急！dx3d 的问题

dengguoyu

  我在dx3d9中运行Tutorials3。这是一个简单的正三角形沿Y轴旋转，我把它改为按z轴旋转，但是正三角形旋转到不在0度或180度的时候会发生变形。我怎么也不能使它在旋转时保持原形，有谁知道为什么吗？
  请各位高人指点,小生这厢有礼了！ [em24]

strong

那是因为观察点的原因，将D3DXVECTOR3 vEyePt( 0.0f, 3.0f,-5.0f );
换成D3DXVECTOR3 vEyePt( 0.0f, 0.0f,-5.0f );就能满足你的要求了，

sea_bug

看你是如何进行旋转的，如果只是视角旋转，那么要注意距离，如果只是世界坐标轴的旋转，那应该就很容易了。

dengguoyu

[em4] [em4] [em4]
我就是八十点改为在z轴上观察的，初始状态如下:
g_matWorld( 1, 0, 0, 0,
                0, 1, 0, 0,
                0, 0, 1, 0,
                0, 0, 0, 1 );

g_matview( 1, 0, 0, 0,
                0, 1, 0, 0,
                0, 0, 1, 0,
                0, 0, 0, 1 );
g_EyePt( 0.0f, 0.0f, -10.0f );
g_LookatPt( 0.0f, 0.0f, 1.0f );
g_vUpVec( 0.0f, 1.0f, 0.0f );
g_FieldOfView( D3DX_PI / 4 );
g_AspectRatio( 1.0f );
g_NearClip( 0.0f );
g_FarClip( 100.0f );

{ -1.0f,-1.0f, 0.0f, 0xffff0000, },
{  1.0f,-1.0f, 0.0f, 0xffff0000, },
{  0.0f, 1.0f, 0.0f, 0xffff0000, },

这时是正三角形没错，我在SetupMatrices里改了一下，大概如下：

case VK_NEXT: //得到绕z轴旋转的矩阵
  D3DXMatrixRotationZ( &matTemp, -g_RotationDelta );

//设置世界矩阵
g_pd3dDevice->SetTransform( D3DTS_WORLD, &g_matWorld );

//设置视点矩阵，我试过旋转世界矩阵或视点矩阵都是一样的结果：
//只要不是在0度获180度，三角形旋转后看起来不再是正三角形了
D3DXMATRIXA16 matView;
D3DXMatrixMultiply( &matView, &g_matView, &matTemp );
g_matView = matView;
D3DXMatrixLookAtLH( &matTemp, &g_vEyePt, &g_vLookatPt, &g_vUpVec );
D3DXMatrixMultiply( &matView, &g_matView, &matTemp );

g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView );

//投影矩阵
D3DXMATRIXA16 matProj;
D3DXMatrixPerspectiveFovLH( &matProj, g_FieldOfView, g_AspectRatio, g_NearClip, g_FarClip );
g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj );

请各位高人看看 ！

dengguoyu

没人指点吗？

dengguoyu

我顶，顶到解决为止

sea_bug

//-----------------------------------------------------------------------------
// Name: SetupMatrices()
// Desc: Sets up the world, view, and projection transform matrices.
//-----------------------------------------------------------------------------
VOID SetupMatrices()
{
    // For our world matrix, we will just rotate the object about the y-axis.
    D3DXMATRIXA16 matWorld;

    // Set up the rotation matrix to generate 1 full rotation (2*PI radians)
    // every 1000 ms. To avoid the loss of precision inherent in very high
    // floating point numbers, the system time is modulated by the rotation
    // period before conversion to a radian angle.
    UINT  iTime  = timeGetTime() % 1000;
    FLOAT fAngle = iTime * (2.0f * D3DX_PI) / 1000.0f;
    D3DXMatrixRotationY( &matWorld, fAngle );
    g_pd3dDevice->SetTransform( D3DTS_WORLD, &matWorld );

    // Set up our view matrix. A view matrix can be defined given an eye point,
    // a point to lookat, and a direction for which way is up. Here, we set the
    // eye five units back along the z-axis and up three units, look at the
    // origin, and define "up" to be in the y-direction.
    D3DXVECTOR3 vEyePt( 0.0f, 3.0f,-5.0f );
    D3DXVECTOR3 vLookatPt( 0.0f, 0.0f, 0.0f );
    D3DXVECTOR3 vUpVec( 0.0f, 1.0f, 0.0f );
    D3DXMATRIXA16 matView;
    D3DXMatrixLookAtLH( &matView, &vEyePt, &vLookatPt, &vUpVec );
    g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView );

    // For the projection matrix, we set up a perspective transform (which
    // transforms geometry from 3D view space to 2D viewport space, with
    // a perspective divide making objects smaller in the distance). To build
    // a perpsective transform, we need the field of view (1/4 pi is common),
    // the aspect ratio, and the near and far clipping planes (which define at
    // what distances geometry should be no longer be rendered).
    D3DXMATRIXA16 matProj;
    D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI/4, 1.0f, 1.0f, 100.0f );
    g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj );
}

这里是DX9 SDK的Tut03_Matrices例子中的代码片断，其中：

    UINT  iTime  = timeGetTime() % 1000;
    FLOAT fAngle = iTime * (2.0f * D3DX_PI) / 1000.0f;
    D3DXMatrixRotationY( &matWorld, fAngle );
    g_pd3dDevice->SetTransform( D3DTS_WORLD, &matWorld );

这里用来做世界旋转的处理，把D3DXMatrixRotationY()改成D3DXMatrixRotationZ()看看是否可行。

dengguoyu

就是把D3DXMatrixRotationY()改成D3DXMatrixRotationZ()然后把
D3DXVECTOR3 vEyePt( 0.0f, 3.0f,-5.0f );
改为在z轴上便于观察
D3DXVECTOR3 vEyePt( 0.0f, 0.0f,-5.0f );
只要不是在0度或180度，三角形旋转后看起来不再是正三角形了，
请sea_bug兄帮忙看看
其实是backbuffer的width和height不是一比一的缘故（窗口模式可以改为1:1但全屏好像不能为1:1），能给出避免的方案吗？ [em7]
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