Any way to stretch/collapse canvas grid in fabric js? - fabricjs

I am thinking of stretching/collapsing the canvas grid using input fields. I tried the grid.js also. But this is not for fabric js, though i tried hard.
Is it possible to stretch/collapse the canvas grid by user input?

I have come up with a solution using some other guys solution those I did find in jsfiddle but I cannot find that reference link right now. I just have customized that solution to work with my code. Thanks to that guy. Here is my solution -
function draw_grid(grid_size) {
grid_size || (grid_size = 25);
currentCanvasWidth = canvas.getWidth();
currentcanvasHeight = canvas.getHeight();
// Drawing vertical lines
var x;
for (x = 0; x <= currentCanvasWidth; x += grid_size) {
this.grid_context.moveTo(x + 0.5, 0);
this.grid_context.lineTo(x + 0.5, currentCanvasHeight);
}
// Drawing horizontal lines
var y;
for (y = 0; y <= currentCanvasHeight; y += grid_size) {
this.grid_context.moveTo(0, y + 0.5);
this.grid_context.lineTo(currentCanvasWidth, y + 0.5);
}
grid_size = grid_size;
this.grid_context.strokeStyle = "black";
this.grid_context.stroke();
}
I hope this will someone someday.

Related

Phaser 3 - Fix a shape into the camera view

I am trying to draw a minimap from a randomly generated matrix that represents my level.
To do so, I am drawing black or white little squares one by one to represent the matrix visually (I don't know if it the best way to do that with phaser, actually, I am a beginner with this framework).
The map draws correctly but its position is bound to the world not to camera, so when I move it is not visible anymore.
Here is the code I use to draw the map:
generate() {
let wallsGraphics = this._scene.add.graphics({fillStyle : {color : LabyrinthConfig.MAPS.MINI_MAP.WALLS_COLOR}});
let pathGraphics = this._scene.add.graphics({fillStyle : {color : LabyrinthConfig.MAPS.MINI_MAP.PATH_COLOR}});
// Draw the map
let y = 0;
for (let line of this._matrix) {
let x = 0;
for (let cell of line) {
let rect = new Phaser.Geom.Rectangle();
rect.width = LabyrinthConfig.MAPS.MINI_MAP.CELL_WIDTH;
rect.height = LabyrinthConfig.MAPS.MINI_MAP.CELL_HEIGHT;
rect.x = LabyrinthConfig.MAPS.MINI_MAP.POSITION_X + x * LabyrinthConfig.MAPS.MINI_MAP.CELL_WIDTH;
rect.y = LabyrinthConfig.MAPS.MINI_MAP.POSITION_Y + y * LabyrinthConfig.MAPS.MINI_MAP.CELL_HEIGHT;
cell === 0 ? wallsGraphics.fillRectShape(rect) : pathGraphics.fillRectShape(rect);
x++;
}
y++;
}
}
Any help on how to fix this map to the camera view ?
Set scroll factor of your graphics objects to 0.
wallsGraphics.setScrollFactor(0);
pathGraphics.setScrollFactor(0);

Smoothing pixel-by-pixel drawing in Processing

I picked up Processing today, and wrote a program to generate a double slit interference pattern. After tweaking with the values a little, it works, but the pattern generated is fuzzier than what is possible in some other programs. Here's a screenshot:
As you can see, the fringes are not as smooth at the edges as I believe is possible. I expect them to look like this or this.
This is my code:
// All quantities in mm
float slit_separation = 0.005;
float screen_dist = 50;
float wavelength = 5e-4f;
PVector slit1, slit2;
float scale = 1e+1f;
void setup() {
size(500, 500);
colorMode(HSB, 360, 100, 1);
noLoop();
background(255);
slit_separation *= scale;
screen_dist *= scale;
wavelength *= scale;
slit1 = new PVector(-slit_separation / 2, 0, -screen_dist);
slit2 = new PVector(slit_separation / 2, 0, -screen_dist);
}
void draw() {
translate(width / 2, height / 2);
for (float x = -width / 2; x < width / 2; x++) {
for (float y = -height / 2; y < height / 2; y++) {
PVector pos = new PVector(x, y, 0);
float path_diff = abs(PVector.sub(slit1, pos).mag() - PVector.sub(slit2, pos).mag());
float parameter = map(path_diff % wavelength, 0, wavelength, 0, 2 * PI);
stroke(100, 100, pow(cos(parameter), 2));
point(x, y);
}
}
}
My code is mathematically correct, so I am wondering if there's something wrong I am doing in transforming the physical values to pixels on screen.
I'm not totally sure what you're asking- what exactly do you expect it to look like? Would it be possible to narrow this down to a single line that's misbehaving instead of the nested for loop?
But just taking a guess at what you're talking about: keep in mind that Processing enables anti-aliasing by default. To disable it, you have to call the noSmooth() function. You can call it in your setup() function:
void setup() {
size(500, 500);
noSmooth();
//rest of your code
It's pretty obvious if you compare them side-by-side:
If that's not what you're talking about, please post an MCVE of just one or two lines instead of a nested for loop. It would also be helpful to include a mockup of what you'd expect versus what you're getting. Good luck!

Pixi.js how to render texture on polygon

I want to render a texture on polygon using pixi.js, sprites just offer me a square option. i need to change that (top, left), (top, right), (bottom, left), (bottom, right) in order to render a imagen inside it.
http://cl.ly/image/1s2Y2f331h0a/Screen%20Shot%202013-12-16%20at%203.11.02%20PM.png
how can i resolve this?
something like, beginFillBitmap or any other way?
Same here :) I'm investigating if pixi is suitable for my project and the last thing I need is rendering textures on non-rectangles.
Only thing I have found so far is masking:
http://www.goodboydigital.com/pixi-js-brings-canvas-and-webgl-masking/ . Maybe this can help you.
But it is not enough good for me. I need also ability to repeat texture in X and Y axis. Any other ideas? Or is there another js html5 framework that has that ability?
Use PIXI.mesh.Mesh with Pixi v4 or PIXI.SimpleMesh with Pixi v5.
This is a simple example that works with all kind of renderers (you can paste it in the Pixi Examples page https://pixijs.io/examples-v4/?v=release ):
var app = new PIXI.Application(800, 600, { backgroundColor: 0x1099bb });
document.body.appendChild(app.view);
// create 3 vertex 2D positions (x, y)
var meshv = new Float32Array(2*3);
var i = 0;
meshv[i++] = 0; meshv[i++] = 0;
meshv[i++] = 100; meshv[i++] = 0;
meshv[i++] = 100; meshv[i++] = 100;
// create 3 vertex texture coordinate UV positions (u,v)
var meshuv = new Float32Array(2*3);
i = 0;
meshuv[i++] = 0; meshuv[i++] = 0;
meshuv[i++] = 1; meshuv[i++] = 0;
meshuv[i++] = 1; meshuv[i++] = 1;
// create 1 triangle indexes (i1, i2, i3) referencing indexes in the other two arrays
var meshi = new Uint16Array(1*3);
i = 0;
meshi[i++] = 0; meshi[i++] = 1; meshi[i++] = 2;
// create the mesh object
var mesh = new PIXI.mesh.Mesh(
PIXI.Texture.fromImage('examples/assets/bunny.png'),
meshv, meshuv, meshi, PIXI.DRAW_MODES.TRIANGLES
);
// attach to the stage, container...
app.stage.addChild(mesh);
You can also use newer Pixi v5 features to a more advanced example like in https://pixijs.io/examples/#/mesh/triangle-textured.js but can be less compatible.
Edit: for wrapping modes (for repeating the texture) check http://pixijs.download/dev/docs/PIXI.BaseTexture.html wrap mode options.

D3 force layout with CSS positioning

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';});
});

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

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