MathsOntologie may help a bit, too: There is a "TrianglePlein" object which properties are linked to each other by setters; for example, if you change the length of one side, the area will change at the same time.
I found many useful methods of the "point" object, for example the area of a triangle is one of these methods... Alain On Thu, Mar 21, 2013 at 9:09 AM, S Krish <[email protected]>wrote: > There are two ways to approach this problem: > > * Spatial > > * Vector > > *Spatial:* > > As per the pharo by example pdf, you can create a custom TriangleMorph ( > they have a cross ). Add the behavior that you mention to the > TriangleMorphWithAttributes that holds the plain triangle morph. So on > change to the attributes it will modify the triangle. > > There are challenges to using angle / other geometric approaches in the > above, but simple and probably a day's effort. Good for Kid's / early > school graphics > > I am not sure but many other contributions, half way done are there > which do have some works in this line of thought including one on > Kinesthetics with balls that have a gravity like pull etc.. which are quite > good enough. > > *Vector: > * > CAD/ Dr. Geo approach: Use a line that makes a Triangle. Perhaps may need > to add a surface for color fill also. Typical in CAD is to create a > polyline that makes an arbitrary line collection with several points as > input. If its closed you can treat it as an arbitrary polygon with > recognition of the bounded surface for color fill. > > You will then need to do something similar to above to have custom change > shape on attribute changes. > > The offside here is it will be time consuming and will need to use > standard vector formulae's for accuracy with sin / cos transformation as > you deal with angles. > > If you want this, better be sure about the whole requirement, you might > reinvent the Dr. Geo work.. better to study works done in say VW for .dxf > reading / display / CAD package completely once before embarking on this > route. > > > > > On Wed, Mar 20, 2013 at 3:33 PM, sminni <[email protected]> wrote: > >> Hi >> >> I have a small project (a real requirement) and I want a little guidance >> to >> do it (myself) - >> pl. assume I am new to pharo though I can navigate the IDE & have a >> background in O-O development. >> >> 1. Draw a triangle with draggable handles on points >> 2. The sides length and angles will be displayed (in editable fields) >> 3. We can lock any of the sides / angles >> 4. If the side / angle is edited then an action can be initiated to >> recomplete the triangle by redrawing the side clicked next >> >> Thanks >> Sanjay >> >> >> >> ----- >> --- >> Regards, Sanjay >> -- >> View this message in context: >> http://forum.world.st/new-learning-project-tiangle-with-draggable-points-on-a-screen-tp4677486.html >> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. >> >> >
