hi i have some problems to correctly rotate a cube to the other.

i have one cube that i can move and i need the other cube to rotate in his direction when its moving

when run program, the cube rotates some in the dircection but when i go behind or under it changes direction.

i think it has somthing to do whit the direction of the cube ,or the angle or the rotation direction

this is the code dat i update:

translationform1 =XMVectorSet (xaxis1, 0.0f, zaxis1,0.0f);
cube1transform = XMVectorSet(3.0f, 0.0f, 4.5f, 0.0f);
cube2transform = XMVectorSet(-5.0f , 0.0f, 4.5f, 0.0f);
directioncube = cube1transform - cube2transform;

cubetranslation1 = D3DXVECTOR3(xaxis1, 0.0f, zaxis1);
cubelocation1 = D3DXVECTOR3(3.0f, 0.0f, 4.5f);
cube2position = D3DXVECTOR3(-5.0f, 0.0f, 4.5f);


cubeposition = cube1transform + translationform1;
cubepos1 = cubelocation1 + cubetranslation1;

cubeoldpos = cubepos1 - cubetranslation1;

*//direction2=0.0f,0.0f,1.0f)

direction2 = direction2; // i also tried cubeoldposition-cube2position "to get the new direction whit eache update"..
direction1 = cubepos1 - cube2position;

D3DXVec3Normalize(&direction2Norm, &direction2);
D3DXVec3Normalize(&direction1Norm, &direction1);
directioncubeNorm = XMVector3Normalize(directioncube);


renderrotate = D3DXVec3Dot(&direction1Norm, &direction2Norm);
dot = renderrotate;
renderrotate = (acos(renderrotate));


if (dot < 0)
renderrotate *=-1;

else
renderrotate *=1;




rotation = XMMatrixRotationY(renderrotate);

translation1 = XMMatrixTranslationFromVector(cubeposition);
cubeworld1 = translation1;

forwardcube = cube2transform + directioncubeNorm ;


translation2 = XMMatrixTranslation(-5.0f,0.0f,4.5f);

cubeworld2 = rotation*translation2;

You have vectors called translation, transform, location and position, all of which sound like pretty much the same thing. Then there are variables that contain "cube1" in the name and variables that contain "cube2" in the name, but then there is "cubeposition", which I don't know which cube it's referring to. This makes your code very hard to follow. If we were dealing with working code, I could try to look at what you are computing and deduce what things mean from there, but with non-working code it's just hopeless.

Can you either use better names or provide some comments explaining what you are trying to do?

ok i hope this explains som things

translationform1 =XMVectorSet (xaxis1, 0.0f, zaxis1,0.0f); //the amount that cube1 has to move increses or decreses when i use the arrow keys;
cube1transform = XMVectorSet(3.0f, 0.0f, 4.5f, 0.0f); //is the start postion of the first cub that i can move
cube2transform = XMVectorSet(-5.0f , 0.0f, 4.5f, 0.0f);// is the start position of the second move and stays put


cubetranslation1 = D3DXVECTOR3(xaxis1, 0.0f, zaxis1); //does the same as translationform1;
cubelocation1 = D3DXVECTOR3(3.0f, 0.0f, 4.5f);//is again the start position of the first cube;
cube2position = D3DXVECTOR3(-5.0f, 0.0f, 4.5f);// is again the start position of the second cube;
// i use these to calculate the dot product XMVector3Dot returns a vector and i need a float;

cubeposition = cube1transform + translationform1; // calculates the new position of cube1 when cube 1 is moved

cubepos1 = cubelocation1 + cubetranslation1; // does same as cubeposition but whit the D3XVECTOR3

cubeoldpos = cubepos1 - cubetranslation1; // caluclates the old postion of cube1;

direction2 = direction2; // direction2 = (0.0f,0.0f,1.0f) i also tried here direction2= cubeoldpos -cube2position to calulate the direction that he is now facing;
direction1 = cubepos1 - cube2position;

D3DXVec3Normalize(&direction2Norm, &direction2);
D3DXVec3Normalize(&direction1Norm, &direction1); // normalize direction1 and direction2



renderrotate = D3DXVec3Dot(&direction1Norm, &direction2Norm);// the dot porduct of direction1 and 2
dot = renderrotate;
renderrotate = (acos(renderrotate)); // calculate the acos of dot


if (dot < 0)
renderrotate *=-1;

else
renderrotate *=1; //this i us to get the direction to rotate but dont know if this is corect




rotation = XMMatrixRotationY(renderrotate); //rotation to cube 1

translation1 = XMMatrixTranslationFromVector(cubeposition); // traslation of the first cube using the xmvextors;
cubeworld1 = translation1;




translation2 = XMMatrixTranslation(-5.0f,0.0f,4.5f);

cubeworld2 = rotation*translation2; //the rotation and translation of second cube;

1.) Why is nearly all declared or computed twice?

2.) Why are variable names chosen so that they are not distinguishable from others?

3.) Why are variable names for semantically the same thing so different as for cubepos1 and cube2position?

4.) Why the redundant computation here (2nd line)?

cubepos1 = cubelocation1 + cubetranslation1

cubeoldpos = cubepos1 - cubetranslation1

5.) The dot-product gives a negative result if the angle between the 2 arguments is greater than 90°. The acos gives values in range [0,pi]. This means that your computation makes no difference between rotation to the left and rotation to the right, and it has discontinuities at +90° and -90°.

In general: Clean up your code, drop duplicates, bring calculations in a meaningful order, choose meaningful names, choose similarly looking name schemes for semantically equal variables. This makes things easier to read for you and anyone you show the code, and it makes debugging easier. Not doing so is part of the problem, really! Mistakes have much less chance to hide in a clearly structured code.

Then read about the cross-product as a possibility to distinguish whether to rotate to the left or to the right: Use the sign of the cross-product to mirror the angle.

Hello. when you get your code fixed up, you will want to look up atan2 function on google.

used like this.

v3 unitfacingdirection(0,0,1);//facing the z direction this is the meshes exported facing

v3 targetpos;//the object you want to face at position

v3 totargetdirection = targetpos - unitfacingdirection;

totargetdirection.normalize();

double angle = atan2(totargetdirection.x, totargetdirection.z);//if your terrain is on the x , z plane.