I've been experimenting with trigonometry for the past few days, and came up with one of those neat stat pentagons you find in some games. (fiddle!)
I'd really like to allow the vertices of the inner polygon to be draggable to change the stat values. I have mouse functionality working well, but what's the best way to drag a point on the line with the mouse?
I've created a picture to visualize my problem; the red polygon is the "current" polygon, the pink lines represent the new polygon, the pink circle emphasizes the new point for the vertex, the blue line is the vector tangent, and the green circle is the cursor.
I've written a program which deals with vectors before, but I'm not sure how to apply it to this situation.
Here's some code (in the loop function):
for(var i = 0; i < innerPolygonKnobs.length; i ++){
var knob = innerPolygonKnobs[i];
distX = knob.x-mouse.x;
distY = knob.y-mouse.y;
distTotal = Math.sqrt(distX*distX + distY*distY);
if(distTotal < 8){
if(!knob.over)change = true;
knob.over = true;
if(mouse.down){
// What goes here?
}
} else {
if(knob.over)change = true;
knob.over = false;
}
}
if(change)redraw();
Thanks so much in advance! :D
This function will give you the closest point to the mouse on any given line:
// given a line defined like this
var line={x0:50,y0:50,x1:150,y1:150};
// calculate the closest point on the line to [x,y]
function getClosestPointOnLine(line,x,y) {
//
lerp=function(a,b,x){ return(a+x*(b-a)); };
var dx=line.x1-line.x0;
var dy=line.y1-line.y0;
var t=((x-line.x0)*dx+(y-line.y0)*dy)/(dx*dx+dy*dy);
t=Math.min(1,Math.max(0,t));
var lineX=lerp(line.x0, line.x1, t);
var lineY=lerp(line.y0, line.y1, t);
return({x:lineX,y:lineY});
};
Then just redraw your inner polygon to connect to the point found above.
Interesting app...good luck with it!
Related
As you can see on attached image it has the rhombus with the ellipse inside which is almost transparent.
But this is just an image.
How can I create this with createjs?
A more detailed description of the problem:
What you see in the picture is not exactly what I need.
Ideally, my task is to make two triangles out of this rhombus with an ellipse inside.
The ellipse should create some kind of transparency in the triangle so that all the elements that will be under this triangle are visible through.
My implementation:
I make a triangle according to this example:
(thank to this fiddle)
(createjs.Graphics.Polygon = function(x, y, points) {
this.x = x;
this.y = y;
this.points = points;
}).prototype.exec = function(ctx) {
// Start at the end to simplify loop
var end = this.points[this.points.length - 1];
ctx.moveTo(end.x, end.y);
this.points.forEach(function(point) {
ctx.lineTo(point.x, point.y);
});
};
createjs.Graphics.prototype.drawPolygon = function(x, y, args) {
var points = [];
if (Array.isArray(args)) {
args.forEach(function(point) {
point = Array.isArray(point) ? {x:point[0], y:point[1]} : point;
points.push(point);
});
} else {
args = Array.prototype.slice.call(arguments).slice(2);
var px = null;
args.forEach(function(val) {
if (px === null) {
px = val;
} else {
points.push({x: px, y: val});
px = null;
}
});
}
return this.append(new createjs.Graphics.Polygon(x, y, points));
};
stage = new createjs.Stage("demoCanvas");
poly1 = new createjs.Shape();
poly1.graphics.beginFill("Red").drawPolygon(0,0,10,10,10,40,40,30,60,5,30,0);
poly1.x = 10;
poly1.y = 10;
stage.addChild(poly1);
stage.update();
(if there is a more convenient or even correct way to make a triangle and this will help in solving my problem, I will gladly accept your solution).
Next, I simply overlay the ellipse drawn with drawEllipse on top of this triangle.
I understand that I may be doing something wrong, and that is why I am here.
Any help will be accepted!
I assume you are using the Graphics API to draw your content. If so, you simply need to ensure the "hole" draws with reverse winding. This just means the shape needs to be drawn in the reverse direction.
For example, the Canvas2D rect method draws clockwise, so to subtract from them, the instructions need to be drawn in the other direction.
var s = new createjs.Shape();
s.graphics.beginFill("red")
.drawRect(0,0,300,300) // Draw a square
// Then draw a smaller square
.moveTo(100,100) // Top left
.lineTo(100,200) // Bottom left
.lineTo(200,200) // Bottom right
.lineTo(200,100) // Top right
.lineTo(100,100) // Top left
.closePath(); // Optional if you are done
The drawEllipse has an anticlockwise parameter which does the trick as well. Here is a jsfiddle sample, which actually draws it the other way (small cut-out first), but with the same result.
UPDATE
In order for the shape to "cut out" the other one, it has to be part of the same graphics instance, and part of the same path instructions. If you closePath() after any drawing instructions, any new instructions are drawn on top of that without cutting it out. Using separate shape instances does this automatically.
Using the updated code, I added a simple drawEllipse() call using default clockwise winding, and it cut out the circle: https://jsfiddle.net/lannymcnie/yd25h8se/ -- Note that I scaled up the coordinates from above x10 to make it more visible.
Cheers,
Three.js r85
When raycasting with Three JS, a series of points is returned, and I'd like to find the point that is closest to the cursor. The first point returned seems to be the point that is closest to the camera.
Is there a way to find the distance between the cursor position and a point?
Here's the code I'm using to debug this right now:
var raygun = new THREE.Raycaster();
raygun.setFromCamera(mouse, camera);
var hits = raygun.intersectObjects([plotpoints]);
if (hits.length > 0) {
scope.remove(dotPlot);
scope.remove(dotPlot2);
// All points except the first one - Grey
dotGeo = new THREE.Geometry();
for (var i=1; i < hits.length; i++) {
dotGeo.vertices.push(plotpoints.geometry.vertices[hits[i].index]);
}
dotPlot = new THREE.Points(dotGeo, dotMat);
scope.add(dotPlot);
// First point - Orange
var geo2 = new THREE.Geometry();
geo2.vertices.push(plotpoints.geometry.vertices[hits[0].index]);
dotPlot2 = new THREE.Points(geo2, dotMat2);
scope.add(dotPlot2);
scope.render();
}
And here's what I'm seeing:
Ah, figured it out with math!
First thing to note is that hits[].points returns a point directly under the cursor, but it doesn't "snap" to points.
In order to get the actual position of the point, we need to use hits[].index first to get the index number of the point/vertex we hit. We can then access that vertex directly by using GEOMETRY.vertices[] which returns a THREE.Vector3 of the vertex point we hit with our raycast.
So by feeding in the index, we can get the exact position of each vertex hit by our raycast:
GEOMETRY.vertices[hits[i].index]
This provides rudimentary "snapping" to vertices.
Note: When using THREE.LineSegments, the result will always be the starting point, and not the ending point. To get the ending point, you can just add 1 to the index value:
GEOMETRY.vertices[hits[i+1].index]
To snap directly to the vertex closest to the cursor, we need to find the vertex that has the shortest perpendicular distance from the raycaster's ray. To do this we use a cross product of 2 vectors. This is more of a math concept than a programming concept though, so if you want to understand the why behind this, look up something like: perpendicular distance from a point to a line
I just took the code from this question and translated it: http://answers.unity3d.com/questions/568773/shortest-distance-from-a-point-to-a-vector.html
And the end result:
// Variables to record and compare
var smallestDist = 99;
var smallestPointIndex = 0;
// Declare variables outside of loop to save memory
var m_ray = raycaster.ray;
var raydir = m_ray.direction;
var origin = m_ray.origin;
var hitray = new THREE.Vector3(0,0,0);
var dist = 1;
// Loop over all points to find the closest
for (var i=0; i<hits.length; i++){
// Math is magic
hitray.subVectors(plotpoints.geometry.vertices[hits[i].index], origin);
dist = new THREE.Vector3().crossVectors(raydir, hitray).lengthSq();
// Record the closest point
if (dist < smallestDist) {
smallestDist = dist;
smallestPointIndex = i;
}
}
// Now we can use that single point
Here's the result :)
I am trying to make tooltips for a data visualization I made using p5.js but I am completely lost. Nothing I tried works. This is my code as is.
var table;
var i;
var j;
var cellValue;
var label;
var test;
function preload() {
matrix = loadTable("dataLayer2matrix.csv","csv")
labels = loadTable("dataLayer2labels.csv","csv")
test = matrix
}
function setup() {
createCanvas(1500,1500)
noStroke()
fill(0,0,255,10)
angleMode(DEGREES)
background(255,255,255)
matrixStartX = 200
matrixStartY = 250
var matrixRows = matrix.getRows()
var matrixSize = matrixRows.length
// Experiment with grid
fill(75, 75, 75, 50)
for (r = 0; r <= matrixSize; r++) {
rect(matrixStartX , matrixStartY + r * 20 - 1 , 20 * matrixSize, 1)
rect(matrixStartX + r * 20 - 1 , matrixStartY, 1, 20 * matrixSize)
}
// Draw matrix
for (var mr = 0; mr < matrixSize; mr++) {
for (var mc = 0; mc < matrixSize; mc++) {
cellValue = matrixRows[mr].getNum(mc)
fill(49,130,189,cellValue*10)
rect(mc * 20 + matrixStartX, mr * 20 + matrixStartY, 19 ,19)
}
}
// Labels - horizontal
fill(75, 75, 75, 255)
labelsRow = labels.getRows()
for (mc = 0; mc < matrixSize; mc++) {
label = labelsRow[0].getString(mc)
text(label, 10, mc*20+matrixStartY + 15)
}
// Labels - vertical
push()
translate(matrixStartX + 15, matrixStartY - 15)
rotate(-90)
for (mc = 0; mc < matrixSize; mc++) {
label = labelsRow[0].getString(mc)
text(label, 0, mc*20)
}
pop()
//Tooltip when clicked
}
/* if(mouseIsPressed){
fill(50);
text(cellValue, 10,10,70,80);
}*/
}
}
It makes this image:
I want it so that when I go over a square I get the data in it. I really can't seem to do it. Thanks.
I think the advice telling you to use bootstrap is missing the fact that you're using p5.js. Bootstrap is more for dealing with html components, not internal Processing sketches.
Instead, you probably want to do this with p5.js code. The best thing you can do is break your problem down into smaller steps:
Step 1: Can you draw a single rectangle?
Instead of trying to add this new functionality to your existing sketch, it might be easier if you start with a simpler example sketch with just a single rectangle.
Step 2: Can you detect when the mouse is inside that rectangle?
If you know where you're drawing the rectangle, you know its coordinates. You also know the coordinates of the mouse from the mouseX and mouseY variables. So to detect whether the mouse is inside the rectangle, you simply have to use if statements that compare the coordinates of the mouse to the coordinates of the rectangle. There are a ton of resources on google for this, and it might help if you draw some examples out on a piece of paper.
Also, don't worry about the tooltip just yet. Just do something simple like change the color of the rectangle when the mouse is inside it.
Step 3: Can you display the information box?
Again, do this in its own sketch first. Maybe create a function that takes a position and the information you want to display as parameters and displays it in a rectangle. Don't worry about making it a tooltip yet. Just get it displaying. Use hard-coded values for the information.
Step 4: Can you combine your small example sketches?
You have code that triggers when the mouse is inside a rectangle. You have code that draws the tooltip. Can you make it so the tooltip is drawn when the mouse is inside the rectangle?
Step 5: Only when all of the above works, then you should start thinking about adding it to your full sketch.
Instead of using an example rectangle, you'll have to use the rectangles you're drawing on the screen. Instead of calling the tooltip function with hard-coded values, use the values you get from the squares.
Take on those pieces one at a time, and make small steps toward your goal. Then if you get stuck, you can post an MCVE of the specific step you're on. Good luck!
I am struggling with camera functionality that (I think) would provide a way to force my polygon to stick to the top of my house on zoom-out, zoom-in, and rotation (or camera move).
This question follows an earlier question that was resolved. Now I need a little help resolving my next issue.
The sample code I am trying to follow is located in the gold standard that appears to be baked into the existing camera controller here.
pickGlobe is executed with the parameters of the viewer, the correct mousePosition in world coordinates and a result parameter, which I don't care about right now. scene.pickPosition takes the c2position (Cartesian2) and should return the scratchDepthIntersection (Cartesian3). Instead, the returned value is undefined.
Here is my code:
function clickAction(click) {
var cartesian = scene.camera.pickEllipsoid(click.position, ellipsoid);
if (cartesian) {
var setCartographic = ellipsoid.cartesianToCartographic(cartesian);
collection.latlonalt.push(
Cesium.Math.toDegrees(setCartographic.latitude).toFixed(15),
Cesium.Math.toDegrees(setCartographic.longitude).toFixed(15),
Cesium.Math.toDegrees(setCartographic.height).toFixed(15)
);
lla.push(Cesium.Math.toDegrees(setCartographic.longitude), Cesium.Math.toDegrees(setCartographic.latitude));
if (lla.length >= 4) {
console.log((lla.length / 2) + ' Points Added');
}
enableDoubleClick();
enableDraw();
testMe(click.position); <--------------------- straight from the mouse click
}
}
var pickedPosition;
var scratchZoomPickRay = new Cesium.Ray();
var scratchPickCartesian = new Cesium.Cartesian3();
function testMe(c2MousePosition) { <--------------------- straight from the mouse click
if (Cesium.defined(scene.globe)) {
if(scene.mode !== Cesium.SceneMode.SCENE2D) {
pickedPosition = pickGlobe(viewer, c2MousePosition, scratchPickCartesian);
} else {
pickedPosition = camera.getPickRay(c2MousePosition, scratchZoomPickRay).origin;
}
}
}
var pickGlobeScratchRay = new Cesium.Ray();
var scratchRayIntersection = new Cesium.Cartesian3();
var c2position = new Cesium.Cartesian2();
function pickGlobe(viewer, c2MousePosition, result) { <--------------------- straight from the mouse click
c2position = c2MousePosition; <--------------------- setting to Cartesian2
var scratchDepthIntersection = new Cesium.Cartesian3();
if (scene.pickPositionSupported) {
scratchDepthIntersection = scene.pickPosition(c2MousePosition); <--------------------- neither works!
}
}
Here are my variables:
Here is the result:
Here are my questions to get this code working:
1. Why is scratchDepthIntersection not getting set? c2position is a Cartesian2 and c2MousePosition is straight from the mouse.click.position and scratchDepthIntersection is a new Cartesian3.
The correct value for mousePosition is a Cartesian2 containing window coordinates, not a Cartesian3. Such mouse coordinates usually come from a callback from Cesium.ScreenSpaceEventHandler, but can also be constructed from native JavaScript mouse/touch events.
If you inspect the contents of mousePosition, you should find x and y values in window pixel coordinates.
I see you edited the question to include the contents of mousePosition, and it looks like the mouse coordinates have already been converted into ellipsoid Cartesian3 coordinates, which will prevent this code from working. You want original mouse coordinates going directly into scene.pickPosition for this to work.
As a very inexperienced programmer, I'm trying to code a game that detects when the player collides with certain colors on the canvas. I have a black square with coordinates "player.x" and "player.y" and dimensions 50x50 that moves around when you press the arrow keys. I also have a stationary red (255,0,0) square elsewhere on the canvas.
The function below is supposed to grab a slightly larger square around the "player" square and find out if there's any red in it. If there is, it will send up an alert. The problem is, this doesn't seem to be working.
function collideTest(){
var canvas = document.getElementById("canvas");
var c = canvas.getContext("2d");
var whatColor = c.getImageData(player.x - 5, player.y - 5,60,60);
for (var i = 0; i < 3600; i++) {
if (whatColor.data[i] == 255) {
alert("red");
}
}
}
I'm semi-aware that this is not the most efficient way to detect red pixels, but I wanted to simplify the code before posting it here. Is there something obviously wrong with the function?
The problem could lie in the way the function is called. It gets called at the end of another function that detects user-input and changes the coordinates of the "player" square. THAT function gets called right before everything is drawn on the canvas.
Thanks in advance for any help!
var whatColor = c.getImageData(player.x - 5, player.y - 5,60,60);
player.x and player.y must not be decimal, make sure they are rounded or getImageData will be angry and not play nice.
For each single pixel on the canvas, the whatColor.data array holds 4 sequential pieces of color information: red,green,blue,alpha(opacity). So the whatColor.data looks like this for each pixel:
whatColor.data[i] is the red component of the color.
whatColor.data[i+1] is the green component of the color.
whatColor.data[i+2] is the blue component of the color.
whatColor.data[i+3] is the alpha(opacity) component of the color.
So your iteration would look like this (4 indexes per pixel):
for(var i = 0, n = whatColor.data.length; i < n; i += 4) {
var red = whatColor.data[i];
var green = whatColor.data[i + 1];
var blue = whatColor.data[i + 2];
var alpha = whatColor.data[i + 3];
if(red==255){ ... it's a hit, do your thing! ... }
}
See here for a mini-tutorial on the imageData.data array: http://www.html5canvastutorials.com/advanced/html5-canvas-get-image-data-tutorial/
By the way, you might look at one of the canvas libraries that simplify game making with canvas. Here are just a few: easelJs, KineticJs, FabricJs, and more!