Re: Graphic transforms

Tech-Archive recommends: Speed Up your PC by fixing your registry

> This is the idea. One thinks of rotation as happening 'naturally' about a
> certain point of an object......
>...
> Thus the full transform function is as follows:
>
> transform = T(-x-rotate_dx,-y-rotate_dy) S(scale_x,scale_y) R(r)
> T(x+rotate_dx, y+rotate_dy) T(dx, Tdy)
>
> applied from left to right, with:
>
> T = translate
> R = rotate
> S = scale
>
> And there you have it! The trick is moving it to the wrod origin before
> scaling and rotating to ease the computations, and to scale before
rotating
> since scaling can be performed on two axes.
>
> Is that what you were asking? : )
>
I believe you just killed the newsgroup with this quantum mechanics like
explanation. :-)
A lot of people here will need counseling here I guess. :-)

But you are right in your explanation.

But you forget that every object has another rotation called orientation.
;-)
First is the rotation and translation regarding of your parent starting
coordinate.
Second the orientation rotation on it's own axis (assuming that you do not
have an offset)

I am happy that GDI+ has DirectX and OpenGL like transforming functionality.
I missed that in GDI a lot.

I noticed that in the Windows vista they have created a very simple DirectX
engine usable in .NET, so I guess that 3D visualization will become much
more easy to implement.
But nevertheless, translation/rotation/scaling is confusing for any newbie
trying it.


.

Relevant Pages

  • Re: Object rotation
    ... > need to translate back to the origin first, then rotate, then translate to ... For example rotations are ALWAYS around an axis so if you ... then moves on the new x axis after the Z rotation. ...
    (microsoft.public.win32.programmer.directx.managed)
  • Re: centr of rotation/centering
    ... I'm doing a simple molecular viewer. ... I'd like to rotate it, translate it, and center on any atom, using ... rotation, the rotation center is the old rotation center. ... ensure the order is translate then rotate and the effect ...
    (comp.graphics.api.opengl)
  • Re: translation and rotation in Euclidean space
    ... In the second place a single rotation only requires a 2x2 matrix. ... do and wish to rotate and translate a scene it is helpful if you process ... a 2d rank tensor, say Lij, a vector is a 1st rank tensor say Xi and ...
    (sci.physics.relativity)
  • centr of rotation/centering
    ... I'm doing a simple molecular viewer. ... I'd like to rotate it, translate it, and center on any atom, using ... glGetDoublev GL_MODELVIEW_MATRIX $mvmatrix ... rotation, the rotation center is the old rotation center. ...
    (comp.graphics.api.opengl)
  • Re: Graphics2D rotation
    ... the top layer should be ... redrawn in its next step of rotation. ... // then rotate ... // then translate back ...
    (comp.lang.java.programmer)