Panning and zooming a component, Computer Graphics

Assignment Help:

Panning and zooming Components (such as your Polybounce or Animation) is simply a matter of reFrameing the world window. To pan right or left horizontally, one shifts it in the positive or negative x direction, respectively. To pan up or down vertically one shifts it in the positive or negative y direction. If factor is the fraction of the world window that you want to pan, these can be implemented as:

// Horiz. pan --- Pan left moves world window left void Polybounce::panH(double factor)
{
reFrame(world()+Point2(w_width()*factor,0));
}
// Vert. pan --- Pan up moves world window down
void Polybounce::panV(double factor)
{
reFrame(world()+Point2(0,w_height()*factor));
}

To zoom in or out, one needs to resize the world window either smaller or larger, respectively, without changing the center of the window. You can do this by ?rst translating the center of the window to the origin, then scaling the window (using scalar multiplication of RealRects), then translating it back to its original center.

This still only takes a few lines of code. If scale is the scaling factor:

// Zoom
void Polybounce::zoom(double scale)
{
Point2 center( (world().left()+world().right())/2,
(world().bottom()+world().top())/2 );
// translate to origin
reFrame(world()-center);
// scale by getZoom
reFrame(world()*Point2(scale,scale));
// translate back
reFrame(world()+center);
}

To add panning and zooming to your Polybounce without pan and zoom sliders,you can simply add keyboard events for these which just pan by a ?xed fragment,1/4 of the window, say, and zoom by ?xed scaling factors, perhaps 1/2 for zoom in and 2 for zoom out. These could be added to the Polybounce class, but they will need to be passed from the Display class anyway, so there is no reason to not just call the pan and zoom functions directly from Display's keyboard event handler.


Related Discussions:- Panning and zooming a component

Transform from the world to viewing coordinate system, To transform from th...

To transform from the world coordinate system to viewing coordinate system you need to perform the following operations.  a)  Translate the viewing coordinate origin to the worl

Process of objects in raster display and random display, Explain process of...

Explain process of displaying objects in raster display and random display. Draw block diagrams of the architecture of both the display systems.

B splines, What is uniform rational splines

What is uniform rational splines

Poser - software to generate computer animations, Poser - software to gener...

Poser - software to generate computer animations Poser: Poser through Curious Labs Creates 3-dimentaional complex models which you can view from any angle, distance o

Interlaced gif, Interlaced GIF: The conventional which is non-interlaced G...

Interlaced GIF: The conventional which is non-interlaced GIF graphic downloads one line of pixels at one time from top to bottom and browsers display all lines of the image as it

What is orthographic oblique projection, What is orthographic oblique proje...

What is orthographic oblique projection?  When the direction of the projection is not normal (not perpendicular) to the view plane then the projection is called as oblique proj

What is persistence, Persistence: How long they continue to emit light (...

Persistence: How long they continue to emit light (that is, have excited electrons returning to the ground state) after the CRT beam is removed. Persistence is defined as the ti

List of 3-d animation software, List of 3-D Animation Software Here is ...

List of 3-D Animation Software Here is a short list of several 3-D animation software are - Softimage ( Microsoft) -  Alias/Wavefront ( SGI) -  3D studia MAX (Autodesk

Advantages of computer aided design, Advantages of Computer aided design  ...

Advantages of Computer aided design  -   It is simpler to modify drawings  -   A library of parts can be kept  -   Ability to do automatic costings -   Ability to mod

Vecgen, explain vecgen algoritham

explain vecgen algoritham

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd