我选对了吗？

Posted 2023-02-22

【中文标题】我选对了吗？

【英文标题】：Am I doing Picking right?

【发布时间】：2011-04-21 17:47:14

【问题描述】：

所以我正在研究我的拣货功能。我已经阅读了几个教程并阅读了一些帖子，我已经到了这一点。但是还是不行。 我的代码有什么问题？

BOOL Directx::Picking(HWND hWnd, AnimatedMesh *entity)

    POINT pt;
    D3DVIEWPORT9 vp;
    D3DXMATRIX matWorld, matView, matProj;

    GetCursorPos(&pt);
    ScreenToClient(hWnd, &pt);
    d3ddev->GetTransform(D3DTS_PROJECTION, &matProj);
    d3ddev->GetViewport(&vp);
    d3ddev->GetTransform(D3DTS_WORLD, &matWorld);
    d3ddev->GetTransform(D3DTS_VIEW, &matView);

    // Use inverse of matrix
    D3DXVECTOR3 rayPos(pt.x, pt.y,0); // near-plane position
    D3DXVECTOR3 rayDir(pt.x, pt.x,1); // far-plane position
    D3DXVec3Unproject(&rayPos,&rayPos,&vp,&matProj,&matView,&matWorld);
    D3DXVec3Unproject(&rayDir,&rayDir,&vp,&matProj,&matView,&matWorld);
    rayDir -= rayPos; // make a direction from the 2 positions
    D3DXVec3Normalize(&rayDir,&rayDir);
    // Transform ray origin and direction by inv matrix

    BOOL hasHit;
    float distanceToCollision;

    if(FAILED(D3DXIntersect(entity->pDrawMesh, &rayPos, &rayDir, &hasHit, NULL, NULL, NULL, &distanceToCollision, NULL, NULL)))
    
        PostQuitMessage(0);
    ;

    if(hasHit!=0)
        PostQuitMessage(0);
    else
    
        s=rayPos;
    

    return hasHit;

【问题讨论】：

你想在屏幕中间挑选对象吗？ （从屏幕中心开始的射线

好吧，我想在屏幕上的任何地方挑选对象。

@Tiago 您想使用远程访问，以便访问我的笔记本电脑并查看发生了什么并查看整个项目？

if(hasHit!=0) PostQuitMessage(0); HasHit != 0 表示射线击中了一个物体，那么为什么要关闭程序呢？

刚刚到现在。

【参考方案1】：

试试这个：

BOOL Directx::Picking(HWND hWnd, AnimatedMesh *entity)

    POINT pt;
    D3DVIEWPORT9 vp;
    D3DXMATRIX matProj, matView;

    GetCursorPos(&pt);
    ScreenToClient(hWnd, &pt);

    float w = (float)backBufferWidth;
    float h = (float)backBufferHeight;

    d3ddev->GetTransform(D3DTS_VIEW, &matView);
    d3ddev->GetTransform(D3DTS_PROJECTION, &matProj);
    d3ddev->GetViewport(&vp);

    //Transform cursor position to view space
    float x = (2.0f*pt.x/w - 1.0f) / matProj(0,0);
    float y = (-2.0f*pt.y/h + 1.0f) / matProj(1,1);


    D3DXVECTOR3 rayOrigin(0.0f, 0.0f,0.0f); // near-plane position
    D3DXVECTOR3 rayDir(x, y, 1.0f); // far-plane position

    D3DXMATRIX matInvView;

    D3DXMatrixInverse(&matInvView, 0, &matView);

    D3DXVECTOR3 rayOriginW, rayDirW;

    // Transform picking ray to world space.
    D3DXVec3TransformCoord(&rayOriginW, &rayOrigin, &invView);
    D3DXVec3TransformNormal(&rayDirW, &rayDdir, &invView);
    D3DXVec3Normalize(&rayDirW, &rayDirW);

    BOOL hasHit;
    float distanceToCollision;

    if(FAILED(D3DXIntersect(entity->pDrawMesh, &rayOriginW, &rayDirW, &hasHit, NULL, NULL, NULL, &distanceToCollision, NULL, NULL)))
    
        PostQuitMessage(0);
    ;

    s=rayPos;

    return hasHit;