acces PMatrix

Programming Questions

clankill3r

in Programming Questions • 26 days ago

I want to learn more about matrixes.

How can i get either the current PMatrix2D or PMatrix3D?

I know there is printMatrix() but i want the object itself.

Specially i want to experiment with multX and multY.

And why are there so many?

```
                 
```
// All the matrices required for camera and geometry transformations.
public PMatrix3D projection;
public PMatrix3D camera;
public PMatrix3D cameraInv;
public PMatrix3D modelview;
public PMatrix3D modelviewInv;
public PMatrix3D projmodelview;

             The code really lacks of comments. I'm guessing a projection get's first aplied and as last the camera.
            

             But what are cameraInv, modelbiew, modelviewInv and projmodelview good for?
            

             Hope someone can helps and explain a bit. 
            

Replies(3)

andres

the two important matrices are modelview and projection (which are applied in that order, i.e.: screen_position = projection * modelview * world_position). camera is simply contains the contribution of the camera() function to the modelview matrix, you could write:

modelview = after_camera * camera

where after_camera is the matrix that contains all the geometric transformations after setting the camera.

The other matrices are auxiliary matrices that are pre-calculated in order to avoid computing matrix inverses and multiplications redundantly:

cameraInv = inverse of camera

modelviewInv = inverse of modelview

projmodelview = projection * modelview

If you change camera or modelview manually, you should update the auxiliary matrices accordingly.

clankill3r

Re: acces PMatrix

23 days ago

Ok thanks.

Do you happen to know how i can acces them?

andres

Re: acces PMatrix

23 days ago

all these matrices are public, so you can access them simply by:

PGraphicsOpenGL pg = (PGraphicsOpenGL)g;
println(pg.modelview.print());

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