/// <summary>
/// Builds a 3d noise texture
/// </summary>
/// <param name="parameters">Builder parameters</param>
/// <returns>Returns a <see cref="Texture3dData"/> object containing the generated noise texture</returns>
/// <exception cref="System.ArgumentNullException">Thrown if parameters is null</exception>
/// <exception cref="System.IO.InvalidDataException">Thrown if parameters are invalid</exception>
public static unsafe Texture3dData Build( Noise3dTextureBuilderParameters parameters )
{
Arguments.CheckNotNull( parameters, "parameters" );
parameters.Validate( );
Texture3dData data = new Texture3dData( parameters.Width, parameters.Height, parameters.Depth, parameters.Format );
fixed( byte* voxels = data.Bytes )
{
GenerateNoise( data, parameters, voxels );
}
return data;
}
/// <summary>
/// Writes a 3d texture to a stream
/// </summary>
/// <param name="textureDataArray">Texture data array</param>
/// <param name="stream">Stream to write to</param>
public static void WriteTextureToStream( Texture3dData[] textureDataArray, Stream stream )
{
Arguments.CheckNotNullAndContainsNoNulls( textureDataArray, "textureDataArray" );
Arguments.CheckNotNull( stream, "stream" );
if ( textureDataArray.Length == 0 )
{
throw new ArgumentException( "Texture data array was empty - must contain at least one element", "textureDataArray" );
}
using ( BinaryWriter writer = new BinaryWriter( stream ) )
{
writer.Write( TextureFileFormatVersion1.TextureFileIdentifier );
TextureFileFormatVersion1.Group headerGroup = new TextureFileFormatVersion1.Group( );
headerGroup.GroupId = GroupIdentifier.TextureHeaderGroup;
long startOfHeaderGroup = BeginGroup( writer, headerGroup );
// Write the header
TextureFileFormatVersion1.Header header = new TextureFileFormatVersion1.Header( );
header.Dimensions = 3;
header.Format = textureDataArray[ 0 ].Format;
header.TextureDataEntries = textureDataArray.Length;
header.Write( writer );
// Write texture data
TextureFileFormatVersion1.Group textureDataGroup = new TextureFileFormatVersion1.Group( );
textureDataGroup.GroupId = GroupIdentifier.Texture3dDataGroup;
for ( int textureDataIndex = 0; textureDataIndex < textureDataArray.Length; ++textureDataIndex )
{
// Write the texture group
long startOfTextureGroup = BeginGroup( writer, textureDataGroup );
Texture3dData textureData = textureDataArray[ textureDataIndex ];
// Write texture data
writer.Write( textureData.Width );
writer.Write( textureData.Height );
writer.Write( textureData.Depth );
writer.Write( textureData.Bytes );
// Update the texture group
EndGroup( writer, startOfTextureGroup );
}
// Update group with correct size
EndGroup( writer, startOfHeaderGroup );
}
}
/// <summary>
/// Loads 3d texture data from the specified stream
/// </summary>
private static Texture3dData[] Load3dTextureData( BinaryReader reader, TextureFileFormatVersion1.Header header )
{
Texture3dData[] textureDataArray = new Texture3dData[ header.TextureDataEntries ];
for ( int textureDataCount = 0; textureDataCount < header.TextureDataEntries; ++textureDataCount )
{
TextureFileFormatVersion1.Group textureGroup = TextureFileFormatVersion1.Group.Read( reader );
if ( textureGroup.GroupId != GroupIdentifier.Texture3dDataGroup )
{
throw new FileLoadException( "Expected texture group" );
}
int width = reader.ReadInt32( );
int height = reader.ReadInt32( );
int depth = reader.ReadInt32( );
Texture3dData texData = new Texture3dData( );
texData.Create( width, height, depth, header.Format );
reader.Read( texData.Bytes, 0, texData.Bytes.Length );
textureDataArray[ textureDataCount ] = texData;
}
return textureDataArray;
}
//
// Discrepancies in atmospheric modelling papers:
// - HG:
// - Neilsen: HG(t,g) = (1-g2)/(4pi(1 + g2 - 2cos(t))^1.5)
// - Wolfram: HG(t,g) = (1-g2)/(1 + g2 - 2.g.cos(t))^1.5
// - O'Neil (adapted HG): HG(t,g) = 3(1-g2)/2(2+g2) . (1+t2)/(1+g2 - 2gt)^1.5
// - O'Neil and Wolfram work well. Neilsen doesn't (denominator can evalute to < 0 before raising to 3/2 power)
// - Scattering coefficients: (# is wavelength)
// - Neilsen Rayleigh coefficient: 8pi^2(n2-1)^2/3N#^4
// - Neilsen Mie coefficient: 0.434c.pi.4pi^2/#^2K
// - K=non-wavelength dependent fudge factor for Bm: ~0.67
// - c=concentration factor(0.6544T-0.6510).10e-16 (T=turbidity. ~555nm)
//
//
//
//
// Realtime rendering of atmospheric scattering for flight simulators:
// http://www2.imm.dtu.dk/pubdb/views/edoc_download.php/2554/pdf/imm2554.pdf
//
// Display of The Earth Taking into Account Atmospheric Scattering: (Nishita)
// http://nis-lab.is.s.u-tokyo.ac.jp/~nis/abs_sig.html#sig93
//
// Implementation of Nishita's paper:
// http://www.gamedev.net/reference/articles/article2093.asp
//
// A practical analytical model of daylight:
// http://www.cs.utah.edu/vissim/papers/sunsky/sunsky.pdf
//
// Discussion about atmospheric shaders:
// http://www.gamedev.net/community/forums/topic.asp?topic_id=335023
//
// Paper that this model is based on:
// http://www.vis.uni-stuttgart.de/~schafhts/HomePage/pubs/wscg07-schafhitzel.pdf
//
// Heyney-Greenstein on Mathworld:
// http://scienceworld.wolfram.com/physics/Heyney-GreensteinPhaseFunction.html
//
/// <summary>
/// Builds a 3D lookup texture
/// </summary>
/// <param name="model">The atmosphere model</param>
/// <param name="parameters">Parameters for the build process</param>
/// <param name="progress">Optional progress object</param>
/// <returns>Returns a 3d texture data. Returns null if cancel was flagged in the progress object</returns>
public unsafe AtmosphereBuildOutputs Build( AtmosphereBuildModel model, AtmosphereBuildParameters parameters, AtmosphereBuildProgress progress )
{
Texture2dData opticalDepthTexture = new Texture2dData( );
Texture3dData scatteringTexture = new Texture3dData( );
scatteringTexture.Create( parameters.ViewAngleSamples, parameters.SunAngleSamples, parameters.HeightSamples, TextureFormat.R8G8B8A8 );
SetupModelAndParameters( parameters, model );
progress = progress ?? new AtmosphereBuildProgress( );
fixed ( byte* voxels = scatteringTexture.Bytes )
{
if ( !BuildScatteringTexture( parameters, voxels, progress ) )
{
return null;
}
}
if ( progress.Cancel )
{
return null;
}
opticalDepthTexture.Create( parameters.OpticalDepthResolution, parameters.OpticalDepthResolution, TextureFormat.R8G8B8 );
fixed ( byte* pixels = opticalDepthTexture.Bytes )
{
if ( !BuildOpticalDepthTexture( parameters, pixels, progress ) )
{
return null;
}
}
return new AtmosphereBuildOutputs( scatteringTexture, opticalDepthTexture );
}
/// <summary>
/// Generates a toroidally tiled noise
/// </summary>
private static unsafe void GenerateNoise( Texture3dData data, Noise3dTextureBuilderParameters parameters, byte* voxels )
{
SimpleNoise3d sNoise = new SimpleNoise3d();
Noise noise = new Noise( );
float nW = parameters.NoiseWidth;
float nH = parameters.NoiseHeight;
float nD = parameters.NoiseDepth;
float nX0 = parameters.NoiseX;
float nY0 = parameters.NoiseY;
float nZ0 = parameters.NoiseZ;
float nXInc = nW / data.Width;
float nYInc = nH / data.Height;
float nZInc = nD / data.Depth;
byte* voxel = voxels;
int bytesPerVoxel = TextureFormatInfo.GetSizeInBytes( parameters.Format );
if ( bytesPerVoxel != 3 && bytesPerVoxel != 4 )
{
throw new InvalidDataException( string.Format( "Unexpected voxel stride of {0} - expected either 3 or 4 from format {1}", bytesPerVoxel, parameters.Format ) );
}
// Check hacked channel expectations...
bool hasAlpha = TextureFormatInfo.HasAlphaChannel( parameters.Format );
float nZ = nZ0;
float maxNoise = float.MinValue;
float minNoise = float.MaxValue;
for ( int z = 0; z < parameters.Depth; ++z, nZ += nZInc )
{
float nY = nY0;
for ( int y = 0; y < parameters.Height; ++y, nY += nYInc )
{
float nX = nX0;
for ( int x = 0; x < parameters.Width; ++x, nX += nXInc )
{
switch ( parameters.GenerationType )
{
case NoiseGenerationType.Grayscale :
{
float n = ( 1.0f + sNoise.GetTilingNoise( nX, nY, nZ, nW, nH, nD ) ) / 2;
maxNoise = Math.Max( maxNoise, n );
minNoise = Math.Min( minNoise, n );
// float n = 0.5f + noise.GetNoise( nX, nY, nZ );
voxel[ 0 ] = NoiseToByte( n );
voxel[ 1 ] = voxel[ 0 ];
voxel[ 2 ] = voxel[ 0 ];
if ( hasAlpha )
{
voxel[ 3 ] = voxel[ 0 ];
}
break;
}
case NoiseGenerationType.MultiChannel :
{
float r = noise.GetNoise( nX, nY, nZ );
float g = noise.GetNoise( nX + nW, nY, nZ );
float b = noise.GetNoise( nX, nY + nH, nZ );
voxel[ 0 ] = NoiseToByte( r );
voxel[ 1 ] = NoiseToByte( g );
voxel[ 2 ] = NoiseToByte( b );
if ( hasAlpha )
{
float a = noise.GetNoise( nX, nY, nZ + parameters.NoiseDepth );
voxel[ 3 ] = NoiseToByte( a );
}
break;
}
case NoiseGenerationType.TilingGrayscale :
{
float n = GetTiledNoise( noise, nX, nY, nZ, nX0, nY0, nZ0, nW, nH, nD );
voxel[ 0 ] = NoiseToByte( n );
voxel[ 1 ] = voxel[ 0 ];
voxel[ 2 ] = voxel[ 0 ];
if ( hasAlpha )
{
voxel[ 3 ] = voxel[ 0 ];
}
break;
}
case NoiseGenerationType.TilingMultiChannel :
{
float r = GetTiledNoise( noise, nX, nY, nZ, nX0, nY0, nZ0, nW, nH, nD );
float g = GetTiledNoise( noise, nX + nW, nY, nZ, nX0 + nW, nY0, nZ0, nW, nH, nD );
float b = GetTiledNoise( noise, nX, nY + nH, nZ, nX0, nY0 + nH, nZ0, nW, nH, nD );
voxel[ 0 ] = NoiseToByte( r );
voxel[ 1 ] = NoiseToByte( g );
voxel[ 2 ] = NoiseToByte( b );
if ( hasAlpha )
{
float a = GetTiledNoise( noise, nX, nY, nZ + nD, nX0, nY0, nZ0 + nD, nW, nH, nD );
voxel[ 3 ] = NoiseToByte( a );
}
break;
}
case NoiseGenerationType.BigNoise :
{
float real = 0.5f + GetTiledNoise( noise, nX, nY, nZ, nX0, nY0, nZ0, nW, nH, nD );
float imag = 0.5f + GetTiledNoise( noise, nX + nW, nY + nH, nZ + nD, nX0, nY0, nZ0, nW, nH, nD );
// maxNoise = Math.Max( maxNoise, real );
// minNoise = Math.Min( minNoise, real );
double a = Math.PI + Math.PI * real;
voxel[ 0 ] = NoiseToByte( real );
voxel[ 1 ] = NoiseToByte( imag );
voxel[ 2 ] = ( byte )Utils.Clamp( ( Math.Sin( a ) + 1 ) * 127.5, 0, 255 );
voxel[ 3 ] = ( byte )Utils.Clamp( ( Math.Cos( a ) + 1 ) * 127.5, 0, 255 );
break;
}
default :
throw new NotSupportedException( string.Format( "Noise generation type \"{0}\" is not supported yet", parameters.GenerationType ) );
}
voxel += bytesPerVoxel;
}
}
}
}
/// <summary>
/// Sets up the build outputs
/// </summary>
/// <param name="scatteringTexture">Scattering texture data</param>
/// <param name="opticalDepthTexture">Optical depth texture data</param>
public AtmosphereBuildOutputs( Texture3dData scatteringTexture, Texture2dData opticalDepthTexture )
{
m_ScatteringTexture = scatteringTexture;
m_OpticalDepthTexture = opticalDepthTexture;
}
/// <summary>
/// Creates this texture from a texture data object
/// </summary>
public unsafe void Create( Texture3dData data )
{
m_Width = data.Width;
m_Height = data.Height;
m_Depth = data.Depth;
m_Format = data.Format;
m_Handle = OpenGlTextureHandle.CreateHandle( );
OpenGlTexture2dBuilder.TextureInfo info = OpenGlTexture2dBuilder.CheckTextureFormat( m_Format );
int target = Gl.GL_TEXTURE_3D;
int border = 0;
Gl.glEnable( target );
Gl.glBindTexture( target, m_Handle );
fixed ( void* bytes = data.Bytes )
{
Gl.glTexImage3D( target, 0, info.GlInternalFormat, m_Width, m_Height, m_Depth, border, info.GlFormat, info.GlType, new IntPtr( bytes ) );
}
}
