Sign in to follow this  

Problem with Translation and Rotation in DirectX

This topic is 2043 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

I have made a tank model, now I am trying to make the tank move FORWARD and then stop and rotate around itself to change its position then move forward again.

When I rotate the tank and change the Z axis to move it forward, it doesn't move FORWARD, it move in another position.

The code is similar to the following:

D3DXMATRIX matRot;
D3DXMATRIX matCenter;
D3DXMATRIX matScale;

D3DXMatrixTranslation(&matCenter, 0.0f, 0.0f, 0.0f); // *** Rotation point ***
D3DXMatrixTranslation(&matPos, tankPosX, -240.0f, tankPosZ);
D3DXMatrixRotationYawPitchRoll(&matRot, D3DXToRadian(tankRotX), D3DXToRadian(0.0f), D3DXToRadian(0.0f));
D3DXMatrixScaling(&matScale, 1.0f, 1.0f, 1.0f);

d3ddev->SetTransform(D3DTS_WORLD, &(matScale * matCenter * matRot * matPos)); Edited by Medo3337

Share this post


Link to post
Share on other sites
are you sure your adding to the tanks forward correctly? i mean, if you want the tank to move forward (+z in tank space), and only add to the tanks z axis, it will move towards the +z in world space, no matter which way your tank is facing or how you rotated it. working with vectors for these kinds of things work well. so, when you rotate the tank, you should also rotate the tanks "forward" vector, then just add that forward vector to the tanks final position, something like this:

[left][background=rgb(250, 251, 252)]D3DXMATRIX matRot;[/background][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]D3DXMATRIX matCenter;[/background][/size][/font][/color][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]D3DXMATRIX matScale;[/background][/size][/font][/color][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]D3DXMATRIX [/background][/size][/font][/color][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]posZUnitVec;[/background][/size][/font][/color][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]D3DXVECTOR3 vecTankForward;[/background][/size][/font][/color][/left]

[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]D3DXMatrixRotationYawPitchRoll(&[/background][/size][/font][/color][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]matRot[/background][/size][/font][/color][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)], D3DXToRadian(tankRotX), D3DXToRadian(0.0f), D3DXToRadian(0.0f));[/background][/size][/font][/color][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]D3DXMatrixTranslation(&posZUnitVec, 0.0f, 0.0f, 1.0f); // matrix holding position of vector pointing to positive z[/background][/size][/font][/color][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]D3DXMATRIX m = posZUinitVec * matRot;[/background][/size][/font][/color][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]vecTankForward = D3DXVECTOR3([/background][/size][/font][/color][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]m[/background][/size][/font][/color][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]._41,[/background][/size][/font][/color][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]m[/background][/size][/font][/color][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]._42,[/background][/size][/font][/color][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]m[/background][/size][/font][/color][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]._43); // Get vector from the matrix[/background][/size][/font][/color][/left]

// move the tank forward (speed is the speed you want to move the tank every time this function is called)
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]tankPosX += speed * vecTankForward.x; [/background][/size][/font][/color][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]tankPosZ += speed * vecTankForward.z;[/background][/size][/font][/color][/left]

[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]D3DXMatrixTranslation(&matCenter, 0.0f, 0.0f, 0.0f); // *** Rotation point ***[/background][/size][/font][/color][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]D3DXMatrixTranslation(&matPos, tankPosX, -240.0f, tankPosZ);[/background][/size][/font][/color][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]D3DXMatrixScaling(&matScale, 1.0f, 1.0f, 1.0f);[/background][/size][/font][/color][/left]

[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)]d3ddev->SetTransform(D3DTS_WORLD, &(matScale * matCenter * matRot * matPos)); [/background][/size][/font][/color][/left] Edited by iedoc

Share this post


Link to post
Share on other sites
@iedoc:That works perfectly! there is still one problem, If I am trying to apply that on airstrike as well, when the airstrike LOOK UP, it will NOT move up, I mean I want to update the rotation on any Axis (X, Y or Z) and the model still move FORWARD, if the model front is pointed up, the model should go up on Y axis while moving forward, so the airstrike can take off and start flying.

Share this post


Link to post
Share on other sites
not sure if you've tried this, but you will also have to add the y component of the "forward" vector to the things position. I only added the x and z above. so you need to do this:


[left][background=rgb(250, 251, 252)][size=3]tankPosX += speed * vecTankForward.x;[/size][/background][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)][size=3]tankPosY += speed * vecTankForward.y;[/size][/background][/size][/font][/color][/left]
[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)][size=3]tankPosZ += speed * vecTankForward.z;[/size][/background][/size][/font][/color][/left]

[left][color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif][size=3][background=rgb(250, 251, 252)][size=3]D3DXMatrixTranslation(&matPos, tankPosX, [/size][size=3]tankPosY[/size][size=3], tankPosZ);[/size][/background][/size][/font][/color][/left] Edited by iedoc

Share this post


Link to post
Share on other sites
Yeah, I tried this before I posted, but it makes the mesh move up even if its not pointed up since you increase the Y axis even if the mesh is moving straight on the ground!

So I tried to check for rotation on Yaw before changing the position on Y axis:

tankPosX += speed * vecTankForward.x;
if (rotYaw != 1.0f)
tankPosY += speed * vecTankForward.y;
tankPosZ += speed * vecTankForward.z;

D3DXMatrixTranslation(&matPos, tankPosX, tankPosY, tankPosZ);

However, I am not very sure if this will work fine on any mesh, airstrike, tank, human, helicopter, etc... Edited by Medo3337

Share this post


Link to post
Share on other sites

This topic is 2043 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.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this