private void CalculateTangentBinormal(DTempVertexType vertex1, DTempVertexType vertex2, DTempVertexType vertex3, out DVertexTempType tangent, out DVertexTempType binormal)
{
float[] vector1 = new float[3];
float[] vector2 = new float[3];
float[] tuVector = new float[2];
float[] tvVector = new float[2];
// Calculate the two vectors for this face.
vector1[0] = vertex2.x - vertex1.x;
vector1[1] = vertex2.y - vertex1.y;
vector1[2] = vertex2.z - vertex1.z;
vector2[0] = vertex3.x - vertex1.x;
vector2[1] = vertex3.y - vertex1.y;
vector2[2] = vertex3.z - vertex1.z;
// Calculate the tu and tv texture space vectors.
tuVector[0] = vertex2.tu - vertex1.tu;
tvVector[0] = vertex2.tv - vertex1.tv;
tuVector[1] = vertex3.tu - vertex1.tu;
tvVector[1] = vertex3.tv - vertex1.tv;
// Calculate the denominator of the tangent/binormal equation.
float den = 1.0f / (tuVector[0] * tvVector[1] - tuVector[1] * tvVector[0]);
// Calculate the cross products and multiply by the coefficient to get the tangent and binormal.
tangent.x = (tvVector[1] * vector1[0] - tvVector[0] * vector2[0]) * den;
tangent.y = (tvVector[1] * vector1[1] - tvVector[0] * vector2[1]) * den;
tangent.z = (tvVector[1] * vector1[2] - tvVector[0] * vector2[2]) * den;
binormal.x = (tuVector[0] * vector2[0] - tuVector[1] * vector1[0]) * den;
binormal.y = (tuVector[0] * vector2[1] - tuVector[1] * vector1[1]) * den;
binormal.z = (tuVector[0] * vector2[2] - tuVector[1] * vector1[2]) * den;
// Calculate the length of this normal.
float length = (float)Math.Sqrt((tangent.x * tangent.x) + (tangent.y * tangent.y) + (tangent.z * tangent.z));
// Normalize the normal and then store it
binormal.x = binormal.x / length;
binormal.y = binormal.y / length;
binormal.z = binormal.z / length;
}
private bool CalculateNormals()
{
// Create a temporary array to hold the un-normalized normal vectors.
int index;
float length;
Vector3 vertex1, vertex2, vertex3, vector1, vector2, sum;
DVertexTempType[] normals = new DVertexTempType[(m_TerrainHeight - 1) * (m_TerrainWidth - 1)];
// Go through all the faces in the mesh and calculate their normals.
for (int j = 0; j < (m_TerrainHeight - 1); j++)
{
for (int i = 0; i < (m_TerrainWidth - 1); i++)
{
int index1 = (j * m_TerrainHeight) + i;
int index2 = (j * m_TerrainHeight) + (i + 1);
int index3 = ((j + 1) * m_TerrainHeight) + i;
// Get three vertices from the face.
vertex1.X = HeightMap[index1].x;
vertex1.Y = HeightMap[index1].y;
vertex1.Z = HeightMap[index1].z;
vertex2.X = HeightMap[index2].x;
vertex2.Y = HeightMap[index2].y;
vertex2.Z = HeightMap[index2].z;
vertex3.X = HeightMap[index3].x;
vertex3.Y = HeightMap[index3].y;
vertex3.Z = HeightMap[index3].z;
// Calculate the two vectors for this face.
vector1 = vertex1 - vertex3;
vector2 = vertex3 - vertex2;
index = (j * (m_TerrainHeight - 1)) + i;
// Calculate the cross product of those two vectors to get the un-normalized value for this face normal.
Vector3 vecTestCrossProduct = Vector3.Cross(vector1, vector2);
normals[index].x = vecTestCrossProduct.X;
normals[index].y = vecTestCrossProduct.Y;
normals[index].z = vecTestCrossProduct.Z;
}
}
// Now go through all the vertices and take an average of each face normal
// that the vertex touches to get the averaged normal for that vertex.
for (int j = 0; j < m_TerrainHeight; j++)
{
for (int i = 0; i < m_TerrainWidth; i++)
{
// Initialize the sum.
sum = Vector3.Zero;
// Initialize the count.
int count = 9;
// Bottom left face.
if (((i - 1) >= 0) && ((j - 1) >= 0))
{
index = ((j - 1) * (m_TerrainHeight - 1)) + (i - 1);
sum[0] += normals[index].x;
sum[1] += normals[index].y;
sum[2] += normals[index].z;
count++;
}
// Bottom right face.
if ((i < (m_TerrainWidth - 1)) && ((j - 1) >= 0))
{
index = ((j - 1) * (m_TerrainHeight - 1)) + i;
sum[0] += normals[index].x;
sum[1] += normals[index].y;
sum[2] += normals[index].z;
count++;
}
// Upper left face.
if (((i - 1) >= 0) && (j < (m_TerrainHeight - 1)))
{
index = (j * (m_TerrainHeight - 1)) + (i - 1);
sum[0] += normals[index].x;
sum[1] += normals[index].y;
sum[2] += normals[index].z;
count++;
}
// Upper right face.
if ((i < (m_TerrainWidth - 1)) && (j < (m_TerrainHeight - 1)))
{
index = (j * (m_TerrainHeight - 1)) + i;
sum.X += normals[index].x;
sum.Y += normals[index].y;
sum.Z += normals[index].z;
count++;
}
// Take the average of the faces touching this vertex.
sum.X = (sum.X / (float)count);
sum.Y = (sum.Y / (float)count);
sum.Z = (sum.Z / (float)count);
// Calculate the length of this normal.
length = (float)Math.Sqrt((sum.X * sum.X) + (sum.Y * sum.Y) + (sum.Z * sum.Z));
// Get an index to the vertex location in the height map array.
index = (j * m_TerrainHeight) + i;
// Normalize the final shared normal for this vertex and store it in the height map array.
DHeightMapType editHeightMap = HeightMap[index];
editHeightMap.nx = (sum.X / length);
editHeightMap.ny = (sum.Y / length);
editHeightMap.nz = (sum.Z / length);
HeightMap[index] = editHeightMap;
}
}
// Release the temporary normals.
normals = null;
return(true);
}
private void CalculateTerrainVectors()
{
// Calculate the number of faces in the terrain model.
int faceCount = VertexCount / 3;
// Initialize the index to the model data.
int index = 0;
DTempVertexType vertex1, vertex2, vertex3;
DVertexTempType tangent = new DVertexTempType();
DVertexTempType binormal = new DVertexTempType();
// Go through all the faces and calculate the the tangent, binormal, and normal vectors.
for (int i = 0; i < faceCount; i++)
{
// Get the three vertices for this face from the terrain model.
vertex1.x = TerrainModel[index].x;
vertex1.y = TerrainModel[index].y;
vertex1.z = TerrainModel[index].z;
vertex1.tu = TerrainModel[index].tu;
vertex1.tv = TerrainModel[index].tv;
vertex1.nx = TerrainModel[index].nx;
vertex1.ny = TerrainModel[index].ny;
vertex1.nz = TerrainModel[index].nz;
index++;
vertex2.x = TerrainModel[index].x;
vertex2.y = TerrainModel[index].y;
vertex2.z = TerrainModel[index].z;
vertex2.tu = TerrainModel[index].tu;
vertex2.tv = TerrainModel[index].tv;
vertex2.nx = TerrainModel[index].nx;
vertex2.ny = TerrainModel[index].ny;
vertex2.nz = TerrainModel[index].nz;
index++;
vertex3.x = TerrainModel[index].x;
vertex3.y = TerrainModel[index].y;
vertex3.z = TerrainModel[index].z;
vertex3.tu = TerrainModel[index].tu;
vertex3.tv = TerrainModel[index].tv;
vertex3.nx = TerrainModel[index].nx;
vertex3.ny = TerrainModel[index].ny;
vertex3.nz = TerrainModel[index].nz;
index++;
/// MAKE SUEW that the tangent nad Binoemals calculated are being sent intot he model after the method below.
// Calculate the tangent and binormal of that face.
CalculateTangentBinormal(vertex1, vertex2, vertex3, out tangent, out binormal);
// Store the tangent and binormal for this face back in the model structure.
TerrainModel[index - 1].tx = tangent.x;
TerrainModel[index - 1].ty = tangent.y;
TerrainModel[index - 1].tz = tangent.z;
TerrainModel[index - 1].bx = binormal.x;
TerrainModel[index - 1].by = binormal.y;
TerrainModel[index - 1].bz = binormal.z;
TerrainModel[index - 2].tx = tangent.x;
TerrainModel[index - 2].ty = tangent.y;
TerrainModel[index - 2].tz = tangent.z;
TerrainModel[index - 2].bx = binormal.x;
TerrainModel[index - 2].by = binormal.y;
TerrainModel[index - 2].bz = binormal.z;
TerrainModel[index - 3].tx = tangent.x;
TerrainModel[index - 3].ty = tangent.y;
TerrainModel[index - 3].tz = tangent.z;
TerrainModel[index - 3].bx = binormal.x;
TerrainModel[index - 3].by = binormal.y;
TerrainModel[index - 3].bz = binormal.z;
}
}
