3D游戏程序设计入门中模板缓存的问题

O湛狼O

                Device->BeginScene();

                RenderScene();

                RenderMirror();       

                Device->EndScene();
                Device-&gtresent(0, 0, 0, 0);
        }
        return true;
}

void RenderScene()
{
        // draw teapot
        Device->SetMaterial(&TeapotMtrl);
        Device->SetTexture(0, 0);
        D3DXMATRIX W;
        D3DXMatrixTranslation(&W,
                TeapotPosition.x,
                TeapotPosition.y,
                TeapotPosition.z);

        Device->SetTransform(D3DTS_WORLD, &W);
        Teapot->DrawSubset(0);

        D3DXMATRIX I;
        D3DXMatrixIdentity(&I);
        Device->SetTransform(D3DTS_WORLD, &I);

        Device->SetStreamSource(0, VB, 0, sizeof(Vertex));
        Device->SetFVF(Vertex::FVF);

        // draw the floor
        Device->SetMaterial(&FloorMtrl);
        Device->SetTexture(0, FloorTex);
        Device->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 2);

        // draw the walls
        Device->SetMaterial(&WallMtrl);
        Device->SetTexture(0, WallTex);
        Device->DrawPrimitive(D3DPT_TRIANGLELIST, 6, 4);

        // draw the mirror
        Device->SetMaterial(&MirrorMtrl);
        Device->SetTexture(0, MirrorTex);
        Device->DrawPrimitive(D3DPT_TRIANGLELIST, 18, 2);
}       

void RenderMirror()
{
        //
        // Draw Mirror quad to stencil buffer ONLY.  In this way
        // only the stencil bits that correspond to the mirror will
        // be on.  Therefore, the reflected teapot can only be rendered
        // where the stencil bits are turned on, and thus on the mirror
        // only.
        //

    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, true);
    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);

        D3DXMATRIX I;
        D3DXMatrixIdentity(&I);
        Device->SetTransform(D3DTS_WORLD, &I);

        Device->DrawPrimitive(D3DPT_TRIANGLELIST, 18, 2);

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

        // only draw reflected teapot to the pixels where the mirror
        // was drawn to.
        Device->SetRenderState(D3DRS_STENCILFUNC,  D3DCMP_EQUAL);
    Device->SetRenderState(D3DRS_STENCILPASS,  D3DSTENCILOP_KEEP);

        // 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);

        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);
        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);
}


为什么我把镜子的值设置为0的话，镜子前的茶壶就不会挡住镜子里的茶壶？设置为1的话就可以呢？
Device->SetRenderState(D3DRS_STENCILREF,       0x1);就是这句。最后哪里改为0x0;
模板缓存不是只是限制了渲染范围吗？就是下面这两种情况！

O湛狼O

求助啊。

O湛狼O

再顶。。。

snhun

Device->SetRenderState(D3DRS_STENCILFUNC,D3DCMP_EQUAL);

看似这一句很关键。
我没学过D3D，不懂。

O湛狼O

额。

onemoo

SetRenderState( D3DRS_STENCILREF, 0x1 ) 设置的是参考值

SetRenderState( D3DRS_STENCILPASS， D3DSTENCILOP_REPLACE ) 如果测试通过就用参考值替换模板缓冲中的值
你还替换成0，说明模板缓存内容未被改变，还是0

SetRenderState( D3DRS_STENCILFUNC, D3DCMP_EQUAL ) 所有模板中等于参考值的地方都渲染
结合你上面的设置，这等于是让模板失去了标记功能，什么也不做，模型全被渲染

O湛狼O

是啊。但是镜子中的就算设置为1还是会渲染镜子范围内的，设置为0也是会渲染，两个都一样。为什么会出现那种效果？

O湛狼O

上面两图都是镜子范围内的。也就是说都会渲染啦。效果却不一样！

O湛狼O

求助，谁能解释一下啊。是不是我什么地方理解错了？

O湛狼O

深度缓存清楚为1.0后，墙、镜子、原茶壶不是可以认为是在同一深度1.0了吗？怎么会出现原茶壶挡住反射茶壶、而镜子却没有挡住反射茶壶这种情况呢？既然在同一深度，就应该一起挡住、或者一起被挡啊。

难道这个问题又要不了了之？就没有牛人肯指点一下吗？