javascript - Quadratic Bezier Curve with inner Triangle -


recently building javascript module add convenience functions draw quadratic bezier curve. function have source point, target point , control point , create svg path this: 

<path id="active" d="m"+sourcepoint+" q "+controlpoint+" "+ targetpoint+" " fill="orange"  fill-opacity="0.8" stroke="steelblue" stroke-width="2px" cursor="move">

the point have mention is, control point change dynamically, when change have figure this:

note

i downloaded image this link.

this regular way draw quadratic curve outer triangle "imagine triangle p0,p1,p2 points".i don't know if there ways calculate b point on curve?

my goal draw quadratic curve inner triangle p1 on curve this:

enter image description here

is there way draw kind of quadratic curve or calculate b point on first picture?

formula find coordinates of point b @ needed value t on quadratic bezier curve (apply formula each coordinates x , y)

b(t) = p0 * (1-t)^2 + 2 * p1 * t * (1-t) + p2 * t^2

geometric subdivision approach:

let's q0 divides p0-p1 segment in t/(1-t) proportion

|p0q0|/|q0p1| = t/(1-t)

let's q1 divides p1-p2 segment in (1-t)/t proportion

|p1q1|/|q1p2| = (1-t)/t

b divides q0-q1 segment in t/(1-t) proportion

|q0b|/|bq1| = t/(1-t)

if want build curve through points p0 (start), c (somewhere in middle), , p2 (end), choose value of t point c, apply formula given, , find unknown control point p1. example, if t=1/2

c(1/2)=p0/4+2p1/4+p2/4 p1 = (4c - p0 - p2) / 2

Comments

Post a Comment

Popular posts from this blog

javascript - Using jquery append to add option values into a select element not working -

i'm looking dynamically populate select element names of items stored array. for reason it's not working , i'm not sure why. html: <div class="col-md-4 col-md-offset-4"> <select class="select1"> </select> , <select class="select2"> </select> </div> note i'm using bootstrap layout. here's jquery i'm using try , populate ".select1" jquery: select: function() { $.each(state.greens, function(index, value) { $(".select1").append("<option value =' " + index + " '>" + state.greens[index].name + "</option>"); }); } note function 'select' stored within object called 'display'. state.greens name of array i'm trying access. so @ end of html page call display.select(); call function. no error messages showing in console. also, saw question: appending
Read more

Android soft keyboard reverts to default keyboard on orientation change -

i'm building android soft keyboard , can't seem fix bug - have arabic , qwerty keyboard , when rotate device on qwerty keyboard (or arabic shift), it's if program has "restarted" , becomes arabic keyboard without shift. the onsaveinstancestate(bundle savedinstancestate) not work because application not extend activity inputmethodservice . i put following in android manifest android:configchanges="keyboard|keyboardhidden|orientation" android:windowsoftinputmode="stateunchanged|adjustresize"> i tried using @override public void onconfigurationchanged(configuration newconfig) { super.onconfigurationchanged(newconfig); log.i(mydebug, "config changed " + currentkeyboard.equals(qwerty)); } however, currentkeyboard.equals(qwerty)) results false , made sure true before orientation change. any appreciated. i think applications fault. if application restarting on orientation change
Read more

Rendering JButton to get the JCheckBox behavior in a JTable by using images does not update my table -

i rendering jbutton image on simulate jcheckbox behavior. why don't let jtable render jcheckbox? because need bigger checkboxes , there's no way can resize them (as far know). so, have own table cell renderer , editor. both renders jbutton , checkbox images on them. trying change image checked image unchecked image (or vice versa) , update cell value (boolean true or false). however, reason, getcelleditorvalue() not update table. so, release mouse, value goes original one. any appreciated! lot! public class tableexample extends jframe { jscrollpane pane; jpanel panel; jtable table; object[][] data; mytablemodel tm; renderer buttoncolumn; public tableexample(object[][] data) throws ioexception { string[] columns = {"column#1", "column#2", "column#3", "column#4", "column#5", "column#6"}; this.data = data; this.setpreferredsize(new dimension(700, 500));
Read more