平面陰隱其實就是將物體“壓扁”到某一平面進行繪制。原理類似于投影
而對于一個三維物體來說，當(dāng)多個部分投影到平面上時，會產(chǎn)生疊加效果，導(dǎo)致某一部位顏色較深，而此時我們可以通過模版緩存來防止二次融合，從而避免這類現(xiàn)象的產(chǎn)生。
Device->Clear(0,0,D3DCLEAR_TARGET|D3DCLEAR_ZBUFFER|D3DCLEAR_STENCIL,0xfff0000,1.0,0);
Device->SetRenderState(D3DRS_STENCILENABLE,true);
Device->SetRenderState(D3DRS_STENCILFUNC,D3DCMP_EQUAL);
Device->SetRenderState(D3DRS_STENCILREF,0x0);
Device->SetRenderState(D3DRS_STENCILMASK,0xffffffff);
Device->SetRenderState(D3DRS_STENCILWRITEMASK,0xffffffff);
Device->SetRenderState(D3DRS_STENCILZFAIL,D3DSTENCILOP_KEEP);
Device->SetRenderState(D3DRS_STENCILFAIL,D3DSTENCILOP_KEEP);
Device->SetRenderState(D3DRS_STENCILPASS,D3DSTENCILOP_INCR);
首先開啟模版,將測試規(guī)則設(shè)置為"相等",模版參考設(shè)置為0,失敗時候不更改,成功的時候增加1.
由于我們已經(jīng)將模版緩存清0 ,于是,當(dāng)?shù)谝淮螌懭肽０娴臅r候,測試總是成功的,模版值加1.而當(dāng)?shù)诙螌懭氲臅r候,模版值與模版參考值不相等,測試便會失敗,從而阻止了再次寫入緩存.
Device->SetRenderState(D3DRS_ALPHABLENDENABLE,true);
Device->SetRenderState(D3DRS_SCRBLEND,D3DBLEND_SCRALPHA);
Device->SetRenderState(D3DRS_DESTBLEND,D3DBLEND_INVSRCAPHA);
Device->SetRenderState(D3DRS_ZENABLE,false);
//使用D3DXMatrixShadow(&S,&linghtDirection,&groundplane);
//S為最后輸出的矩陣,然后是光線方向,然后是要繪制陰影的平面
//繪制
//最后做收尾工作
Device->SetRenderState(D3DRS_ZENABLE,true);
Device->SetRenderState(D3DRS_ALPHABLENDENABLE,false);
Device->SetRenderState(D3DRS_STENCILENABLE,false);