internal Surface(DirectDrawSurface7 _handle)
{
this.surface = _handle;
// compute the size of this surface
DDSURFACEDESC2 desc = new DDSURFACEDESC2();
surface.GetSurfaceDesc(ref desc);
this.size = new Size(desc.lWidth, desc.lHeight);
resetClipRect();
// compute the bit shift width for color fill
DDPIXELFORMAT pixelFormat = new DDPIXELFORMAT();
surface.GetPixelFormat(ref pixelFormat);
widthR = countBitWidth(pixelFormat.lRBitMask);
widthG = countBitWidth(pixelFormat.lGBitMask);
widthB = countBitWidth(pixelFormat.lBBitMask);
}
private void CalculateImageSettings(
ref DDSURFACEDESC2 ddsd,
out int compressionFactor,
out int glPixelFormat,
out int elementsPerPixel,
out PixelFormatConverter converter)
{
converter = DoNothingConverter;
DDPIXELFORMAT pixelFormat = ddsd.ddpfPixelFormat;
if ((pixelFormat.dwFlags & DDPIXELFORMAT.DDPF_RGB) != 0)
{
// Uncompressed DXT
switch (pixelFormat.dwRGBBitCount)
{
case 32:
elementsPerPixel = 4;
if (pixelFormat.HasAlphaRedGreenBlueMasks(
0xFF000000,
0x00FF0000,
0x0000FF00,
0x000000FF))
{
glPixelFormat = Gl.GL_BGRA; //OpenGl's format tag is the reverse order
}
else if (pixelFormat.HasAlphaRedGreenBlueMasks(
0xFF000000,
0x000000FF,
0x0000FF00,
0x00FF0000))
{
glPixelFormat = Gl.GL_RGBA;
}
else if (pixelFormat.HasRedGreenBlueMasks(
0x00FF0000,
0x0000FF00,
0x000000FF))
{
glPixelFormat = Gl.GL_BGR;
converter = Create32BitTo24BitConverter(0, 1, 2);
elementsPerPixel = 3;
}
else if (pixelFormat.HasRedGreenBlueMasks(
0x000000FF,
0x0000FF00,
0x00FF0000))
{
glPixelFormat = Gl.GL_RGB;
converter = Create32BitTo24BitConverter(0, 1, 2);
elementsPerPixel = 3;
}
else
{
glPixelFormat = Gl.GL_RGBA;
}
break;
case 24:
elementsPerPixel = 3;
if (pixelFormat.HasRedGreenBlueMasks(
0x00FF0000,
0x0000FF00,
0x000000FF))
{
glPixelFormat = Gl.GL_BGR;
}
else
{
glPixelFormat = Gl.GL_RGB;
}
break;
default:
throw new NotSupportedException("unhandled pixel format in dds file");
}
compressionFactor = 0;
return;
}
// compressed?
switch (pixelFormat.dwFourCC)
{
case DDPIXELFORMAT.FOURCC_DXT1:
// DXT1's compression ratio is 8:1
compressionFactor = 2;
glPixelFormat = Gl.GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
elementsPerPixel = 3;
break;
case DDPIXELFORMAT.FOURCC_DXT3:
// DXT3's compression ratio is 4:1
compressionFactor = 4;
glPixelFormat = Gl.GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
elementsPerPixel = 4;
break;
case DDPIXELFORMAT.FOURCC_DXT5:
// DXT5's compression ratio is 4:1
compressionFactor = 4;
glPixelFormat = Gl.GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
elementsPerPixel = 4;
break;
default:
throw new NotSupportedException("Unsupported DXT format");
}
}
