void Heightmap::CalculateNormals(Vertex *vertexArray)
{
// Estimate normals for interior nodes using central difference.
float invTwoDX = 1.0f / (2.0f*mCellSpacing);
float invTwoDZ = 1.0f / (2.0f*mCellSpacing);
for(UINT i = 2; i < mNumRows-1; ++i)
{
for(UINT j = 2; j < mNumCols-1; ++j)
{
float t = mHeightmap[(i-1)*mNumCols + j];
float b = mHeightmap[(i+1)*mNumCols + j];
float l = mHeightmap[i*mNumCols + j - 1];
float r = mHeightmap[i*mNumCols + j + 1];
D3DXVECTOR3 tanZ(0.0f, (t-b)*invTwoDZ, 1.0f);
D3DXVECTOR3 tanX(1.0f, (r-l)*invTwoDX, 0.0f);
D3DXVECTOR3 N;
D3DXVec3Cross(&N, &tanZ, &tanX);
D3DXVec3Normalize(&N, &N);
vertexArray[i*mNumCols+j].normal = N;
}
}
}
void Terrain::buildVB()
{
std::vector<TerrainVertex> vertices(mNumVertices);
float halfWidth = (mInfo.NumCols-1)*mInfo.CellSpacing*0.5f;
float halfDepth = (mInfo.NumRows-1)*mInfo.CellSpacing*0.5f;
float du = 1.0f / (mInfo.NumCols-1);
float dv = 1.0f / (mInfo.NumRows-1);
for(UINT i = 0; i < mInfo.NumRows; ++i)
{
float z = halfDepth - i*mInfo.CellSpacing;
for(UINT j = 0; j < mInfo.NumCols; ++j)
{
float x = -halfWidth + j*mInfo.CellSpacing;
float y = mHeightmap[i*mInfo.NumCols+j];
vertices[i*mInfo.NumCols+j].pos = D3DXVECTOR3(x, y, z);
vertices[i*mInfo.NumCols+j].normal = D3DXVECTOR3(0.0f, 1.0f, 0.0f);
// Stretch texture over grid.
vertices[i*mInfo.NumCols+j].texC.x = j*du;
vertices[i*mInfo.NumCols+j].texC.y = i*dv;
}
}
// Estimate normals for interior nodes using central difference.
float invTwoDX = 1.0f / (2.0f*mInfo.CellSpacing);
float invTwoDZ = 1.0f / (2.0f*mInfo.CellSpacing);
for(UINT i = 2; i < mInfo.NumRows-1; ++i)
{
for(UINT j = 2; j < mInfo.NumCols-1; ++j)
{
float t = mHeightmap[(i-1)*mInfo.NumCols + j];
float b = mHeightmap[(i+1)*mInfo.NumCols + j];
float l = mHeightmap[i*mInfo.NumCols + j - 1];
float r = mHeightmap[i*mInfo.NumCols + j + 1];
D3DXVECTOR3 tanZ(0.0f, (t-b)*invTwoDZ, 1.0f);
D3DXVECTOR3 tanX(1.0f, (r-l)*invTwoDX, 0.0f);
D3DXVECTOR3 N;
D3DXVec3Cross(&N, &tanZ, &tanX);
D3DXVec3Normalize(&N, &N);
vertices[i*mInfo.NumCols+j].normal = N;
}
}
D3D10_BUFFER_DESC vbd;
vbd.Usage = D3D10_USAGE_IMMUTABLE;
vbd.ByteWidth = sizeof(TerrainVertex) * mNumVertices;
vbd.BindFlags = D3D10_BIND_VERTEX_BUFFER;
vbd.CPUAccessFlags = 0;
vbd.MiscFlags = 0;
D3D10_SUBRESOURCE_DATA vinitData;
vinitData.pSysMem = &vertices[0];
HR(md3dDevice->CreateBuffer(&vbd, &vinitData, &mVB));
}
