关于DirectX 3D中画图问题

[Koo]

我想画个圆柱体
下面是显示代码：

bool Display(float timeDelta)
{
	if( Device )
	{
		static float angle  = (3.0f * D3DX_PI) / 2.0f;
		static float height = 5.0f;
		if( ::GetAsyncKeyState(VK_LEFT) & 0x8000f )
			angle -= 0.5f * timeDelta;

		if( ::GetAsyncKeyState(VK_RIGHT) & 0x8000f )
			angle += 0.5f * timeDelta;

		if( ::GetAsyncKeyState(VK_UP) & 0x8000f )
			height += 5.0f * timeDelta;
		if( ::GetAsyncKeyState(VK_DOWN) & 0x8000f )
			height -= 5.0f * timeDelta;		
		D3DXVECTOR3 position( cosf(angle) * 7.0f, height, sinf(angle) * 7.0f );
		D3DXVECTOR3 target(0.0f, 0.0f, 0.0f);
		D3DXVECTOR3 up(0.0f, 1.0f, 0.0f);
		D3DXMATRIX V;
		D3DXMatrixLookAtLH(&V, &position, &target, &up);
		Device->SetTransform(D3DTS_VIEW, &V);
		Device->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0x00000000, 1.0f, 0);
		Device->BeginScene();
		if((float)timeGetTime()-timenow<500)
		{
			for(int i = 0; i < 3; i++)
			{
				Device->SetMaterial(&Mtrls[i]);
				Device->SetTransform(D3DTS_WORLD, &Worlds[i]);
				Objects[i]->DrawSubset(0);
			}
		}
		else
		{
			//timenow=(float)timeGetTime();
			srand((unsigned)time(NULL));
			int r=rand()%6;
			D3DXMATRIX Rx,Ry,Rz,R,p;
			D3DXMatrixRotationX(&Rx,(float)atan(DirectionSet[r][1]/DirectionSet[r][2]));
			D3DXMatrixRotationX(&Ry,(float)atan(DirectionSet[r][2]/DirectionSet[r][0]));
			D3DXMatrixRotationX(&Rz,(float)atan(DirectionSet[r][0]/DirectionSet[r][1]));
			D3DXMatrixTranslation(&p,len[0]*DirectionSet[r][0]/2,len[0]*DirectionSet[r][1]/2,len[0]*DirectionSet[r][2]/2);
			p=Rx*Ry*Rz*R;
			Device->SetTransform(D3DTS_WORLD,&p);
			Device->SetMaterial(&Mtrls[0]);
			Objects[0]->DrawSubset(0);
		}
		Device->EndScene();
		Device->Present(0, 0, 0, 0);
	}
	return true;
}

我就一共定义了6个方向，我想让它0.5s以后随机转变方向

float len[3]={0.5f,2.0f,2.5f};
float CurrentDirection[3][3]={0.0f,0.0f,1.0f,0.0f,0.0f,1.0f,0.0f,0.0f,0.0f};
float DirectionSet[6][3]={1.0f,0.01f,0.01f,0.01f,0.01f,1.0f,-1.0f,0.01f,0.01f,0.01f,0.01f,-1.0f,0.01f,1.0f,0.01f,0.01f,-1.0f,0.01f};

但是0.5s以后它画出来的怎么是乱七八糟的东西，连圆柱都没有了？
这是一开始的0.5s内显示出来的东西

然后0.5s之后就显示这些乱七八糟的了。。。

[leizh007]

D3DXMatrixRotationX(&Rx,(float)atan(DirectionSet[r][1]/DirectionSet[r][2]));
            D3DXMatrixRotationY(&Ry,(float)atan(DirectionSet[r][2]/DirectionSet[r][0]));
            D3DXMatrixRotationZ(&Rz,(float)atan(DirectionSet[r][0]/DirectionSet[r][1]));
            D3DXMatrixTranslation(&R,len[0]*DirectionSet[r][0]/2,len[0]*DirectionSet[r][1]/2,len[0]*DirectionSet[r][2]/2);