How to get project matrix

[realm-2003]

hi, all,

I want to get the projection matrix from maya. The project matrix is used to project 3D to 2D, similar to gluLookat and gluPerspective in openGL, I know, using xform mel command can get information about the transformation matrix, but not projection matrix.

Is there any API or any other ways to read/get the current project matrix in maya scene? Basically, I want to get this projection matrix out, then I can set this information back into OPENGL by glMultMatrix...

any suggestions or comments will be appreciated.
Thanks.

realm

[odimann]

hi,
this should be very easy.
first get the active View from M3dView, then get a dagPath to the actual camera. With MFnCamera you can extract the matrix with projectonMatrix()

M3dView view = M3dView::active3dView();
MDagPath camPath;
view.getCamera(camPath);
MFnCamera camFn(camPath);
MFloatMatrix fmatrix = camFn.projectionMatrix();

I did not test the code, but it should run.

good luck

[realm-2003]

Thanks for your help. your code does work.

But I have another problem:

I want to extract the eye, projection_center, upDirection information from maya and apply it to openGL environment via gluPerspective,gluLookAt.

I follow your method and use the following code.

MPoint eye = camFn.eyePoint(MSpace::kWorld);
MPoint center = camFn.centerOfInterestPoint(MSpace::kWorld);
MVector up =camFn.upDirection(MSpace::kWorld);
double aspect=camFn.aspectRatio();
double near_clip= camFn.nearClippingPlane();
double far_clip = camFn.farClippingPlane();
double fovy = camFn.verticalFieldOfView();

But it turns out the position information(such as eye position) is not correct. kind of confused. Did I specify wrong argument(kWorld) to function call?

Thanks again.

[odimann]

I think your code should be right and the returned position should be correct. when do you call this functions in your plugin? Are you sure that you extract the information from the camera you want?
I dont know why your code shouldn't run...sorry

[realm-2003]

odimann, Thanks.

Actually, your code really work and it return some values which should be correct. But my problem concerns the difference between the maya camera and openGL camera. I wan to composite two images, one is rendered from maya, the other is rendered by a special-purpose openGL render program(I only can control the camera etc).

maya rendered a 3D model(let's say A), and openGL program render another 3D model(let's say . These two models(A and are perfectly matched in 3D..... So, I need to read the perspetive camera position from maya, then set back to the openGL program by gluPespective and gluLookAt. In this way, if these two programs rendered the two models using the same camera, then the rendered images should be perfectly matched.

If I directly set the values got from maya camera back to opengl functions.... it doesn't work..
It is' true that maya camera is much more complex than opengl's..

[gileo]

Hi!

I surfed the following link some days ago,
perhaps it is related to your problem?

http://www.cs.bris.ac.uk/~pupilli/MayaProjection.html

Bye
Gileo