void CShadow::onTick(float fElapsedTime) {
for (unsigned int i(0); i < m_vMesh.size(); i++) {
D3DXVECTOR3 vSun(*m_pSun); D3DXMATRIX mInv;
D3DXMatrixInverse(&mInv, NULL, m_vMat[i]);
D3DXVec3TransformCoord(&vSun, &vSun, &mInv);
ID3DXMesh* pMesh;
m_vMesh[i]->CloneMeshFVF(m_vMesh[i]->GetOptions(), D3DFVF_XYZ,
CDirect3D::getInstance()->GetD3D9Device(), &pMesh);
D3DXVECTOR3 *pVertices, *pVolume;
WORD* pIndices;
pMesh->LockVertexBuffer(NULL, (void**) &pVertices);
pMesh->LockIndexBuffer(NULL, (void**) &pIndices);
DWORD dwFaces(pMesh->GetNumFaces());
WORD* pEdges = new WORD[dwFaces*3*2];
DWORD dwEdges(0);
for (DWORD j(0); j < dwFaces; j++) {
WORD wFace0 = pIndices[j*3];
WORD wFace1 = pIndices[j*3+1];
WORD wFace2 = pIndices[j*3+2];
D3DXVECTOR3 v0 = pVertices[wFace0];
D3DXVECTOR3 v1 = pVertices[wFace1];
D3DXVECTOR3 v2 = pVertices[wFace2];
D3DXVECTOR3 vCross1(v2-v1);
D3DXVECTOR3 vCross2(v1-v0);
D3DXVECTOR3 vNormal;
D3DXVec3Cross(&vNormal, &vCross1, &vCross2);
if (D3DXVec3Dot(&vNormal, m_pSun) > 0.f) {
AddEdge(pEdges, dwEdges, wFace0, wFace1);
AddEdge(pEdges, dwEdges, wFace1, wFace2);
AddEdge(pEdges, dwEdges, wFace2, wFace0);
}
}
m_dwTriangles[i] = dwEdges*2;
m_vVB[i]->Lock(0, sizeof(D3DXVECTOR3)*m_dwTriangles[i]*3, (void**) &pVolume, NULL);
// some (solvable, but expensive) issues here:
// (view port related) direction undetermined for segment v1 - v2,
// so CULL_CW doesn't necessarily mean 'back side'.
for (DWORD j(0); j < dwEdges; j++) {
D3DXVECTOR3 v1 = pVertices[pEdges[2*j+0]];
D3DXVECTOR3 v2 = pVertices[pEdges[2*j+1]];
D3DXVECTOR3 v3 = (v1 - vSun);
D3DXVECTOR3 v4 = (v2 - vSun);
pVolume[j*6] = v3;
pVolume[j*6+1] = v1;
pVolume[j*6+2] = v4; // 1 2
pVolume[j*6+3] = v4; // |\|
pVolume[j*6+4] = v1; // 3 4
pVolume[j*6+5] = v2;
}
m_vVB[i]->Unlock();
pMesh->UnlockVertexBuffer();
pMesh->UnlockIndexBuffer();
Safe_Release(pMesh);
Safe_Delete_Array(pEdges);
}
}
//-----------------------------------------------------------------------------
// Name: buildShadowVolume()
// Desc: Takes a mesh as input, and uses it to build a shadow volume. The
// technique used considers each triangle of the mesh, and adds it's
// edges to a temporary list. The edge list is maintained, such that
// only silohuette edges are kept. Finally, the silohuette edges are
// extruded to make the shadow volume vertex list.
//-----------------------------------------------------------------------------
HRESULT CShadowVolume::BuildShadowVolume(LPD3DXMESH pMesh, D3DXVECTOR3 vLight)
{
// pMesh的顶点结构
struct MeshVertex {
D3DXVECTOR3 p;
D3DXVECTOR3 n;
float u, v;
};
MeshVertex *pVertices;
WORD *pIndices;
// 锁缓存
pMesh->LockVertexBuffer(0L, (LPVOID*)&pVertices);
pMesh->LockIndexBuffer(0L, (LPVOID*)&pIndices);
DWORD dwNumFaces = pMesh->GetNumFaces();
// 分配一个临时的索引数组
WORD *pEdges = new WORD[dwNumFaces * 6];
if (pEdges == NULL)
{
pMesh->UnlockVertexBuffer();
pMesh->UnlockIndexBuffer();
return E_OUTOFMEMORY;
}
DWORD dwNumEdges = 0;
// 对每个片面进行计算
for (DWORD i = 0; i < dwNumFaces; ++i)
{
WORD wFace0 = pIndices[3 * i + 0];
WORD wFace1 = pIndices[3 * i + 1];
WORD wFace2 = pIndices[3 * i + 2];
// 一个面的三个顶点坐标
D3DXVECTOR3 v0 = pVertices[wFace0].p;
D3DXVECTOR3 v1 = pVertices[wFace1].p;
D3DXVECTOR3 v2 = pVertices[wFace2].p;
// 计算法线是否向光
D3DXVECTOR3 vCross1(v2 - v1);
D3DXVECTOR3 vCross2(v1 - v0);
D3DXVECTOR3 vNormal;
D3DXVec3Cross(&vNormal, &vCross1, &vCross2);
if (D3DXVec3Dot(&vNormal, &vLight) >= 0.0f)
{
AddEdge(pEdges, dwNumEdges, wFace0, wFace1);
AddEdge(pEdges, dwNumEdges, wFace1, wFace2);
AddEdge(pEdges, dwNumEdges, wFace2, wFace0);
}
}
// pEdges中仅剩pMesh的边缘顶点，对每条边的两个顶点按光照的方向进行延伸
// 最终构建一个完整的阴影体
for (DWORD i = 0; i < dwNumEdges; ++i)
{
D3DXVECTOR3 v1 = pVertices[pEdges[2 * i + 0]].p;
D3DXVECTOR3 v2 = pVertices[pEdges[2 * i + 1]].p;
D3DXVECTOR3 v3 = v1 + vLight * 200;
D3DXVECTOR3 v4 = v2 + vLight * 200;
// 封边操作
m_pVertices[m_dwNumVertices++] = v1;
m_pVertices[m_dwNumVertices++] = v2;
m_pVertices[m_dwNumVertices++] = v3;
m_pVertices[m_dwNumVertices++] = v2;
m_pVertices[m_dwNumVertices++] = v4;
m_pVertices[m_dwNumVertices++] = v3;
}
// Delete the temporary edge list
delete[] pEdges;
// Unlock the geometry buffers
pMesh->UnlockVertexBuffer();
pMesh->UnlockIndexBuffer();
return S_OK;
}
void Sombra::ConstruirSombra(LPD3DXMESH pMesh, D3DXVECTOR3 vLight)
{
// Note: the MeshVertex format depends on the FVF of the mesh
struct MeshVertex { D3DXVECTOR3 p, n;
DWORD diffuse;
float tu,tv; };
MeshVertex *pVertices;
WORD *pIndices;
// Lock the geometry buffers
pMesh->LockVertexBuffer( 0L, (LPVOID*)&pVertices );
pMesh->LockIndexBuffer( 0L, (LPVOID*)&pIndices );
DWORD dwNumFaces = pMesh->GetNumFaces();
// Allocate a temporary edge list
WORD *pEdges = new WORD[dwNumFaces*6];
if( pEdges == NULL )
{
pMesh->UnlockVertexBuffer();
pMesh->UnlockIndexBuffer();
return ;
}
DWORD dwNumEdges = 0;
// For each face
for( DWORD i = 0; i < dwNumFaces; ++i )
{
WORD wFace0 = pIndices[3*i+0];
WORD wFace1 = pIndices[3*i+1];
WORD wFace2 = pIndices[3*i+2];
D3DXVECTOR3 v0 = pVertices[wFace0].p;
D3DXVECTOR3 v1 = pVertices[wFace1].p;
D3DXVECTOR3 v2 = pVertices[wFace2].p;
// Transform vertices or transform light?
D3DXVECTOR3 vCross1(v2-v1);
D3DXVECTOR3 vCross2(v1-v0);
D3DXVECTOR3 vNormal;
D3DXVec3Cross( &vNormal, &vCross1, &vCross2 );
if( D3DXVec3Dot( &vNormal, &vLight ) >= 0.0f )
{
InsertarSegmento( pEdges, dwNumEdges, wFace0, wFace1 );
InsertarSegmento( pEdges, dwNumEdges, wFace1, wFace2 );
InsertarSegmento( pEdges, dwNumEdges, wFace2, wFace0 );
}
}
// Se construyen las caras de la sombra extrudando los segmentos en la dirección
// de la luz y una longitud 10 veces la del vector luz.
for( i = 0; i < dwNumEdges; ++i )
{
D3DXVECTOR3 v1 = pVertices[pEdges[2*i+0]].p;
D3DXVECTOR3 v2 = pVertices[pEdges[2*i+1]].p;
D3DXVECTOR3 v3 = v1 - vLight/10;
D3DXVECTOR3 v4 = v2 - vLight/10;
// Add a quad (two triangles) to the vertex list
m_pVertices[m_dwNumVertices++] = v1;
m_pVertices[m_dwNumVertices++] = v2;
m_pVertices[m_dwNumVertices++] = v3;
m_pVertices[m_dwNumVertices++] = v2;
m_pVertices[m_dwNumVertices++] = v4;
m_pVertices[m_dwNumVertices++] = v3;
}
// Delete the temporary edge list
delete[] pEdges;
// Unlock the geometry buffers
pMesh->UnlockVertexBuffer();
pMesh->UnlockIndexBuffer();
}
