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>));
}
}
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);
}
}
/// <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;
}
}
