direct拾取的问题。
用Direct做了个用射线拾取的程序，当模型在场景中央（0，0，0）的时候可以精确的拾取，
可以模型移动位置后，就不那么精确了，而且摄像机移动后更加不精确了，几乎拾取不到了。
当移动模型或者摄像机的时候，射线所在的空间好像会向摄像机方向移动一些（摄像机位置：0，0，-100）
清高手们帮忙解决啊 谢谢。
[解决办法]
给你个例子吧，相机移动了，射线也要重新计算啊
IDirect3DDevice9* Device = 0; const int Width = 640;const int Height = 480;ID3DXMesh* Teapot = 0;ID3DXMesh* Sphere = 0;D3DXMATRIX World;d3d::BoundingSphere BSphere;//// Functions//d3d::Ray CalcPickingRay(int x, int y){ float px = 0.0f; float py = 0.0f; D3DVIEWPORT9 vp; Device->GetViewport(&vp); D3DXMATRIX proj; Device->GetTransform(D3DTS_PROJECTION, &proj); px = ((( 2.0f*x) / vp.Width) - 1.0f) / proj(0, 0); py = (((-2.0f*y) / vp.Height) + 1.0f) / proj(1, 1); d3d::Ray ray; ray._origin = D3DXVECTOR3(0.0f, 0.0f, 0.0f); ray._direction = D3DXVECTOR3(px, py, 1.0f); return ray;}void TransformRay(d3d::Ray* ray, D3DXMATRIX* T){ // transform the ray's origin, w = 1. D3DXVec3TransformCoord( &ray->_origin, &ray->_origin, T); // transform the ray's direction, w = 0. D3DXVec3TransformNormal( &ray->_direction, &ray->_direction, T); // normalize the direction D3DXVec3Normalize(&ray->_direction, &ray->_direction);}bool RaySphereIntTest(d3d::Ray* ray, d3d::BoundingSphere* sphere){ D3DXVECTOR3 v = ray->_origin - sphere->_center; float b = 2.0f * D3DXVec3Dot(&ray->_direction, &v); float c = D3DXVec3Dot(&v, &v) - (sphere->_radius * sphere->_radius); // find the discriminant float discriminant = (b * b) - (4.0f * c); // test for imaginary number if( discriminant < 0.0f ) return false; discriminant = sqrtf(discriminant); float s0 = (-b + discriminant) / 2.0f; float s1 = (-b - discriminant) / 2.0f; // if a solution is >= 0, then we intersected the sphere if( s0 >= 0.0f || s1 >= 0.0f ) return true; return false;}//// Framework functions//bool Setup(){ // // Create the teapot. // D3DXCreateTeapot(Device, &Teapot, 0); // // Compute the bounding sphere. // BYTE* v = 0; Teapot->LockVertexBuffer(0, (void**)&v); D3DXComputeBoundingSphere( (D3DXVECTOR3*)v, Teapot->GetNumVertices(), D3DXGetFVFVertexSize(Teapot->GetFVF()), &BSphere._center, &BSphere._radius); Teapot->UnlockVertexBuffer(); // // Build a sphere mesh that describes the teapot's bounding sphere. // D3DXCreateSphere(Device, BSphere._radius, 20, 20, &Sphere, 0); // // Set light. // D3DXVECTOR3 dir(0.707f, -0.0f, 0.707f); D3DXCOLOR col(1.0f, 1.0f, 1.0f, 1.0f); D3DLIGHT9 light = d3d::InitDirectionalLight(&dir, &col); Device->SetLight(0, &light); Device->LightEnable(0, true); Device->SetRenderState(D3DRS_NORMALIZENORMALS, true); Device->SetRenderState(D3DRS_SPECULARENABLE, false); // // Set view matrix. // D3DXVECTOR3 pos(0.0f, 0.0f, -10.0f); D3DXVECTOR3 target(0.0f, 0.0f, 0.0f); D3DXVECTOR3 up(0.0f, 1.0f, 0.0f); D3DXMATRIX V; D3DXMatrixLookAtLH(&V, &pos, &target, &up); Device->SetTransform(D3DTS_VIEW, &V); // // Set projection matrix. // D3DXMATRIX proj; D3DXMatrixPerspectiveFovLH( &proj, D3DX_PI * 0.25f, // 45 - degree (float)Width / (float)Height, 1.0f, 1000.0f); Device->SetTransform(D3DTS_PROJECTION, &proj); return true;}void Cleanup(){ d3d::Release<ID3DXMesh*>(Teapot); d3d::Release<ID3DXMesh*>(Sphere);}bool Display(float timeDelta){ if( Device ) { // // Update: Update Teapot. // static float r = 0.0f; static float v = 1.0f; static float angle = 0.0f; D3DXMatrixTranslation(&World, cosf(angle) * r, sinf(angle) * r, 10.0f); // transfrom the bounding sphere to match the teapots position in the // world. BSphere._center = D3DXVECTOR3(cosf(angle)*r, sinf(angle)*r, 10.0f); r += v * timeDelta; if( r >= 8.0f ) v = -v; // reverse direction if( r <= 0.0f ) v = -v; // reverse direction angle += 1.0f * D3DX_PI * timeDelta; if( angle >= D3DX_PI * 2.0f ) angle = 0.0f; // // Render // Device->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffffffff, 1.0f, 0); Device->BeginScene(); // Render the teapot. Device->SetTransform(D3DTS_WORLD, &World); Device->SetMaterial(&d3d::YELLOW_MTRL); Teapot->DrawSubset(0); // Render the bounding sphere with alpha blending so we can see // through it. Device->SetRenderState(D3DRS_ALPHABLENDENABLE, true); Device->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA); Device->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA); D3DMATERIAL9 blue = d3d::BLUE_MTRL; blue.Diffuse.a = 0.25f; // 25% opacity Device->SetMaterial(&blue); Sphere->DrawSubset(0); Device->SetRenderState(D3DRS_ALPHABLENDENABLE, false); Device->EndScene(); Device->Present(0, 0, 0, 0); } return true;}//// WndProc//LRESULT CALLBACK d3d::WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam){ switch( msg ) { case WM_DESTROY: ::PostQuitMessage(0); break; case WM_KEYDOWN: if( wParam == VK_ESCAPE ) ::DestroyWindow(hwnd); break; case WM_LBUTTONDOWN: // compute the ray in view space given the clicked screen point d3d::Ray ray = CalcPickingRay(LOWORD(lParam), HIWORD(lParam)); // transform the ray to world space D3DXMATRIX view; Device->GetTransform(D3DTS_VIEW, &view); D3DXMATRIX viewInverse; D3DXMatrixInverse(&viewInverse, 0, &view); TransformRay(&ray, &viewInverse); // test for a hit if( RaySphereIntTest(&ray, &BSphere) ) ::MessageBox(0, "Hit!", "HIT", 0); break; } return ::DefWindowProc(hwnd, msg, wParam, lParam);}//// WinMain//int WINAPI WinMain(HINSTANCE hinstance, HINSTANCE prevInstance, PSTR cmdLine, int showCmd){ if(!d3d::InitD3D(hinstance, Width, Height, true, D3DDEVTYPE_HAL, &Device)) { ::MessageBox(0, "InitD3D() - FAILED", 0, 0); return 0; } if(!Setup()) { ::MessageBox(0, "Setup() - FAILED", 0, 0); return 0; } d3d::EnterMsgLoop( Display ); Cleanup(); Device->Release(); return 0;}
[解决办法]
对阿，怀疑楼主的射线计算有问题，检查一下。能把你算射线的代码贴出来看看么？
[解决办法]
D3DXMatrixInverse(&inverse,0,matWorld);
世界矩阵就不要来掺和了。
ray->_direction经过view矩阵的反矩阵已经是世界坐标系了，你在巴世界矩阵反矩阵变化到了局部坐标系了，就不对了。
[解决办法]
POINT ptCursor; GetCursorPos( &ptCursor ); ScreenToClient( DXUTGetHWND(), &ptCursor ); // Compute the vector of the Pick ray in screen space D3DXVECTOR3 v; v.x = ( ( ( 2.0f * ptCursor.x ) / pd3dsdBackBuffer->Width ) - 1 ) / pmatProj->_11; v.y = -( ( ( 2.0f * ptCursor.y ) / pd3dsdBackBuffer->Height ) - 1 ) / pmatProj->_22; v.z = 1.0f; // Get the inverse view matrix const D3DXMATRIX matView = *g_Camera.GetViewMatrix(); const D3DXMATRIX matWorld = *g_Camera.GetWorldMatrix(); D3DXMATRIX mWorldView = matWorld * matView; D3DXMATRIX m; D3DXMatrixInverse( &m, NULL, &mWorldView ); // Transform the screen space Pick ray into 3D space vPickRayDir.x = v.x * m._11 + v.y * m._21 + v.z * m._31; vPickRayDir.y = v.x * m._12 + v.y * m._22 + v.z * m._32; vPickRayDir.z = v.x * m._13 + v.y * m._23 + v.z * m._33; vPickRayOrig.x = m._41; vPickRayOrig.y = m._42; vPickRayOrig.z = m._43;