Panning and zooming a component, Computer Graphics

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.

Posted Date: 3/14/2013 1:18:16 AM | Location : United States







Related Discussions:- Panning and zooming a component, Assignment Help, Ask Question on Panning and zooming a component, Get Answer, Expert's Help, Panning and zooming a component Discussions

Write discussion on Panning and zooming a component
Your posts are moderated
Related Questions
?What is Computer Resolution?

Determine the transformation matrix for: a) Cavalier projection with θ=45 0 , and b) Cabinet projection with θ=30 0    c) Draw the projection of unit cube for all transfor

Gourand shading and Phong shading a. Gourand shading OR Intensity interpolation scheme We will discuss such scheme in further section of Gourand shading OR Intensity in

Subdivision Algorithm - Visible Surface Detection 1) Initialize the area to be the whole screen. 2) Create a PVPL regarding an area, sorted on z min as the smallest z coor

Associative Links: it is a link that is completely independent of the exact structure of the information. For illustration we have links depends on the meaning of various informat

examples and equation of reflection

Local Illumination Model - Polygon Rendering In this only light that is directly reflected by a light source through a surface to our eyes is observed. No explanation is taken

Polygon Filling Algorithm - Raster Graphics and Clipping In several graphics displays, this becomes essential to differentiate between different regions by filling them along

Consider the line segment AB in 3-Dimentional parallel to the z-axis along with end points A (- 5,4,2) and also B (5,-6,18). Carry out a perspective projection upon the X=0 plane;

Can you tell which main components (hardware and software) are needed for computer graphics? Besides the computer, some special devices and software may be needed especially fo