Hello. I try to program rotation, that can be managed by mouse imput. Evereything works fine, when I roted only round the y-axis (horizontal mouse movement) or round the x-axis(vertical mouse movement. After I genereated each functionality for themself, I put them together so that I could rotated my face around two axis with one mousemove, but then the output is all nonsense. float laenge = m_KameraPosition.x*m_KameraPosition.x + m_KameraPosition.y*m_KameraPosition.y + m_KameraPosition.z*m_KameraPosition.z ; laenge = (float)sqrt(laenge); //This is the length of the vector, which represent the camera // this is rotation around y-axis m_KameraPosition.x = laenge * (float)sin(angleY); m_KameraPosition.z = laenge * (float)cos(angleY); // this is rotation aroun x-axis m_KameraPosition.y = laenge * (float)sin(angleX); m_KameraPosition.z = laenge * (float)cos(angleX); Can somebody eplain me, why these two part works fine when only one is used, but together my face disaper? Oh, I am porgramming in C++ and DirectX8 Taggi

look at these two lines:

quote:

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Original post by Tagamoga
m_KameraPosition.y = laenge * (float)sin(angleX);
m_KameraPosition.z = laenge * (float)cos(angleX);

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btw: you could leave out laenge because this sould be a direction vector I guess.

you''re assigning the y and z coordinates to pure x rotation of a base vector, the x coordinate is assigned to pure y rotation - this produces nonsense.

I''m assuming you want to do x rotation before y rotation like it''s done in common 3d games.

you could do the following things:

do x - rotation with a base vector like you did, then y - rotate the resulting point:
temppoint = point;

point.x = temppoint.x*cos(yAngle) + temppoint.z*sin(yAngle)
point.y = temppoint.y;
point.z = -temppoint.x*sin(yAngle) + temppoint.z*cos(yAngle)


a more advanced solution is to set up matrices for each rotation, multiply the matrices to concatenate rotations and transform tthe points which you want to rotate with the matrix.


GA