   vector maths
  Hi to all,    Can anyone help me fix this problem.i am working on collision avoidance for ai vehicle .For that i have to know future position of my aivehicle in a x,z plane. y axis is for rotation only.Example:myaicar position & rotation isposition = "200.081 1 -612.843 ";rotation = "0 1 0 87.0896"; //87.0896 is angle   //x axis rotation is 0   //y axis rotation is 1   //z axis rotation is 0myaicar target position is //this is the path my aicar travellingpath1 = "400 -612.843 1";path2 = "400 -900.784 1";path3 = "200 -900.784 1";path4 = "200 -612.843 1";i tried it   float speed = 10;D3DXMATRIX rot;   D3DXVECTOR3 vecf(1,0,0);D3DXVECTOR3 speedvector;float X_POSITION =200.081f,Y_POSITION = 1, Z_POSITION =-612.843f;D3DXMatrixRotationY(&rot,87.0896f);D3DXVec3TransformNormal(&vecf,&vecf,&rot);speedvector=vecf*speed;X_POSITION+=speedvector.x;Z_POSITION+=speedvector.z; cout<<X_POSITION<<endl<<Y_POSITION<<endl<<Z_POSITION; result is fine206.4911-605.168but i tried to path3 from path2 rotation in y axis rotation is 182.201result is410.081-900.729but i wanted a result like this4001-910Please someone guide me achieve thisThanks in advance  ---Rajesh---   
  i solved the above issue .Thank you for the guys tried to help me   