D3 force layout with CSS positioning - svg

I'm placing circles on a map corresponding to GPS coordinates. Each circle is contained within an svg container which is placed on the page using CSS top and left properties. In my implementation, these containers often sit atop one another.
I am trying to implement collision detection and/or add a slight negative charge to these containers so that overlaps cause containers to distance themselves from one another.
Thus far, my tests with force layouts have either resulted in no change, or resulted in an error ('cannot set property index of null' or 'cannot set property x of null'). It's apparent that I'm doing something wrong but I have been unable to identify a path to resolution from the articles I've read online.
Any ideas on how I can stop the containers from sitting atop one another?
var self = this;
var data = [{lat: 127, lon: 36, name: 'a', radius: 9},{lat:127, lon: 36, name: 'b', radius: 9}];
// Position SVG containers correctly
var latLngToPx = function(d) {
var temp = new google.maps.LatLng(d.lat, d.lon);
temp = self.map.projection.fromLatLngToDivPixel(temp);
d.x = temp.x;
d.y = temp.y;
return d3.select(this)
.style('left', d.x + 'px')
.style('top', d.y + 'px');
};
var collide = function(node) {
var r = node.radius + 16,
nx1 = node.x - r,
nx2 = node.x + r,
ny1 = node.y - r,
ny2 = node.y + r;
return function(quad, x1, y1, x2, y2) {
if (quad.point && (quad.point !== node)) {
var x = node.x - quad.point.x,
y = node.y - quad.point.y,
l = Math.sqrt(x * x + y * y),
r = node.radius + quad.point.radius;
if (l < r) {
l = (l - r) / l * 0.5;
node.x -= x *= l;
node.y -= y *= l;
quad.point.x += x;
quad.point.y += y;
}
}
return x1 > nx2 || x2 < nx1 || y1 > ny2 || y2 < ny1;
};
}
var svgBind = d3.select(settings[type].layer).selectAll('svg')
.data(data, function(d){ return d.name; })
.each(latLngToPx);
var svg = svgBind.enter().append('svg')
.each(latLngToPx)
// svg[0] contains the svg elements
var nodes = svg[0];
var force = d3.layout.force()
.nodes(nodes)
.charge(-100)
.start();
force.on('tick', function(){
var q = d3.geom.quadtree(nodes),
i = 0,
n = nodes.length;
while (++i < n) {
q.visit(collide(nodes[i]));
}
svg
.style('left', function(d){ return (d.x - lm.config.offset) + 'px';})
.style('top', function(d){ return (d.y - lm.config.offset) + 'px';});
});
var circ = svg.append('circle')
.attr('r', settings[type].r)
.attr('cx',10)
.attr('cy',10)

You shouldn't need to do the collision detection yourself -- the force layout should take care of that for you. Here are the basic steps you need to take.
To each data element that represents a circle, add x and y members that contain their current (screen) coordinates. This is what the force layout will operate on.
Pass the array of these elements to the force layout as nodes. There's no need to set links to start with, although you might want to do so later to control the placement of nodes with respect to each other.
Start the force layout.
For each tick, redraw the elements at the appropriate position.
Tweak the parameters of the force layout to your liking.
You are doing most of this already, I'm just mentioning it again to clarify. The code would look something like this.
function latLngToPx(d) {
var temp = new google.maps.LatLng(d.lat, d.lon);
temp = self.map.projection.fromLatLngToDivPixel(temp);
d.x = temp.x;
d.y = temp.y;
};
data.forEach(function(d) { latLngToPx(d); });
var nodes = d3.select("body").selectAll("svg").data(data).enter().append("svg");
var force = d3.layout.force().nodes(data);
force.on("tick", function() {
nodes.style('left', function(d){ return (d.x - lm.config.offset) + 'px';})
.style('top', function(d){ return (d.y - lm.config.offset) + 'px';});
});

Related

How can I understand the following SVG code?

I have code from a web site, and it looks like it should be simple, but too simple for SVG. How can I determine if this is truly SVG, and what it does? I am especially interested in what looks like nested & and dots[.], then split, map.
Snippet:
// the shape of the dragon, converted from a SVG image
'! ((&(&*$($,&.)/-.0,4%3"7$;(#/EAA<?:<9;;88573729/7,6(8&;'.split("").map(function(a,i) {
shape[i] = a.charCodeAt(0) - 32;
});
Full code:
//7 Dragons
//Rauri
// full source for entry into js1k dragons: http://js1k.com/2014-dragons/demo/1837
// thanks to simon for grunt help and sean for inspiration help
// js1k shim
var a = document.getElementsByTagName('canvas')[0];
var b = document.body;
var d = function(e){ return function(){ e.parentNode.removeChild(e); }; }(a);
// unprefix some popular vendor prefixed things (but stick to their original name)
var AudioContext =
window.AudioContext ||
window.webkitAudioContext;
var requestAnimationFrame =
window.requestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(f){ setTimeout(f, 1000/30); };
// stretch canvas to screen size (once, wont onresize!)
a.style.width = (a.width = innerWidth - 0) + 'px';
a.style.height = (a.height = innerHeight - 0) + 'px';
var c = a.getContext('2d');
// end shim
var sw = a.width,
sh = a.height,
M = Math,
Mc = M.cos,
Ms = M.sin,
ran = M.random,
pfloat = 0,
pi = M.PI,
dragons = [],
shape = [],
loop = function() {
a.width = sw; // clear screen
for ( j = 0; j < 7; j++) {
if ( !dragons[j] ) dragons[j] = dragon(j); // create dragons initially
dragons[j]();
}
pfloat++;
requestAnimationFrame(loop);
},
dragon = function(index) {
var scale = 0.1 + index * index / 49,
gx = ran() * sw / scale,
gy = sh / scale,
lim = 300, // this gets inlined, no good!
speed = 3 + ran() * 5,
direction = pi, //0, //ran() * pi * 2, //ran(0,TAU),
direction1 = direction,
spine = [];
return function() {
// check if dragon flies off screen
if (gx < -lim || gx > sw / scale + lim || gy < -lim || gy > sh / scale + lim) {
// flip them around
var dx = sw / scale / 2 - gx,
dy = sh / scale / 2 - gy;
direction = direction1 = M.atan(dx/dy) + (dy < 0 ? pi : 0);
} else {
direction1 += ran() * .1 - .05;
direction -= (direction - direction1) * .1;
}
// move the dragon forwards
gx += Ms(direction) * speed;
gy += Mc(direction) * speed;
// calculate a spine - a chain of points
// the first point in the array follows a floating position: gx,gy
// the rest of the chain of points following each other in turn
for (i=0; i < 70; i++) {
if (i) {
if (!pfloat) spine[i] = {x: gx, y: gy}
var p = spine[i - 1],
dx = spine[i].x - p.x,
dy = spine[i].y - p.y,
d = M.sqrt(dx * dx + dy * dy),
perpendicular = M.atan(dy/dx) + pi / 2 + (dx < 0 ? pi : 0);
// make each point chase the previous, but never get too close
if (d > 4) {
var mod = .5;
} else if (d > 2){
mod = (d - 2) / 4;
} else {
mod = 0;
}
spine[i].x -= dx * mod;
spine[i].y -= dy * mod;
// perpendicular is used to map the coordinates on to the spine
spine[i].px = Mc(perpendicular);
spine[i].py = Ms(perpendicular);
if (i == 20) { // average point in the middle of the wings so the wings remain symmetrical
var wingPerpendicular = perpendicular;
}
} else {
// i is 0 - first point in spine
spine[i] = {x: gx, y: gy, px: 0, py: 0};
}
}
// map the dragon to the spine
// the x co-ordinates of each point of the dragon shape are honoured
// the y co-ordinates of each point of the dragon are mapped to the spine
c.moveTo(spine[0].x,spine[0].y)
for (i=0; i < 154; i+=2) { // shape.length * 2 - it's symmetrical, so draw up one side and back down the other
if (i < 77 ) { // shape.length
// draw the one half from nose to tail
var index = i; // even index is x, odd (index + 1) is y of each coordinate
var L = 1;
} else {
// draw the other half from tail back to nose
index = 152 - i;
L = -1;
}
var x = shape[index];
var spineNode = spine[shape[index+1]]; // get the equivalent spine position from the dragon shape
if (index >= 56) { // draw tail
var wobbleIndex = 56 - index; // table wobbles more towards the end
var wobble = Ms(wobbleIndex / 3 + pfloat * 0.1) * wobbleIndex * L;
x = 20 - index / 4 + wobble;
// override the node for the correct tail position
spineNode = spine[ index * 2 - 83 ];
} else if (index > 13) { // draw "flappy wings"
// 4 is hinge point
x = 4 + (x-4) * (Ms(( -x / 2 + pfloat) / 25 * speed / 4) + 2) * 2; // feed x into sin to make wings "bend"
// override the perpindicular lines for the wings
spineNode.px = Mc(wingPerpendicular);
spineNode.py = Ms(wingPerpendicular);
}
c.lineTo(
(spineNode.x + x * L * spineNode.px) * scale,
(spineNode.y + x * L * spineNode.py) * scale
);
}
c.fill();
}
}
// the shape of the dragon, converted from a SVG image
'! ((&(&*$($,&.)/-.0,4%3"7$;(#/EAA<?:<9;;88573729/7,6(8&;'.split("").map(function(a,i) {
shape[i] = a.charCodeAt(0) - 32;
});
loop();
While the context this is used in is <canvas>, the origin may well be a SVG <polyline>.
In a first step, the letters are mapped to numbers. A bit of obscuration, but nothing too serious: get the number representing the letter and write it to an array.
const shape = [];
'! ((&(&*$($,&.)/-.0,4%3"7$;(#/EAA<?:<9;;88573729/7,6(8&;'.split("").map(function(a,i) {
shape[i] = a.charCodeAt(0) - 32;
});
results in an array
[1,0,8,8,6,8,6,10,4,8,4,12,6,14,9,15,13,14,16,12,20,5,19,2,23,4,27,8,32,15,37,33,33,28,31,26,28,25,27,27,24,24,21,23,19,23,18,25,15,23,12,22,8,24,6,27]
Now just write this array to a points attribute of a polyline, joining the numbers with a space character:
const outline = document.querySelector('#outline');
const shape = [];
'! ((&(&*$($,&.)/-.0,4%3"7$;(#/EAA<?:<9;;88573729/7,6(8&;'.split("").map(function(a,i) {
shape[i] = a.charCodeAt(0) - 32;
});
outline.setAttribute('points', shape.join(' '))
#outline {
stroke: black;
stroke-width: 0.5;
fill:none;
}
<svg viewBox="0 0 77 77" width="300" height="300">
<polyline id="outline" />
</svg>
and you get the basic outline of (half) a dragon. The rest is repetition and transformation to make things a bit more complex.

Wrapping long text in d3.js

I want to wrap long text elements to a width. The example here is taken from Bostock's wrap function, but seems to have 2 problems: firstly the result of wrap has not inherited the element's x value (texts are shifted left); secondly it's wrapping on the same line, and lineHeight argument has no effect.
Grateful for suggestions. http://jsfiddle.net/geotheory/bk87ja3g/
var svg = d3.select("body").append("svg")
.attr("width", 300)
.attr("height", 300)
.style("background-color", '#ddd');
dat = ["Ukip has peaked, but no one wants to admit it - Nigel Farage now resembles every other politician",
"Ashley Judd isn't alone: most women who talk about sport on Twitter face abuse",
"I'm on list to be a Mars One astronaut - but I won't see the red planet"];
svg.selectAll("text").data(dat).enter().append("text")
.attr('x', 25)
.attr('y', function(d, i){ return 30 + i * 90; })
.text(function(d){ return d; })
.call(wrap, 250);
function wrap(text, width) {
text.each(function() {
var text = d3.select(this),
words = text.text().split(/\s+/).reverse(),
word,
line = [],
lineNumber = 1,
lineHeight = 1.2, // ems
y = text.attr("y"),
dy = parseFloat(text.attr("dy")),
tspan = text.text(null).append("tspan").attr("x", 0).attr("y", y).attr("dy", dy + "em");
while (word = words.pop()) {
line.push(word);
tspan.text(line.join(" "));
if (tspan.node().getComputedTextLength() > width) {
line.pop();
tspan.text(line.join(" "));
line = [word];
tspan = text.append("tspan").attr("x", 0).attr("y", y).attr("dy", ++lineNumber * lineHeight + dy + "em").text(word);
}
}
});
}
Bostock's original function assumes that the text element has an initial dy set. It also drops any x attribute on the text. Finally, you changed the wrap function to start at lineNumber = 1, that needs to be 0.
Refactoring a bit:
function wrap(text, width) {
text.each(function() {
var text = d3.select(this),
words = text.text().split(/\s+/).reverse(),
word,
line = [],
lineNumber = 0, //<-- 0!
lineHeight = 1.2, // ems
x = text.attr("x"), //<-- include the x!
y = text.attr("y"),
dy = text.attr("dy") ? text.attr("dy") : 0; //<-- null check
tspan = text.text(null).append("tspan").attr("x", x).attr("y", y).attr("dy", dy + "em");
while (word = words.pop()) {
line.push(word);
tspan.text(line.join(" "));
if (tspan.node().getComputedTextLength() > width) {
line.pop();
tspan.text(line.join(" "));
line = [word];
tspan = text.append("tspan").attr("x", x).attr("y", y).attr("dy", ++lineNumber * lineHeight + dy + "em").text(word);
}
}
});
}
Updated fiddle.
The problem is this line:
dy = parseFloat(text.attr("dy"))
In the example you've linked to, dy is set on the text elements, but not in your case. So you're getting NaN there which in turn causes the dy for the tspan to be NaN. Fix by assigning 0 to dy if NaN:
dy = parseFloat(text.attr("dy")) || 0
Complete demo here.

Read inner and outer radius of arc - d3.js

I'm working on a project which deals with visual representation of large relational data. We are using pie chart to display the data components(In order). Due to lack of space we are displaying only 10 at a time.
Consider the following example:
Assume that I have 100 data components, out of which I'll display only 10 at a given point of time. The logic i'm using is, I'm setting start and end angle to 0(Zero) for other 90 components. Where in for those 10 components i'm calculation the start and end angle as below-
var angle = 360;
var count = 10;
if(data.length > count) angle = angle/count; //data is array of data component names
else angle = angle/data.length;
//Initially I'll be displaying first ten components
for(var i=0; i<data.length; i++){
var startAngle = i * angle;
var endAngle = startAngle + angle;
var pi = = Math.PI/180;
var arc = d3.svg.arc()
.innerRadius(innerRadius) //dynamic value, calculated based on available space
.outerRadius(outerRadius) //dynamic value, calculated based on available space
.startAngle((startAngle)*pi)
.endAngle((endAngle)*pi);
//Hiding rest of the data components
if(i >= count){
arc.startAngle(0);
arc.endAngle(0);
}
arcGroup.append("path")
.attr("d", arc)
.attr("stroke", "#2E2E2E")
.attr("stroke-width", "1")
.attr("fill","gold");
var text = arcGroup.append("text")
.attr("transform", "translate(" + arc.centroid() + ")")
.attr("text-anchor", "middle")
.attr("font-family","noto_sansregular")
.attr("font-size", 40)
.attr("font-weight","Bold")
.attr("fill", "#000000")
.attr("y",0)
.style("visibility", "visible")
.text(data[i]);
//Hiding text of hidden arcs
if(i >= count) text.style("visibility", "hidden");
}
Then if user wants to see the rest of the components, i'm providing two buttons to rotate (clock or anti-clock) the content.
If current view is -> 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
On rotate by one cell clockwise, resulting view should be -> 100, 1, 2, 3, 4, 5, 6, 7, 8, 9
In this case I need to hide component '10' and display component '100', and shift rest of the cells. To achieve this i just need to change the start and end angles of the arcs. I can create new arc object with calculated angles.
The problem here is I don't know how to get the inner and outer radius of the arc, which are dynamically created.
Just like that,
...
arcGroup.append("path")
.filter(function(d) {
// You're Not restricted to the "filter" function
var innerRadius = d.innerRadius()(d);
var outerRadius = d.outerRadius()(d);
})
.attr("d", arc)
...
Technically, it is possible to retrieve the innerRadius and outerRadius from the d attribute of the path elements, but it will require parsing the DSL and will be tedious. These values are not stored nicely on the elements itself by d3.
Hence, it would be better if you recompute the innerRadius and outerRadius while updating the elements:
function showFromIdx(firstIndex) {
argGroup.selectAll('path')
.data( d3.range(data.length)
.map(function (d) {
return (d - firstIndex + data.length) % data.length;
})
)
.attr('d', function (d) {
// You will have to calculate the radii again here.
var innerRadius = foo(d), outerRadius = bar(d);
return d3.svg.arc()
.startAngle(i < count ? i * angle : 0)
.endAngle(i < count ? (i + 1) * angle : 0)
.innerRadius(innerRadius)
.outerRadius(outerRadius)(d);
});
}
Here are several functions that I wrote to get inner and outer radiuses of arcs created using d3. Please tell me if you find mistakes in code.
function getInnerRadiusFromArc(arc) {
var numbersInPattern = _getArcNumbers(arc);
// Possibly, that's sector, so it starts from 0.
// Or maybe that's something else.
if (numbersInPattern.length < 4) {
return 0;
}
// Getting minimum from the array.
var innerRadius = Math.min.apply(null, numbersInPattern);
return innerRadius;
}
function getOuterRadiusFromArc(arc) {
var numbersInPattern = _getArcNumbers(arc);
// Getting maximum from the array.
var outerRadius = Math.max.apply(null, numbersInPattern);
return outerRadius;
}
function _getArcNumbers(arc) {
// Path description parameter, containing necessary data.
var pathDescription = arc.getAttribute("d");
// We need to get all patterns like A<number>,<number>.
// RegExp source:
// http://www.regular-expressions.info/floatingpoint.html
const numberRegExp = /[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?/g;
var arcPattern = new RegExp("A" + numberRegExp.source + "," + numberRegExp.source, "g");
var arcParameters = pathDescription.match(arcPattern);
var numbersInPattern = [];
// We get all the numbers from array ["A<number>,<number>", "A<number>,<number>", ...].
for (let parameterIndex = 0; parameterIndex < arcParameters.length; parameterIndex++) {
let parameter = arcParameters[parameterIndex];
let numbers = parameter.match(numberRegExp);
if (numbers !== null) {
numbersInPattern = numbersInPattern.concat(numbers);
}
}
// Transform strings in our array to numbers.
numbersInPattern = numbersInPattern.map(function (numberString) {
return parseFloat(numberString);
});
return numbersInPattern;
}

How is the getBBox() SVGRect calculated?

I have a g element that contains one or more path elements. As I mentioned in another question, I scale and translate the g element by computing a transform attribute so that it fits on a grid in another part of the canvas.
The calculation is done using the difference between two rectangles, the getBBox() from the g element and the rectangle around the grid.
Here is the question -- after I do the transform, I update the contents of the g element and call getBBox() again, without removing the transform. The resulting rectangle appears to be calculated without considering the transform. I would have expected it to reflect the change. Is this behavior consistent with the SVG specification? How do I get the bounding box of the transformed rectangle?
This, BTW, is in an HTML 5 document running in Firefox 4, if that makes any difference.
Update: Apparently this behavior seems pretty clearly in violation of the specification. From the text here at w3c:
SVGRect getBBox()
Returns the tight bounding box in current user space (i.e., after application of the ‘transform’ attribute, if any) on the geometry of all contained graphics elements, exclusive of stroking, clipping, masking and filter effects). Note that getBBox must return the actual bounding box at the time the method was called, even in case the element has not yet been rendered.
Am I reading this correctly? If so this seems to be an errata in the SVG implementation Firefox uses; I haven't had a chance to try any other. I would file a bug report if someone could point me to where.
People often get confused by the behavioral difference of getBBox and getBoundingClientRect.
getBBox is a SVG Element's native method as equivalent to find the offset/clientwidth of HTML DOM element. The width and height is never going to change even when the element is rotated. It cannot be used for HTML DOM Elements.
getBoundingClientRect is common to both HTML and SVG elements. The bounded rectangle width and height will change when the element is rotated or when more elements are grouped.
The behaviour you see is correct, and consistent with the spec.
The transform gets applied, then the bbox is calculated in "current user units", i.e. the current user space. So if you want to see the result of a transform on the element you'd need to look at the bbox of a parent node or similar.
It's a bit confusing, but explained a lot better in the SVG Tiny 1.2 spec for SVGLocatable
That contains a number of examples that clarify what it's supposed to do.
there are at least 2 easy but somewhat hacky ways to do what you ask... if there are nicer (less hacky) ways, i haven't found them yet
EASY HACKy #1:
a) set up a rect that matches the "untransformed" bbox that group.getBBox() is returning
b) apply the group's "unapplied transform" to that rect
c) rect.getBBox() should now return the bbox you're looking for
EASY HACKY #2: (only tested in chrome)
a) use element.getBoundingClientRect(), which returns enough info for you to construct the bbox you're looking for
Apparently getBBox() doesn't take the transformations into consideration.
I can point you here, unfortunately I wasn't able to make it working: http://tech.groups.yahoo.com/group/svg-developers/message/22891
SVG groups have nasty practice - not to accumulate all transformations made. I have my way to cope with this issue. I'm using my own attributes to store current transformation data which I include in any further transformation. Use XML compatible attributes like alttext, value, name....or just x and y for storing accumulated value as atribute.
Example:
<g id="group" x="20" y="100" transform="translate(20, 100)">
<g id="subgroup" alttext="45" transform="rotate(45)">
<line...etc...
Therefore when I'm making transformations I'm taking those handmade attribute values, and when writing it back, I'm writing both transform and same value with attributes I made just for keeping all accumulated values.
Example for rotation:
function symbRot(evt) {
evt.target.ondblclick = function () {
stopBlur();
var ptx=symbG.parentNode.lastChild.getAttribute("cx");
var pty=symbG.parentNode.lastChild.getAttribute("cy");
var currRot=symbG.getAttributeNS(null, "alttext");
var rotAng;
if (currRot == 0) {
rotAng = 90
} else if (currRot == 90) {
rotAng = 180
} else if (currRot == 180) {
rotAng = 270
} else if (currRot == 270) {
rotAng = 0
};
symbG.setAttributeNS(null, "transform", "rotate(" + rotAng + "," + ptx + ", " + pty + ")");
symbG.setAttributeNS(null, "alttext", rotAng );
};
}
The following code takes into account the transformations (matrix or otherwise) from parents, itself, as well as children. So, it will work on a <g> element for example.
You will normally want to pass the parent <svg> as the third argument—toElement—as to return the computed bounding box in the coordinate space of the <svg> (which is generally the coordinate space we care about).
/**
* #param {SVGElement} element - Element to get the bounding box for
* #param {boolean} [withoutTransforms=false] - If true, transforms will not be calculated
* #param {SVGElement} [toElement] - Element to calculate bounding box relative to
* #returns {SVGRect} Coordinates and dimensions of the real bounding box
*/
function getBBox(element, withoutTransforms, toElement) {
var svg = element.ownerSVGElement;
if (!svg) {
return { x: 0, y: 0, cx: 0, cy: 0, width: 0, height: 0 };
}
var r = element.getBBox();
if (withoutTransforms) {
return {
x: r.x,
y: r.y,
width: r.width,
height: r.height,
cx: r.x + r.width / 2,
cy: r.y + r.height / 2
};
}
var p = svg.createSVGPoint();
var matrix = (toElement || svg).getScreenCTM().inverse().multiply(element.getScreenCTM());
p.x = r.x;
p.y = r.y;
var a = p.matrixTransform(matrix);
p.x = r.x + r.width;
p.y = r.y;
var b = p.matrixTransform(matrix);
p.x = r.x + r.width;
p.y = r.y + r.height;
var c = p.matrixTransform(matrix);
p.x = r.x;
p.y = r.y + r.height;
var d = p.matrixTransform(matrix);
var minX = Math.min(a.x, b.x, c.x, d.x);
var maxX = Math.max(a.x, b.x, c.x, d.x);
var minY = Math.min(a.y, b.y, c.y, d.y);
var maxY = Math.max(a.y, b.y, c.y, d.y);
var width = maxX - minX;
var height = maxY - minY;
return {
x: minX,
y: minY,
width: width,
height: height,
cx: minX + width / 2,
cy: minY + height / 2
};
}
I made a helper function, which returns various metrics of svg element (also bbox of transformed element).
The code is here:
SVGElement.prototype.getTransformToElement =
SVGElement.prototype.getTransformToElement || function(elem) {
return elem.getScreenCTM().inverse().multiply(this.getScreenCTM());
};
function get_metrics(el) {
function pointToLineDist(A, B, P) {
var nL = Math.sqrt((B.x - A.x) * (B.x - A.x) + (B.y - A.y) * (B.y - A.y));
return Math.abs((P.x - A.x) * (B.y - A.y) - (P.y - A.y) * (B.x - A.x)) / nL;
}
function dist(point1, point2) {
var xs = 0,
ys = 0;
xs = point2.x - point1.x;
xs = xs * xs;
ys = point2.y - point1.y;
ys = ys * ys;
return Math.sqrt(xs + ys);
}
var b = el.getBBox(),
objDOM = el,
svgDOM = objDOM.ownerSVGElement;
// Get the local to global matrix
var matrix = svgDOM.getTransformToElement(objDOM).inverse(),
oldp = [[b.x, b.y], [b.x + b.width, b.y], [b.x + b.width, b.y + b.height], [b.x, b.y + b.height]],
pt, newp = [],
obj = {},
i, pos = Number.POSITIVE_INFINITY,
neg = Number.NEGATIVE_INFINITY,
minX = pos,
minY = pos,
maxX = neg,
maxY = neg;
for (i = 0; i < 4; i++) {
pt = svgDOM.createSVGPoint();
pt.x = oldp[i][0];
pt.y = oldp[i][1];
newp[i] = pt.matrixTransform(matrix);
if (newp[i].x < minX) minX = newp[i].x;
if (newp[i].y < minY) minY = newp[i].y;
if (newp[i].x > maxX) maxX = newp[i].x;
if (newp[i].y > maxY) maxY = newp[i].y;
}
// The next refers to the transformed object itself, not bbox
// newp[0] - newp[3] are the transformed object's corner
// points in clockwise order starting from top left corner
obj.newp = newp; // array of corner points
obj.width = pointToLineDist(newp[1], newp[2], newp[0]) || 0;
obj.height = pointToLineDist(newp[2], newp[3], newp[0]) || 0;
obj.toplen = dist(newp[0], newp[1]);
obj.rightlen = dist(newp[1], newp[2]);
obj.bottomlen = dist(newp[2], newp[3]);
obj.leftlen = dist(newp[3], newp[0]);
// The next refers to the transformed object's bounding box
obj.BBx = minX;
obj.BBy = minY;
obj.BBx2 = maxX;
obj.BBy2 = maxY;
obj.BBwidth = maxX - minX;
obj.BBheight = maxY - minY;
return obj;
}
and full functional example is here:
http://jsbin.com/acowaq/1

Turtle graphics in SVG?

Is there a equivalent in svg path to logo's turtlegraphics?
instead of the hardcoded x and y coordinates, which also force me to adjust controlpoints on shifting a more relative "delta" approach.
My solution should work for the FOCS (Firefox Opera Chrome Safaries ex IE) browsers.
regards
Jeroen.
Edit: I made a live-editing webapp out of this concept: http://forresto.github.com/turtle-svg/
If you want to make a SVG path with turtle graphics (with rotation) in JavaScript it doesn't take much math:
// Turtle graphics drawing to SVG path
var TAU = 2 * Math.PI;
var pen = true;
var d = "";
var vector = {
x: 0,
y: 1
};
var currentAngle = 0;
// Relative turns, angles are 0.0 to 1.0
var turnRight = function(angle){
currentAngle += angle;
currentAngle = currentAngle%1;
vector.x = Math.sin(TAU*currentAngle);
vector.y = Math.cos(TAU*currentAngle);
};
var turnLeft = function(angle){
turnRight(-angle);
};
// Absolute turn
var turnTo = function(angle){
currentAngle = angle;
vector.x = Math.sin(TAU*currentAngle);
vector.y = Math.cos(TAU*currentAngle);
};
// Drawing
var penUp = function(){
pen = false;
};
var penDown = function(){
pen = true;
};
// Relative moves
var moveForward = function (distance) {
d += pen ? "l " : "m ";
d += (distance * vector.x) + " " + (distance * vector.y) + " ";
}
// Absolute moves
var moveTo = function (x, y) {
d += pen ? "L " : "M ";
d += x + " " + y + " ";
}
And then set your path d to the generated d. See it in action with some recursive drawing: http://jsfiddle.net/forresto/hVE2U/
1st Google result for SVG Path: http://www.w3schools.com/svg/svg_path.asp
Quote: "Capital letters means absolutely positioned, lower cases means relatively positioned."

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