Theory on rotating with billboards....
Author
Hey, im trying to create a billboard, but havent been able to get it working.
Like what i tried doing was find the angles from the billboard to the camera point.
eg x -axis, y axis z axis
like i worked the angles like this
xAxis=getbearing(bz,by,cz,cy)
yAcis=getbearing(bx,bz,cx,cz)
etc
get bearing was just a function i made to work out the angle between 2 points on a graph.
bx etc is for billboard and c etc is for camera point
when i ran this code it worked sometimes but if you got the camera 2 close to it, it would flip over and look a little bit silly.
Any ideas on how to do it properly?
Thanks
simply use the inverted camera-matrix
like this:
D3DXMATRIX mCamera;
D3DXMATRIX mTransform;
D3DXVECTOR3 vPosition; // the position vektor
g_pDirect3DDevice->GetTransform(D3DTS_VIEW,&mCamera);
D3DXMatrixInvert(&mTransform,&mCamera);
mTransform._m41 = vPosition.x;
mTransform._m42 = vPosition.y;
mTransform._m43 = vPosition.z;
g_pDirect3DDevice->SetTransform(D3DTS_WORLD,&mTransform);
// drawing goes here
like this:
D3DXMATRIX mCamera;
D3DXMATRIX mTransform;
D3DXVECTOR3 vPosition; // the position vektor
g_pDirect3DDevice->GetTransform(D3DTS_VIEW,&mCamera);
D3DXMatrixInvert(&mTransform,&mCamera);
mTransform._m41 = vPosition.x;
mTransform._m42 = vPosition.y;
mTransform._m43 = vPosition.z;
g_pDirect3DDevice->SetTransform(D3DTS_WORLD,&mTransform);
// drawing goes here
How would you use the inverted camera matrix to rotate only about the Y axis?
pan narrans | My Website | Study + Hard Work + Loud Profanity = Good Code
pan narrans | My Website | Study + Hard Work + Loud Profanity = Good Code
Author
float GetBearing(float a, float b, float a2, float b2) { float offA= abs(a-a2); float offB= abs(b-b2); float answer; if (a2>a && b2<b) answer= atan(offB/offA); if (a2<=a && b2>b) answer= atan(offA/offB)+(D3DX_PI/2); if (a2<a && b2<=b) answer= atan(offB/offA)+D3DX_PI; if (a2>=a && b2<b) answer= atan(offA/offB)+(3*D3DX_PI/2); return answer; }ill try your suggestions
and i don''t know of any traditional matrix solution...
Why not try to get the view matrix, and then extract the Y rotation out of it? THe above tutorial shows you how, IIRC!
.lick
.lick
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement