Jump to content
  • Advertisement
Sign in to follow this  
ibr_ozdemir

DirectionToRotation doesnt work

This topic is 4059 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

hi i'm using following code block for Directions to Rotation (x,y,z) but it doesnt work correctly, whats the problem?
procedure DirectionToRotation(Direction,Up,Right:TD3DVector; var Rotation:TD3DVector);
var
  s,c:single;
begin
  s:=-Right.z;
  c:=sqrt(Right.x*Right.x+Right.y*Right.y);
  Rotation.y:=-RadToDeg(ArcTan2(s,c));
  if c>UBEpsilon then
  begin
    Rotation.x:=-RadToDeg(ArcTan2(Up.z,Direction.z));
    Rotation.z:=-RadToDeg(ArcTan2(Right.y,Right.x));
  end
  else
  begin
    Rotation.x:=0;
    Rotation.z:=-RadToDeg(-Sign(s)ArcTan2(-Direction.y,Up.y));
  end;
end;


Share this post


Link to post
Share on other sites
Advertisement
It looks like you're trying to perform a matrix-to-Euler-angle conversion. Unfortunately, 'it doesn't work' doesn't give us much to go on (I suppose we could just proof your code, but that's usually not a very effective way of helping someone).

There are a number of ways in which such a conversion can 'not work' (or appear not to work):

1. Difference in input and output due to floating-point imprecision

2. Difference in input and output due to aliasing of Euler-angle triples

3. Improper handling of corner cases

4. Wrong axis order (e.g. xyz instead of xzy)

5. Confusion regarding conventions (such as matrix 'majorness' or vector orientation)

The math library linked in my signature includes code for matrix-Euler conversions that supports all possible orders (xyz, xyx, zxy, etc.). Similar code is available elsewhere online as well (check the Wikipedia article on Euler angles).

Share this post


Link to post
Share on other sites
i'm filling my matrix like this
(in xyz order)

var
m:TD3DMatrix;
begin
D3DXMatrixRotationX(matris,-DegToRad(Rotation.X));
D3DXMatrixRotationY(m,-DegToRad(Rotation.Y));
D3DXMatrixMultiply(matris,matris,m);
D3DXMatrixRotationZ(m,-DegToRad(Rotation.Z));
D3DXMatrixMultiply(matris,matris,m);
end;



i'm using left hand coordinate system

and all examples which i found with google "matrix to euler" doesnt work correctly they go nut when angles over 90 degre or 270 or 180, when rotation be x=42 y=67 z=85 its working just like i want.

these are some methods which i found
(you dont have to read all of these many of them look like eachother)

sy:=-Direction.x;
cy:=sqrt(1-(sy*sy));
yr:=ArcTan2(sy,cy);
Rotation.y:=RadToDeg(yr);
if (sy<>1)and(sy<>-1) then
begin
Rotation.x:=RadToDeg(arctan2(Direction.y/cy,Direction.z/cy));
Rotation.z:=RadToDeg(arctan2(Up.x/cy,Right.x/cy));
end
else
begin
Rotation.x:=RadToDeg(arctan2(-Up.z,Up.y));
Rotation.z:=RadToDeg(arctan2(0,1));
end;



x:=arcsin(Direction.y);
cosX:=Cos(x);
if cosX < 0.005 then
begin
z:=0;
y:=Sign(-Up.x)*ArcCos(Right.x);
end
else
begin
z:=Sign(Right.y)*ArcCos(Up.y/cosX);
y:=Sign(Direction.x)*ArcCos(Direction.z/cosX);
if (Sign(Up.y)=-1) and (z=0) then
begin
z:=z+pi;
y:=y+pi;
end;
end;
Rotation:=D3DXVector3(RadToDeg(x),RadToDeg(y),RadToDeg(z));



y:=-ArcSin(Direction.x);
C:=cos(Y);
if (abs(C)>0.0005) then
begin
X:=ArcTan2( Direction.y / C, Direction.z / C );
Z:=ArcTan2( Up.x / C, Right.x / C );
end
else
begin
X:=0;
Z:=ArcTan2(-Right.y,Up.y );
end;
Rotation:=D3DXVector3(RadToDeg(x),RadToDeg(y),RadToDeg(z));



angle_y:=ArcSin(Right.z);
c:=cos(angle_y);
if abs(C)>0.005 then
begin
angle_x:=ArcTan2(-Up.z/c,Direction.z/c);
angle_z:=ArcTan2(-Right.y/c,Right.x/c);
end
else
begin
angle_x:=0;
angle_z:=ArcTan2(Up.y,Up.x);
end;
angle_x:=RadToDeg(angle_x);
angle_y:=RadToDeg(angle_y);
angle_z:=RadToDeg(angle_z);
Rotation:=D3DXVector3(angle_x,angle_y,angle_z);



if Up.x>0.998 then
begin
heading:=ArcTan2(Right.z,Direction.z);
attitude:=Pi/2;
bank:=0;
end
else
if (Up.x<-0.998) then
begin
heading:=arctan2(Right.z,Direction.z);
attitude:=-PI/2;
bank:=0;
end
else
begin
heading:=arctan2(-Direction.x,Right.x);
bank:=arctan2(-Up.z,Up.y);
attitude:=arcsin(Up.x);
end;
Rotation:=D3DXVector3(RadToDeg(bank),RadToDeg(heading),RadToDeg(attitude));



also these codes send by happy coders :) i mean all of these codes are working just fine for message owners, maybe they are not filling matrix like me or they are using different systems, i dont know

thanks everyone

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!