private void GenerateTerrainNormals(VertexPositionNormalTangentBinormalTexture[] vertices, int[] indices)
{
for (int i = 0; i < indices.Length; i += 3)
{
Vector3 v1 = vertices[indices[i]].Position;
Vector3 v2 = vertices[indices[i + 1]].Position;
Vector3 v3 = vertices[indices[i + 2]].Position;
Vector3 vu = v3 - v1;
Vector3 vt = v2 - v1;
Vector3 normal = Vector3.Cross(vu, vt);
normal.Normalize();
vertices[indices[i]].Normal += normal;
vertices[indices[i + 1]].Normal += normal;
vertices[indices[i + 2]].Normal += normal;
}
for (int i = 0; i < vertices.Length; i++)
{
vertices[i].Normal.Normalize();
}
}
/**
* Generate terrain mesh vertices and indices
* The vertex is currently VertexPositionNormalTangentBinormalTexture
*/
private VertexPositionNormalTangentBinormalTexture[] GenerateTerrainVertices(int[] terrainIndices)
{
float halfTerrainWidth = (vertexCountX - 1) * blockScale * 0.5f;
float halfTerrainDepth = (vertexCountZ - 1) * blockScale * 0.5f;
// Texture coordinates
float tu = 0;
float tv = 0;
float tuDerivative = 1.0f / (vertexCountX - 1);
float tvDerivative = 1.0f / (vertexCountZ - 1);
int vertexCount = 0;
VertexPositionNormalTangentBinormalTexture[] vertices =
new VertexPositionNormalTangentBinormalTexture[vertexCountX * vertexCountZ];
// Set vertices position and texture coordinate
for (float i = -halfTerrainDepth; i <= halfTerrainDepth; i += blockScale)
{
tu = 0.0f;
for (float j = -halfTerrainWidth; j <= halfTerrainWidth; j += blockScale)
{
vertices[vertexCount].Position = new Vector3(j, heightMap[vertexCount].R * heightScale, i);
vertices[vertexCount].TextureCoordinate = new Vector2(tu, tv);
tu += tuDerivative;
vertexCount++;
}
tv += tvDerivative;
}
// Generate vertice's normal, tangent and binormal
GenerateTerrainNormals(vertices, terrainIndices);
GenerateTerrainTangentBinormal(vertices, terrainIndices);
return vertices;
}
public void GenerateTerrainTangentBinormal(VertexPositionNormalTangentBinormalTexture[] vertices, int[] indices)
{
for (int i = 0; i < vertexCountZ; i++)
{
for (int j = 0; j < vertexCountX; j++)
{
int vertexIndex = j + i * vertexCountX;
Vector3 v1 = vertices[vertexIndex].Position;
if (j < vertexCountX - 1)
{
Vector3 v2 = vertices[vertexIndex + 1].Position;
vertices[vertexIndex].Tanget = (v2 - v1);
}
else
{
Vector3 v2 = vertices[vertexIndex - 1].Position;
vertices[vertexIndex].Tanget = (v1 - v2);
}
vertices[vertexIndex].Tanget.Normalize();
vertices[vertexIndex].Binormal = Vector3.Cross(vertices[vertexIndex].Tanget, vertices[vertexIndex].Normal);
}
}
}
