shadowvolume.cpp

《3D游戏编程》随书光盘 12章: 设计阴影的多种技巧, 有详细源代码

//-----------------------------------------------------------------------------
// File: ShadowVolume.cpp
//
// Desc: Example code showing how to use stencil buffers to implement shadow
//       volumes.
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#define STRICT
#include <Windows.h>
#include <commctrl.h>
#include <math.h>
#include <stdio.h>
#include <D3DX9.h>
#include "DXUtil.h"
#include "D3DEnumeration.h"
#include "D3DSettings.h"
#include "D3DApp.h"
#include "D3DUtil.h"
#include "D3DFile.h"
#include "D3DFont.h"




//-----------------------------------------------------------------------------
// External definitions and prototypes
//-----------------------------------------------------------------------------
inline DWORD FtoDW( FLOAT f ) { return *((DWORD*)&f); }

struct VERTEX
{
    D3DXVECTOR3 p;
    D3DXVECTOR3 n;
    FLOAT       tu, tv;

    static const DWORD FVF;
};
const DWORD VERTEX::FVF = D3DFVF_XYZ | D3DFVF_NORMAL | D3DFVF_TEX1;

struct SHADOWVERTEX
{
    D3DXVECTOR4 p;
    D3DCOLOR    color;

    static const DWORD FVF;
};
const DWORD SHADOWVERTEX::FVF = D3DFVF_XYZRHW | D3DFVF_DIFFUSE;



//-----------------------------------------------------------------------------
// Name: struct ShadowVolume
// Desc: A shadow volume object
//-----------------------------------------------------------------------------
class ShadowVolume
{
    D3DXVECTOR3 m_pVertices[32000]; // Vertex data for rendering shadow volume
    DWORD       m_dwNumVertices;

public:
    VOID    Reset() { m_dwNumVertices = 0L; }
    HRESULT BuildFromMesh( LPD3DXMESH pObject, D3DXVECTOR3 vLight );
    HRESULT Render( LPDIRECT3DDEVICE9 pd3dDevice );
};




//-----------------------------------------------------------------------------
// Name: class CMyD3DApplication
// Desc: Application class. The base class (CD3DApplication) provides the 
//       generic functionality needed in all Direct3D samples. CMyD3DApplication 
//       adds functionality specific to this sample program.
//-----------------------------------------------------------------------------
class CMyD3DApplication : public CD3DApplication
{
    CD3DFont*     m_pFont;
    CD3DArcBall   m_ArcBall;

    CD3DMesh*     m_pAirplane;
    CD3DMesh*     m_pTerrainObject;
    ShadowVolume* m_pShadowVolume;

    D3DXMATRIXA16    m_matObjectMatrix;
    D3DXMATRIXA16    m_matTerrainMatrix;

    LPDIRECT3DVERTEXBUFFER9 m_pBigSquareVB;
    HRESULT DrawShadow();
    HRESULT RenderShadow();

    HRESULT ConfirmDevice( D3DCAPS9*, DWORD, D3DFORMAT, D3DFORMAT );

protected:
    HRESULT OneTimeSceneInit();
    HRESULT InitDeviceObjects();
    HRESULT RestoreDeviceObjects();
    HRESULT InvalidateDeviceObjects();
    HRESULT DeleteDeviceObjects();
    HRESULT Render();
    HRESULT FrameMove();
    HRESULT FinalCleanup();

public:
    LRESULT MsgProc( HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam );

    CMyD3DApplication();
};




//-----------------------------------------------------------------------------
// Name: WinMain()
// Desc: Entry point to the program. Initializes everything, and goes into a
//       message-processing loop. Idle time is used to render the scene.
//-----------------------------------------------------------------------------
INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR, INT )
{
    CMyD3DApplication d3dApp;

    InitCommonControls();
    if( FAILED( d3dApp.Create( hInst ) ) )
        return 0;

    return d3dApp.Run();
}




//-----------------------------------------------------------------------------
// Name:
// Desc:
//-----------------------------------------------------------------------------
HRESULT ShadowVolume::Render( LPDIRECT3DDEVICE9 pd3dDevice )
{
    pd3dDevice->SetFVF( D3DFVF_XYZ );

    return pd3dDevice->DrawPrimitiveUP( D3DPT_TRIANGLELIST, m_dwNumVertices/3,
                                        m_pVertices, sizeof(D3DXVECTOR3) );
}




//-----------------------------------------------------------------------------
// Name: AddEdge()
// Desc: Adds an edge to a list of silohuette edges of a shadow volume.
//-----------------------------------------------------------------------------
VOID AddEdge( WORD* pEdges, DWORD& dwNumEdges, WORD v0, WORD v1 )
{
    // Remove interior edges (which appear in the list twice)
    for( DWORD i=0; i < dwNumEdges; i++ )
    {
        if( ( pEdges[2*i+0] == v0 && pEdges[2*i+1] == v1 ) ||
            ( pEdges[2*i+0] == v1 && pEdges[2*i+1] == v0 ) )
        {
            if( dwNumEdges > 1 )
            {
                pEdges[2*i+0] = pEdges[2*(dwNumEdges-1)+0];
                pEdges[2*i+1] = pEdges[2*(dwNumEdges-1)+1];
            }
            dwNumEdges--;
            return;
        }
    }

    pEdges[2*dwNumEdges+0] = v0;
    pEdges[2*dwNumEdges+1] = v1;
    dwNumEdges++;
}




//-----------------------------------------------------------------------------
// Name: BuildFromMesh()
// Desc: Takes a mesh as input, and uses it to build a shadowvolume. 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 ShadowVolume::BuildFromMesh( LPD3DXMESH pMesh, D3DXVECTOR3 vLight )
{
    // Note: the MESHVERTEX format depends on the FVF of the mesh
    struct MESHVERTEX { D3DXVECTOR3 p, n; 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 E_OUTOFMEMORY;
    }
    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 )
        {
            AddEdge( pEdges, dwNumEdges, wFace0, wFace1 );
            AddEdge( pEdges, dwNumEdges, wFace1, wFace2 );
            AddEdge( pEdges, dwNumEdges, wFace2, wFace0 );
        }
    }

    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();

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: CMyD3DApplication()
// Desc: Application constructor. Sets attributes for the app.
//-----------------------------------------------------------------------------
CMyD3DApplication::CMyD3DApplication()
{
    m_strWindowTitle    = _T("ShadowVolume: RealTime Shadows Using The StencilBuffer");
    m_d3dEnumeration.AppUsesDepthBuffer = TRUE;
    m_d3dEnumeration.AppMinDepthBits = 16;
    m_d3dEnumeration.AppMinStencilBits = 4;
    m_bShowCursorWhenFullscreen = TRUE;

    m_pFont           = new CD3DFont( _T("Arial"), 12, D3DFONT_BOLD );
    m_pAirplane       = new CD3DMesh();
    m_pTerrainObject  = new CD3DMesh();
    m_pShadowVolume   = NULL;
    m_pBigSquareVB    = NULL;
}




//-----------------------------------------------------------------------------
// Name: OneTimeSceneInit()
// Desc: Called during initial app startup, this function performs all the
//       permanent initialization.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::OneTimeSceneInit()
{
    // Construct a shadow volume object;
    m_pShadowVolume = new ShadowVolume();

    // Set cursor to indicate that user can move the object with the mouse
#ifdef _WIN64
    SetClassLongPtr( m_hWnd, GCLP_HCURSOR, (LONG_PTR)LoadCursor( NULL, IDC_SIZEALL ) );
#else
    SetClassLong( m_hWnd, GCL_HCURSOR, HandleToLong( LoadCursor( NULL, IDC_SIZEALL ) ) );
#endif
    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: FrameMove()
// Desc: Called once per frame, the call is the entry point for animating
//       the scene.
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::FrameMove()
{
    // Setup the world spin matrix
    D3DXMatrixTranslation( &m_matTerrainMatrix, 0.0f, 0.0f, 0.0f );

    // Setup viewing postion from ArcBall
    m_matObjectMatrix = *m_ArcBall.GetRotationMatrix();
    D3DXMatrixMultiply( &m_matObjectMatrix, &m_matObjectMatrix, m_ArcBall.GetTranslationMatrix() );

    // Move the light
    FLOAT Lx =   5;
    FLOAT Ly =   5;
    FLOAT Lz =  -5;
    D3DLIGHT9 light;
    D3DUtil_InitLight( light, D3DLIGHT_POINT, Lx, Ly, Lz );
    light.Attenuation0 = 0.9f;
    light.Attenuation1 = 0.0f;
    m_pd3dDevice->SetLight( 0, &light );

    // Transform the light vector to be in object space
    D3DXVECTOR3 vLight;
    D3DXMATRIXA16 m;
    D3DXMatrixInverse( &m, NULL, &m_matObjectMatrix );
    vLight.x = Lx*m._11 + Ly*m._21 + Lz*m._31 + m._41;
    vLight.y = Lx*m._12 + Ly*m._22 + Lz*m._32 + m._42;
    vLight.z = Lx*m._13 + Ly*m._23 + Lz*m._33 + m._43;

    // Build the shadow volume
    m_pShadowVolume->Reset();
    m_pShadowVolume->BuildFromMesh( m_pAirplane->GetSysMemMesh(), vLight );

    return S_OK;
}




//-----------------------------------------------------------------------------
// Name: RenderShadow()
// Desc:
//-----------------------------------------------------------------------------
HRESULT CMyD3DApplication::RenderShadow()
{
    // Disable z-buffer writes (note: z-testing still occurs), and enable the
    // stencil-buffer
    m_pd3dDevice->SetRenderState( D3DRS_ZWRITEENABLE,  FALSE );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILENABLE, TRUE );

    // Dont bother with interpolating color
    m_pd3dDevice->SetRenderState( D3DRS_SHADEMODE,     D3DSHADE_FLAT );

    // Set up stencil compare fuction, reference value, and masks.
    // Stencil test passes if ((ref & mask) cmpfn (stencil & mask)) is true.
    // Note: since we set up the stencil-test to always pass, the STENCILFAIL
    // renderstate is really not needed.
    m_pd3dDevice->SetRenderState( D3DRS_STENCILFUNC,  D3DCMP_ALWAYS );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILZFAIL, D3DSTENCILOP_KEEP );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILFAIL,  D3DSTENCILOP_KEEP );

    // If ztest passes, inc/decrement stencil buffer value
    m_pd3dDevice->SetRenderState( D3DRS_STENCILREF,       0x1 );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILMASK,      0xffffffff );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILWRITEMASK, 0xffffffff );
    m_pd3dDevice->SetRenderState( D3DRS_STENCILPASS,      D3DSTENCILOP_INCR );

    // Make sure that no pixels get drawn to the frame buffer
    m_pd3dDevice->SetRenderState( D3DRS_ALPHABLENDENABLE, TRUE );
    m_pd3dDevice->SetRenderState( D3DRS_SRCBLEND,  D3DBLEND_ZERO );
    m_pd3dDevice->SetRenderState( D3DRS_DESTBLEND, D3DBLEND_ONE );