关于 mirror的wenti

calm0067

请问各位高人，我在做stencilmirror时，为何前端的teapot没有遮挡住在墙壁中反射的倒影！让我很困惑！请指教

奇怪的东西

先画镜子里的壶再画外面的?

calm0067

        Device->Clear(0, 0, D3DCLEAR_STENCIL, 0xff000000, 1.0f, 0L);
    Device->SetRenderState(D3DRS_STENCILENABLE,    true);
    Device->SetRenderState(D3DRS_STENCILFUNC,      D3DCMP_ALWAYS);
    Device->SetRenderState(D3DRS_STENCILREF,       0x1);
    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_REPLACE);

        // disable writes to the depth and back buffers
    Device->SetRenderState(D3DRS_ZWRITEENABLE, false);
    Device->SetRenderState(D3DRS_ALPHABLENDENABLE, false);
    Device->SetRenderState(D3DRS_SRCBLEND,  D3DBLEND_ZERO);
    Device->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_ONE);

    // draw the mirror to the stencil buffer
        Device->SetStreamSource(0, VB, 0, sizeof(Vertex));
        Device->SetFVF(Vertex::FVF);
        /*
        Device->SetMaterial(&MirrorMtrl);
        Device->SetTexture(0, MirrorTex);
        */
        Device->SetMaterial(&WallMtrl);
        Device->SetTexture(0, WallTex);
        D3DXMATRIX I;
        D3DXMatrixIdentity(&I);
        Device->SetTransform(D3DTS_WORLD, &I);
        Device->DrawPrimitive(D3DPT_TRIANGLELIST, 6, 4);

        // re-enable depth writes
        Device->SetRenderState( D3DRS_ZWRITEENABLE, true );

        // only draw reflected teapot to the pixels where the mirror
        // was drawn to.
问题在这里，如果用下面的渲染方式这没有这种问题
        Device->SetRenderState(D3DRS_STENCILFUNC, D3DCMP_EQUAL);
        Device->SetRenderState(D3DRS_STENCILPASS, D3DSTENCILOP_KEEP);
而用下面三句，则会造成上面图中所表示的样子，请问高手这其中的原因在哪
//        Device->SetRenderState(D3DRS_STENCILFUNC,  D3DCMP_GREATER);
//        Device->SetRenderState(D3DRS_STENCILPASS,  D3DSTENCILOP_INVERT);
//        Device->SetRenderState(D3DRS_STENCILFAIL,  D3DSTENCILOP_REPLACE);

        // position reflection
        D3DXMATRIX W, T, R;
        D3DXPLANE plane(0.0f, 0.0f, 1.0f, 0.0f); // xy plane
        D3DXMatrixReflect(&R, &plane);

        D3DXMatrixTranslation(&T,
                TeapotPosition.x,
                TeapotPosition.y,
                TeapotPosition.z);

        D3DXMatrixMultiply(&W, &T, &R);

        // clear depth buffer and blend the reflected teapot with the mirror

        Device->Clear(0, 0, D3DCLEAR_ZBUFFER, 0, 1.0f, 0);

        Device->SetRenderState(D3DRS_SRCBLEND,  D3DBLEND_DESTCOLOR);
        Device->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_ZERO);

        // Finally, draw the reflected teapot
        Device->SetTransform(D3DTS_WORLD, &W);
        TeapotMtrl = d3d::GREEN_MTRL;
        Device->SetMaterial(&TeapotMtrl);
        Device->SetTexture(0, 0);

//        Device->SetRenderState(D3DRS_CULLMODE, D3DCULL_CW);
        Teapot->DrawSubset(0);
       
        // Restore render states.
        Device->SetRenderState(D3DRS_ALPHABLENDENABLE, false);
        Device->SetRenderState( D3DRS_STENCILENABLE, false);
        Device->SetRenderState(D3DRS_CULLMODE, D3DCULL_CCW);

czlc

Device->DrawPrimitive(D3DPT_TRIANGLELIST, 6, 4);
执行这里的时候出了两边的墙为0x1外，其它object在模板缓冲中的值都为0x0.包括茶壶本身。
Device->SetRenderState(D3DRS_STENCILFUNC,  D3DCMP_GREATER);
表明ref > value即0x1 > value。所以茶壶本身也会通过测试，所以它也会和自己的倒影相混合，进而进行渲染。