D3D与OpenGL常用API对译

D3D与OpenGL常用API对译

作为一个3D程序员, 我用了OpenGL两年多, 最近在搞一个项目, 从OpenGL转到D3D, 虽然工程外在的框架都封装得不错, 但想完全地从OpenGL转换到D3D, 看起来还是有难度的, 花了我两个星期的时间, 我终于转换过来了。
D3D与OpenGL的几点比较明显不同的地方:
(一)、正交投影时：OpenGL以屏幕左上角为(0,0), 而D3D却以屏幕中心为(0,0)
(二)、OpenGL使用右手坐标系， 而D3D使用左手坐标系
(三)、OpenGL使用旋转操作等转入的角度参数是 角度, 而D3D是 弧度，所以注意要PI * Angle / 180

下面我把具体地API对照关系列出来(不是很全，以后添加中.......)


1. 坐标变换
 pos = D3DXVECTOR3(0,2,-1.5);
 at  = D3DXVECTOR3(0,0,0);
 up  = D3DXVECTOR3(0,1,0);
 D3DXMatrixLookAtLH(&view,&pos,&at,&up);
 pd3dDevice->SetTransform(D3DTS_VIEW,&view);

2. 绘制
 pd3dDevice->SetRenderState(D3DRS_FILLMODE,D3DFILL_WIREFRAME);

    DrawPrimitive()
 DrawIndexedPrimitive()
 
 DrawPrimitiveUP()
 DrawIndexedPrimitiveUP()
3. 颜色

4. 片段测试

 (1) 深度测试
 g_pDevice->SetRenderState(D3DRS_ZENABLE, TRUE);           //glEnable(GL_DEPTH_TEST);  
 g_pDevice->SetRenderState(D3DRS_ZFUNC, D3DCMP_LESSEQUAL);    //glDepthFunc(GL_LEQUAL);
 //--------------------------------------------------------------------------------------------------------
 g_pDevice->SetRenderState(D3DRS_CULLMODE, D3DCULL_CCW);      //glEnable(GL_CULL_FACE);

 
 (2) Alpha测试
 //-------------------------------------------------------------------------------------------------------- 
 g_pDevice->SetRenderState(D3DRS_ALPHATESTENABLE, TRUE);                //glEnable(GL_ALPHA_TEST);
 g_pDevice->SetRenderState(D3DRS_ALPHAFUNC, D3DCMP_GREATER);    //glAlphaFunc(GL_GREATER, 0.1f);
 g_pDevice->SetRenderState(D3DRS_ALPHAREF, 0.1 * 255); //取值范围 0 ~ 255
 
 (3) 剪裁测试 (平面剪切)
 //--------------------------------------------------------------------------------------------------------
 // Enable clip plane for reflection map
 CMatrix44f pWorldViewProjIT=m_pWorldViewProj;
 //pWorldViewProjIT.Transpose();
 pWorldViewProjIT.Invert();   

 // Transform plane to clip-space
 float pClipSpacePlane[4];
 float pClipPlane[]= { 0, 0, 1, 0};   

 // Check if camera is below water surface, if so invert clip plane
 CVector3f pEye=(CVector3f)m_pCamera.GetPosition();
 if(-pEye.m_fZ<0.0)
 {
  pClipPlane[2]=-pClipPlane[2];
 }

 MatrixTransformPlane(pClipSpacePlane, pClipPlane, pWorldViewProjIT);

 // enable clip plane now
 g_pDevice->SetClipPlane(0, pClipSpacePlane);  
 g_pDevice->SetRenderState(D3DRS_CLIPPLANEENABLE, 1);
 
 
 
 (4) 模板测试
 //--------------------------------------------------------------------------------------------------------
 g_pDevice->SetRenderState(D3DRS_STENCILENABLE, TRUE);
    g_pDevice->SetRenderState(D3DRS_STENCILFUNC, 3DCMP_ALWAYS);
    g_pDevice->SetRenderState(D3DRS_STENCILREF, 0x1); //取值范围 0 ~ 255
   
    Device->SetRenderState(D3DRS_STENCILPASS,  D3DSTENCILOP_KEEP);
 
5. 纹理操作
 
 g_pDevice->SetSamplerState( 0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR);
   g_pDevice->SetSamplerState( 0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR);
   g_pDevice->SetSamplerState( 0, D3DSAMP_MIPFILTER, D3DTEXF_LINEAR);
   
 g_pDevice->SetSamplerState( 0, D3DSAMP_ADDRESSU, D3DTADDRESS_CLAMP);
  g_pDevice->SetSamplerState( 0, D3DSAMP_ADDRESSV, D3DTADDRESS_CLAMP);

6. 缓冲区操作
  
 (1) 颜色缓冲
 //--------------------------------------------------------------------------------------------------------
 g_pDevice->SetRenderState(D3DRS_COLORWRITEENABLE, D3DCOLORWRITEENABLE_ALPHA);
 g_pDevice->SetRenderState(D3DRS_COLORWRITEENABLE, 0x000000F);
 
 (2) 深度缓冲
 //--------------------------------------------------------------------------------------------------------
 g_pDevice->SetRenderState(D3DRS_ZENABLE, TRUE);           //glEnable(GL_DEPTH_TEST);
 g_pDevice->SetRenderState(D3DRS_ZWRITEENABLE, TRUE);        //glDepthMask(GL_TRUE);

 (3) 模板缓冲
 //--------------------------------------------------------------------------------------------------------
 
 (4) 渲染到纹理
 //--------------------------------------------------------------------------------------------------------
 // Render targets
 IDirect3DSurface9 *m_plD3DBackbufferSurf,
  *m_plD3DDepthStencilSurfAA,
  *m_plD3DDepthStencilSurf;

 CRenderTarget *m_pRTRefraction, *m_pRTReflection; //(自定义纹理类)

 //-----------------------------------------------------------------------------------

 // Get backbuffer
 g_pDevice->GetRenderTarget(0, &m_plD3DBackbufferSurf);
 
 // Get depthstencil
 g_pDevice->GetDepthStencilSurface(&m_plD3DDepthStencilSurfAA);
 

 // Restore previous states
 g_pDevice->SetRenderTarget(0, m_plD3DBackbufferSurf);
 g_pDevice->SetDepthStencilSurface(m_plD3DDepthStencilSurfAA);
 
 // (1)折射图--------------------------------------------------------------------------
 
 //下面的语句调用了 g_pDevice->CreateRenderTarget(iWidth, iHeight, (D3DFORMAT) iFormat, (D3DMULTISAMPLE_TYPE)iAASamples, 0, 0, &m_plD3Surf, 0));
 if(FAILED(m_pRTRefraction->Create(m_fWidth>>1, m_fHeight>>1, D3DFMT_A8R8G8B8)))
 {
  return APP_ERR_INITFAIL;
 }
 
 // Create depthstencil withouth multisampling
 g_pDevice->CreateDepthStencilSurface(m_fWidth, m_fHeight, D3DFMT_D24X8, (D3DMULTISAMPLE_TYPE)0, 0, 0, &m_plD3DDepthStencilSurf, 0);
 
 
 g_pDevice->SetRenderTarget(0, m_pRTReflection->GetSurface());
 
 g_pDevice->StretchRect(m_plD3DBackbufferSurf, 0, m_pRTRefraction->GetSurface(), 0, D3DTEXF_NONE);
 
 // (2)反射图-----------------------------------------------------------------------------------
 m_pRTReflection=new CRenderTarget;
 if(FAILED(m_pRTReflection->Create(m_fWidth>>2, m_fHeight>>2, D3DFMT_A8R8G8B8)))
 {
  return APP_ERR_INITFAIL;
 }
 
 g_pDevice->SetRenderTarget(0, m_pRTReflection->GetSurface());
 
 
 //-----------------------------------------------------------------------------------
 g_pDevice->SetRenderTarget(0, m_pRTReflection->GetSurface());
 g_pDevice->SetDepthStencilSurface(m_plD3DDepthStencilSurf);
 g_pDevice->Clear(0, 0, D3DCLEAR_TARGET|D3DCLEAR_ZBUFFER, D3DCOLOR_ARGB(255, 0, 0, 128), 1.0f, 0);  
 SetViewport(m_pRTReflection->GetWidth(), m_pRTReflection->GetHeight());
 //-----------------------------------------------------------------------------------
 
 D3DXSaveTextureToFile("imageTex.jpg",D3DXIFF_JPG,(IDirect3DTexture9*)m_pWavesBump->GetTexture(),NULL);
 
7. 混合操作
 g_pDevice->SetRenderState(D3DRS_ALPHABLENDENABLE, FALSE);    //glDisable(GL_BLEND);
 g_pDevice->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA);  //glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 g_pDevice->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA);
 

8. 灯光与材质
 g_pDevice->SetRenderState(D3DRS_LIGHTING, FALSE); //glDisable(GL_LIGHTING);
 
 D3DMATERIAL9 mtrl;
 mtrl.Ambient  = a;
 mtrl.Diffuse  = d;
 mtrl.Specular = s;
 mtrl.Emissive = e;
 mtrl.Power    = p;
 Device->SetMaterial(&mtrl);  //在设置纹理前设定
 //设置当前使用的纹理