/// <summary>
/// <para>Reads in a 2D texture in RGBM format, and extracts the cube faces.</para>
/// <para>It also generates a Spherical Harmonic from the input, to approximate indirect lighting</para>
/// </summary>
public RgbmCubeMap(Texture2D sourceRgbmImage2D, Texture2D sourceRgbmAlphaImage2D, float maxRange)
{
//the two textures represent the RGB and M values of an RGBM texture. They have
//been separated to make it easier to view their colour channels.
//This is somewhat wasteful however. Normally it would be wise to combine them into one texture.
if (sourceRgbmImage2D == null || sourceRgbmAlphaImage2D == null)
throw new ArgumentNullException();
if (sourceRgbmImage2D.Width != sourceRgbmImage2D.Height * 6 ||
sourceRgbmAlphaImage2D.Width != sourceRgbmImage2D.Width ||
sourceRgbmAlphaImage2D.Height != sourceRgbmImage2D.Height)
throw new ArgumentException("Invalid size"); //expected to have 6 cube faces
if (sourceRgbmImage2D.Format != SurfaceFormat.Color ||
sourceRgbmAlphaImage2D.Format != SurfaceFormat.Color)
throw new ArgumentException("Unexpected image format");
if (maxRange <= 0.0f)
throw new ArgumentException("MaxRange");
this.MaxRange = maxRange;
//extract the RGB pixels
Color[] pixelDataRGB = new Color[sourceRgbmImage2D.Width * sourceRgbmImage2D.Height];
sourceRgbmImage2D.GetData(pixelDataRGB);
//extract the M pixels
Color[] pixelDataM = new Color[sourceRgbmAlphaImage2D.Width * sourceRgbmAlphaImage2D.Height];
sourceRgbmAlphaImage2D.GetData(pixelDataM);
//at this point, the source textures are no longer needed
//extract the faces from the cubemap,
//and generate a spherical harmonic based off it's colours
//width/height of each face of the cubemap
int cubeFaceSize = sourceRgbmImage2D.Height;
this.SphericalHarmonic = new Xen.Ex.SphericalHarmonicL2RGB();
this.cubeMap = new TextureCube(sourceRgbmImage2D.GraphicsDevice, cubeFaceSize, false, SurfaceFormat.Color);
int textureLineStride = sourceRgbmImage2D.Width;
//storage for the decoded cubemap faces
Vector3[][] cubeFaces = new Vector3[6][];
//temporary storage of a single face of the cube
Color[] singleFaceRGBM = new Color[cubeFaceSize * cubeFaceSize];
//extract the 6 faces of the cubemap.
for (int face = 0; face < 6; face++)
{
CubeMapFace faceId = (CubeMapFace)face;
//cube face data
Vector3[] singleFaceRGB = new Vector3[cubeFaceSize * cubeFaceSize];
cubeFaces[face] = singleFaceRGB;
//each face is stored next to each other in the 2D texture
int startPixel = cubeFaceSize * face;
//copy the face from the 2D texture data into singleFace
int writeIndex = 0;
int readIndex = startPixel;
for (int y = 0; y < cubeFaceSize; y++) // each hoizontal line
{
for (int x = 0; x < cubeFaceSize; x++) // each pixel in the line
{
Color encodedRgb = pixelDataRGB[readIndex + x];
Color encodedM = pixelDataM[readIndex + x];
//combine to get the RGBM value
Color rgbm = new Color(encodedRgb.R, encodedRgb.G, encodedRgb.B, encodedM.R);
//decode the pixel
Vector3 rgb = RgbmTools.DecodeRGBM(rgbm, maxRange);
//convert to linear
rgb = rgb * rgb;
//store
singleFaceRGB[writeIndex + x] = rgb;
singleFaceRGBM[writeIndex + x] = rgbm;
}
//jump to the next line
readIndex += textureLineStride;
writeIndex += cubeFaceSize;
}
//write the pixels into the cubemap
cubeMap.SetData(faceId, singleFaceRGBM);
}
//Generate the SH from the cubemap faces
this.SphericalHarmonic = Xen.Ex.SphericalHarmonicL2RGB.GenerateSphericalHarmonicFromCubeMap(cubeFaces);
}
private static Xen.Ex.SphericalHarmonicL2RGB ExtractSphericalHarmonicForCubeFace(Matrix faceTransform, Vector3[] colourDataRGB, int faceSize)
{
Xen.Ex.SphericalHarmonicL2RGB sh = new Xen.Ex.SphericalHarmonicL2RGB();
//For each pixel in the face, generate it's SH contribution.
//Treat each pixel in the cube as a light source, which gets added to the SH.
//This is used to generate an indirect lighting SH for the scene.
//See the remarks in SphericalHarmonicL2RGB for more detals.
float directionStep = 2.0f / (faceSize - 1.0f);
int pixelIndex = 0;
float dirY = 1.0f;
for (int y = 0; y < faceSize; y++)
{
Xen.Ex.SphericalHarmonicL2RGB lineSh = new Xen.Ex.SphericalHarmonicL2RGB();
float dirX = -1.0f;
for (int x = 0; x < faceSize; x++)
{
//the direction to the pixel in the cube
Vector3 direction = new Vector3(dirX, dirY, 1);
Vector3.TransformNormal(ref direction, ref faceTransform, out direction);
//length of the direction vector
float length = direction.Length();
//approximate area of the pixel (pixels close to the cube edges appear smaller when projected)
float weight = 1.0f / length;
//normalise:
direction.X *= weight;
direction.Y *= weight;
direction.Z *= weight;
//decode the RGBM colour
Vector3 rgb = colourDataRGB[pixelIndex++];
//Add it to the SH
lineSh.AddLight(ref rgb, ref direction, weight);
dirX += directionStep;
}
//average the SH
if (lineSh.Weighting > 0)
lineSh /= lineSh.Weighting;
//add the line to the full SH
//(SH is generated line by line to ease problems with floating point accuracy loss)
sh += lineSh;
dirY -= directionStep;
}
if (sh.Weighting > 0)
sh /= sh.Weighting;
return sh;
}
private static Xen.Ex.SphericalHarmonicL2RGB ExtractSphericalHarmonicForCubeFace(Matrix faceTransform, Vector3[] colourDataRGB, int faceSize)
{
Xen.Ex.SphericalHarmonicL2RGB sh = new Xen.Ex.SphericalHarmonicL2RGB();
//For each pixel in the face, generate it's SH contribution.
//Treat each pixel in the cube as a light source, which gets added to the SH.
//This is used to generate an indirect lighting SH for the scene.
//See the remarks in SphericalHarmonicL2RGB for more detals.
float directionStep = 2.0f / (faceSize - 1.0f);
int pixelIndex = 0;
float dirY = 1.0f;
for (int y = 0; y < faceSize; y++)
{
Xen.Ex.SphericalHarmonicL2RGB lineSh = new Xen.Ex.SphericalHarmonicL2RGB();
float dirX = -1.0f;
for (int x = 0; x < faceSize; x++)
{
//the direction to the pixel in the cube
Vector3 direction = new Vector3(dirX, dirY, 1);
Vector3.TransformNormal(ref direction, ref faceTransform, out direction);
//length of the direction vector
float length = direction.Length();
//approximate area of the pixel (pixels close to the cube edges appear smaller when projected)
float weight = 1.0f / length;
//normalise:
direction.X *= weight;
direction.Y *= weight;
direction.Z *= weight;
//decode the RGBM colour
Vector3 rgb = colourDataRGB[pixelIndex++];
//Add it to the SH
lineSh.AddLight(ref rgb, ref direction, weight);
dirX += directionStep;
}
//average the SH
if (lineSh.Weighting > 0)
{
lineSh /= lineSh.Weighting;
}
//add the line to the full SH
//(SH is generated line by line to ease problems with floating point accuracy loss)
sh += lineSh;
dirY -= directionStep;
}
if (sh.Weighting > 0)
{
sh /= sh.Weighting;
}
return(sh);
}
/// <summary>
/// <para>Reads in a 2D texture in RGBM format, and extracts the cube faces.</para>
/// <para>It also generates a Spherical Harmonic from the input, to approximate indirect lighting</para>
/// </summary>
public RgbmCubeMap(Texture2D sourceRgbmImage2D, Texture2D sourceRgbmAlphaImage2D, float maxRange)
{
//the two textures represent the RGB and M values of an RGBM texture. They have
//been separated to make it easier to view their colour channels.
//This is somewhat wasteful however. Normally it would be wise to combine them into one texture.
if (sourceRgbmImage2D == null || sourceRgbmAlphaImage2D == null)
{
throw new ArgumentNullException();
}
if (sourceRgbmImage2D.Width != sourceRgbmImage2D.Height * 6 ||
sourceRgbmAlphaImage2D.Width != sourceRgbmImage2D.Width ||
sourceRgbmAlphaImage2D.Height != sourceRgbmImage2D.Height)
{
throw new ArgumentException("Invalid size"); //expected to have 6 cube faces
}
if (sourceRgbmImage2D.Format != SurfaceFormat.Color ||
sourceRgbmAlphaImage2D.Format != SurfaceFormat.Color)
{
throw new ArgumentException("Unexpected image format");
}
if (maxRange <= 0.0f)
{
throw new ArgumentException("MaxRange");
}
this.MaxRange = maxRange;
//extract the RGB pixels
Color[] pixelDataRGB = new Color[sourceRgbmImage2D.Width * sourceRgbmImage2D.Height];
sourceRgbmImage2D.GetData(pixelDataRGB);
//extract the M pixels
Color[] pixelDataM = new Color[sourceRgbmAlphaImage2D.Width * sourceRgbmAlphaImage2D.Height];
sourceRgbmAlphaImage2D.GetData(pixelDataM);
//at this point, the source textures are no longer needed
//extract the faces from the cubemap,
//and generate a spherical harmonic based off it's colours
//width/height of each face of the cubemap
int cubeFaceSize = sourceRgbmImage2D.Height;
this.SphericalHarmonic = new Xen.Ex.SphericalHarmonicL2RGB();
this.cubeMap = new TextureCube(sourceRgbmImage2D.GraphicsDevice, cubeFaceSize, 1, TextureUsage.None, SurfaceFormat.Color);
int textureLineStride = sourceRgbmImage2D.Width;
//storage for the decoded cubemap faces
Vector3[][] cubeFaces = new Vector3[6][];
//temporary storage of a single face of the cube
Color[] singleFaceRGBM = new Color[cubeFaceSize * cubeFaceSize];
//extract the 6 faces of the cubemap.
for (int face = 0; face < 6; face++)
{
CubeMapFace faceId = (CubeMapFace)face;
//cube face data
Vector3[] singleFaceRGB = new Vector3[cubeFaceSize * cubeFaceSize];
cubeFaces[face] = singleFaceRGB;
//each face is stored next to each other in the 2D texture
int startPixel = cubeFaceSize * face;
//copy the face from the 2D texture data into singleFace
int writeIndex = 0;
int readIndex = startPixel;
for (int y = 0; y < cubeFaceSize; y++) // each hoizontal line
{
for (int x = 0; x < cubeFaceSize; x++) // each pixel in the line
{
Color encodedRgb = pixelDataRGB[readIndex + x];
Color encodedM = pixelDataM[readIndex + x];
//combine to get the RGBM value
Color rgbm = new Color(encodedRgb.R, encodedRgb.G, encodedRgb.B, encodedM.R);
//decode the pixel
Vector3 rgb = RgbmTools.DecodeRGBM(rgbm, maxRange);
//convert to linear
rgb = rgb * rgb;
//store
singleFaceRGB[writeIndex + x] = rgb;
singleFaceRGBM[writeIndex + x] = rgbm;
}
//jump to the next line
readIndex += textureLineStride;
writeIndex += cubeFaceSize;
}
//write the pixels into the cubemap
cubeMap.SetData(faceId, singleFaceRGBM);
}
//Generate the SH from the cubemap faces
this.SphericalHarmonic = Xen.Ex.SphericalHarmonicL2RGB.GenerateSphericalHarmonicFromCubeMap(cubeFaces);
}