)
{
content.ConvertBitmapType(typeof(Dxt3BitmapContent));
}
else
{
content.ConvertBitmapType(typeof(Dxt5BitmapContent));
}
}
public static void CompressColor16Bit(TextureContent content)
{
var face = content.Faces[0][0];
var alphaRange = CalculateAlphaRange(face);
if (alphaRange == AlphaRange.Opaque)
{
content.ConvertBitmapType(typeof(PixelBitmapContent <Bgr565>));
}
else if (alphaRange == AlphaRange.Cutout)
{
content.ConvertBitmapType(typeof(PixelBitmapContent <Bgra5551>));
}
else
{
content.ConvertBitmapType(typeof(PixelBitmapContent <Bgra4444>));
}
}
/// <summary>
/// Performs conversion of the texture content to the correct format.
/// </summary>
/// <param name="context">The processor context.</param>
/// <param name="content">The content to be compressed.</param>
/// <param name="format">The user requested format for compression.</param>
/// <param name="isSpriteFont">If the texture has represents a sprite font, i.e. is greyscale and has sharp black/white contrast.</param>
public void ConvertTexture(
ContentProcessorContext context, TextureContent content, TextureProcessorOutputFormat format, bool isSpriteFont)
{
// We do nothing in this case.
if (format == TextureProcessorOutputFormat.NoChange)
{
return;
}
// If this is color just make sure the format is right and return it.
if (format == TextureProcessorOutputFormat.Color)
{
content.ConvertBitmapType(typeof(PixelBitmapContent <Color>));
return;
}
// Handle this common compression format.
if (format == TextureProcessorOutputFormat.Color16Bit)
{
GraphicsUtil.CompressColor16Bit(content);
return;
}
try
{
// All other formats require platform specific choices.
PlatformCompressTexture(context, content, format, isSpriteFont);
}
catch (EntryPointNotFoundException ex)
{
context.Logger.LogImportantMessage("Could not find the entry point to compress the texture. " + ex.ToString());
throw;
}
catch (DllNotFoundException ex)
{
context.Logger.LogImportantMessage("Could not compress texture. Required shared lib is missing. " + ex.ToString());
throw;
}
catch (Exception ex)
{
context.Logger.LogImportantMessage("Could not convert texture. " + ex.ToString());
throw;
}
}
public static void CompressAti(TextureContent content, bool isSpriteFont)
{
// If sharp alpha is required (for a font texture page), use 16-bit color instead of PVR
if (isSpriteFont)
{
CompressColor16Bit(content);
return;
}
var face = content.Faces[0][0];
var alphaRange = CalculateAlphaRange(face);
if (alphaRange == AlphaRange.Full)
{
content.ConvertBitmapType(typeof(AtcExplicitBitmapContent));
}
else
{
content.ConvertBitmapType(typeof(AtcInterpolatedBitmapContent));
}
}
public static void CompressEtc1(ContentProcessorContext context, TextureContent content, bool isSpriteFont)
{
// If sharp alpha is required (for a font texture page), use 16-bit color instead of PVR
if (isSpriteFont)
{
CompressColor16Bit(content);
return;
}
var face = content.Faces[0][0];
var alphaRange = CalculateAlphaRange(face);
// Use BGRA4444 for textures with non-opaque alpha values
if (alphaRange != AlphaRange.Opaque)
{
content.ConvertBitmapType(typeof(PixelBitmapContent <Bgra4444>));
}
else
{
// PVR SGX does not handle non-POT ETC1 textures.
// https://code.google.com/p/libgdx/issues/detail?id=1310
// Since we already enforce POT for PVR and DXT in Reach, we will also enforce POT for ETC1
if (!IsPowerOfTwo(face.Width) || !IsPowerOfTwo(face.Height))
{
context.Logger.LogWarning(
null, content.Identity,
"ETC1 compression requires width and height to be powers of two due to " +
"hardware restrictions on some devices. Falling back to BGR565.");
content.ConvertBitmapType(typeof(PixelBitmapContent <Bgr565>));
}
else
{
content.ConvertBitmapType(typeof(Etc1BitmapContent));
}
}
}
public static void CompressPvrtc(ContentProcessorContext context, TextureContent content, bool isSpriteFont)
{
// If sharp alpha is required (for a font texture page), use 16-bit color instead of PVR
if (isSpriteFont)
{
CompressColor16Bit(content);
return;
}
// Calculate number of mip levels
int width = content.Faces[0][0].Height;
int height = content.Faces[0][0].Width;
if (IsPowerOfTwo(width) && IsPowerOfTwo(height) && width == height)
{
var face = content.Faces[0][0];
var alphaRange = CalculateAlphaRange(face);
if (alphaRange == AlphaRange.Opaque)
{
content.ConvertBitmapType(typeof(PvrtcRgb4BitmapContent));
}
else
{
content.ConvertBitmapType(typeof(PvrtcRgba4BitmapContent));
}
}
else
{
context.Logger.LogWarning(
null, content.Identity,
"PVR compression requires width and height to " +
"be powers of two and equal. Falling back to 16-bit color.");
CompressColor16Bit(content);
}
}
protected abstract void PlatformCompressTexture(
ContentProcessorContext context, TextureContent content, TextureProcessorOutputFormat format, bool isSpriteFont);
// Compress the greyscale font texture page using a specially-formulated DXT3 mode
public static unsafe void CompressFontDXT3(TextureContent content)
{
if (content.Faces.Count > 1)
{
throw new PipelineException("Font textures should only have one face");
}
Span <Vector4> block = stackalloc Vector4[16];
for (int i = 0; i < content.Faces[0].Count; ++i)
{
var face = content.Faces[0][i];
var xBlocks = (face.Width + 3) / 4;
var yBlocks = (face.Height + 3) / 4;
var dxt3Size = xBlocks * yBlocks * 16;
byte[] buffer = new byte[dxt3Size];
var facePixels = face.GetPixelData();
fixed(byte *b = facePixels)
{
var colors = (Vector4 *)b;
int w;
int h = 0;
int x;
int y = 0;
while (h < (face.Height & ~3))
{
w = 0;
x = 0;
var h0 = h * face.Width;
var h1 = h0 + face.Width;
var h2 = h1 + face.Width;
var h3 = h2 + face.Width;
while (w < (face.Width & ~3))
{
block[0] = colors[w + h0];
block[1] = colors[w + h0 + 1];
block[2] = colors[w + h0 + 2];
block[3] = colors[w + h0 + 3];
block[4] = colors[w + h1];
block[5] = colors[w + h1 + 1];
block[6] = colors[w + h1 + 2];
block[7] = colors[w + h1 + 3];
block[8] = colors[w + h2];
block[9] = colors[w + h2 + 1];
block[10] = colors[w + h2 + 2];
block[11] = colors[w + h2 + 3];
block[12] = colors[w + h3];
block[13] = colors[w + h3 + 1];
block[14] = colors[w + h3 + 2];
block[15] = colors[w + h3 + 3];
int offset = (x + y * xBlocks) * 16;
CompressFontDXT3Block(block, buffer, offset);
w += 4;
++x;
}
// Do partial block at end of row
if (w < face.Width)
{
var cols = face.Width - w;
block.Clear();
for (int r = 0; r < 4; ++r)
{
h0 = (h + r) * face.Width;
for (int c = 0; c < cols; ++c)
{
block[(r * 4) + c] = colors[w + h0 + c];
}
}
int offset = (x + y * xBlocks) * 16;
CompressFontDXT3Block(block, buffer, offset);
}
h += 4;
y++;
}
// Do last partial row
if (h < face.Height)
{
var rows = face.Height - h;
w = 0;
x = 0;
while (w < (face.Width & ~3))
{
block.Clear();
for (int r = 0; r < rows; ++r)
{
var h0 = (h + r) * face.Width;
block[(r * 4) + 0] = colors[w + h0 + 0];
block[(r * 4) + 1] = colors[w + h0 + 1];
block[(r * 4) + 2] = colors[w + h0 + 2];
block[(r * 4) + 3] = colors[w + h0 + 3];
}
int offset = (x + y * xBlocks) * 16;
CompressFontDXT3Block(block, buffer, offset);
w += 4;
x++;
}
// Do last partial block
if (w < face.Width)
{
var cols = face.Width - w;
block.Clear();
for (int r = 0; r < rows; ++r)
{
var h0 = (h + r) * face.Width;
for (int c = 0; c < cols; ++c)
{
block[(r * 4) + c] = colors[w + h0 + c];
}
}
int offset = (x + y * xBlocks) * 16;
CompressFontDXT3Block(block, buffer, offset);
}
}
}
var dxt3 = new Dxt3BitmapContent(face.Width, face.Height);
dxt3.SetPixelData(buffer);
content.Faces[0][i] = dxt3;
}
}