I have some P5js code that I made.
It basically moves the circle around the screen to predetermined targets stored in an array. I will be using it within my game that uses A* pathfinding and stores the path points in an array. I then am looking at moving the player to each of those points smoothly with the code below.
What I am asking
Most importantly, can this code be optimized/cleaner if so, how?
How can I allow for a larger speed value. Currently if I change the speed to 3, it doesnt trigger the if statement (I would need to cicle to be at the target within a 1 px varience regardless of spped).
Other notes
I tried using the P5 Lerp function however it did not allow for a constant movement speed.
Thank you :)
var targets
var target_index = 0
var position
var x_complete = true
var y_complete = true
var speed = 1
function setup() {
createCanvas(400, 400);
targets = [createVector(0, 0), createVector(50, 50), createVector(0, 0), createVector(0, 50), createVector(200, 200)]
position = targets[0]
}
var count = 0;
function draw() {
background(220);
move_c()
draw_c()
}
function draw_c() {
strokeWeight(10);
point(position.x, position.y);
}
function move_c() {
var x_needs_to_goes_up
var x_is_currently_smaller
var y_needs_to_goes_up
var y_is_currently_smaller
x_complete = false
y_complete = false
if (targets.length - 1 > target_index) {
x_needs_to_goes_up = !number_is_larger(targets[target_index].x, targets[target_index + 1].x) //X goes up
x_is_currently_smaller = number_is_smaller(targets[target_index].x, targets[target_index + 1].x)
y_needs_to_goes_up = !number_is_larger(targets[target_index].y, targets[target_index + 1].y) //X goes up
y_is_currently_smaller = number_is_smaller(targets[target_index].y, targets[target_index + 1].y)
if (x_needs_to_goes_up && x_is_currently_smaller) { //If x is currently smaller then target
move_x(true)
} else if (x_needs_to_goes_up && !x_is_currently_smaller) {
x_complete = true
}
if (!x_needs_to_goes_up && !x_is_currently_smaller) { //If x is currently smaller then target
move_x(false)
} else if (!x_needs_to_goes_up && x_is_currently_smaller) {
x_complete = true
}
if (y_needs_to_goes_up && y_is_currently_smaller) { //If x is currently smaller then target
move_y(true)
} else if (y_needs_to_goes_up && !y_is_currently_smaller) {
y_complete = true
}
if (!y_needs_to_goes_up && !y_is_currently_smaller) { //If x is currently smaller then target
move_y(false)
} else if (!y_needs_to_goes_up && y_is_currently_smaller) {
y_complete = true
}
if (y_complete && x_complete) {
target_index++
}
}
}
function move_y(up) {
if (up) {
position = createVector(targets[target_index].x, targets[target_index].y += speed)
} else {
position = createVector(targets[target_index].x, targets[target_index].y -= speed)
}
}
function move_x(up) {
if (up) {
position = createVector(targets[target_index].x += speed, targets[target_index].y)
} else {
position = createVector(targets[target_index].x -= speed, targets[target_index].y)
}
}
function number_is_larger(num1, num2) {
return num1 > num2 ? true : false
}
function number_is_smaller(num1, num2) {
return num1 < num2 - 1 ? true : false
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.js"></script>
The main problem in your code is that when you increase the speed you shoot over the target as you may not hit the target accurately.
First of all the initial position vector should be a copy of the first target:
position = targets[0].copy()
Calculate the vector from the position to the next target and the Euclidean lenght of the vector (this is the distance of the position to the next target:
let direction = p5.Vector.sub(targets[target_index], position)
let distance = direction.mag()
Distinguish whether the distance to the next target is greater or less than the speed:
if (distance <= speed) {
// less
// [...]
} else {
// greater
// [...]
}
If it is less, the next position is the next target and the target index need to be incremented:
position = targets[target_index].copy()
target_index ++;
If it is greater, make on step forwards. Calculate the normalized direction vector. A normalized vector is a Unit vector and has a length of 1. Multiply the vector with the speed. Now the vector is length the speed. Add the vector to the position:
position.add(direction.normalize().mult(speed))
var targets
var target_index = 0
var position
var speed = 3
function setup() {
createCanvas(400, 400);
targets = [createVector(0, 0), createVector(50, 50), createVector(0, 0), createVector(0, 50), createVector(200, 200)]
position = targets[0].copy()
}
function draw() {
background(220);
move_c()
draw_c()
}
function draw_c() {
strokeWeight(10);
point(position.x, position.y);
}
function move_c() {
if (targets.length - 1 > target_index) {
let direction = p5.Vector.sub(targets[target_index], position)
let distance = direction.mag()
if (distance <= speed) {
position = targets[target_index].copy()
target_index ++;
} else {
position.add(direction.normalize().mult(speed))
}
} else {
target_index = 0
}
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.1/p5.min.js"></script>
I'm pretty close to finish this program using Canvas. This program is simply a ball that falls down from top to bottom and there's a basket that catches it, that is it. However, I have the following issues.
1) When I press the left or right arrows from keyboard for more than couple of times somehow the basket will go all the way to either left or right and disappear.
2) When the ball hits the basket nothing happens (my Collision detection function doesn't work properly). However, I should say that my collision detection works just fine when the balls hits the ground (alert message shows up saying "Ball hit the ground").
Is there a way to show a message on the top of the canvas like "1 point" every time the basket catches a ball ( if there are 5 balls then I should get a message to say "5 points")
Can someone tell me what I am doing wrong please? Thank you so much in advance!!
LIVE CODE HERE
http://codepen.io/HenryGranados/pen/QNOZRa
Here's my code :
//create the constructor for the class pad
function Pad() {
//initialisation code will go here
//create private variables for the x and y coordinates
var x = 200,
y = 200,
vx = 0,
vy = 0,
padX = (canvas.width - 20) / 2;
rightPressed = false,
leftPressed = false;
//create the draw function to give us the draw method
//it accepts one parameter which is the context from the canvas it is drawn on
Pad.prototype.draw = function (context) {
//save the state of the drawing context before we change it
context.save();
//set the coordinates of the drawing area of the new shape to x and y
context.translate(x, y);
//start the line (path)
context.beginPath();
context.fillStyle = "#800000"; // This is the basket
context.moveTo(15, 20);
context.bezierCurveTo(20, 100, 150, 100, 150, 20);
//close the path
context.closePath();
context.fill();
//go ahead and draw the line
context.stroke();
//restore the state of the context to what it was before our drawing
context.restore();
}
//create a public property called X (note caps!)
Object.defineProperty(this, 'X',
{
//getter
get: function () {
//return the value of x (lower case)
return x;
},
//setter
set: function (value) {
//ste the value of x (lower case)
x = value;
}
}
)
//create a public property called Y (note caps!)
Object.defineProperty(this, 'Y',
{
//getter
get: function () {
//return the value of y (lower case)
return y;
},
//setter
set: function (value) {
//ste the value of y (lower case)
y = value;
}
}
)
padX = function () {
if (rightPressed && padX < canvas.width - 20) {
padX += 5;
}
else if (leftPressed && padX > 0) {
padX -= 5;
}
}
Pad.prototype.move = function () {
//change the x axis by the x velocity
x += vx;
//change the y axis by the y velocity
y += vy;
}
Pad.prototype.setVector = function (vector) {
//set the vx value based on this vector
vx = vector.VX;
//set the vy value based on this vector
vy = vector.VY;
}
//public method to set the vector of the saucer
Pad.prototype.accelerate = function (Acceleration) {
//set vx
vx += Acceleration.AX;
////set vy
//vy += Acceleration.AY;
}
//create a public property called Top
Object.defineProperty(this, 'Top',
{
//getter
get: function () {
//return the y posn less the height
return y - 10;
}
}
)
//create a public property called Bottom
Object.defineProperty(this, 'Bottom',
{
//getter
get: function () {
//return the y posn plus the height
return y + 10;
}
}
)
//create a public property called Left
Object.defineProperty(this, 'Left',
{
//getter
get: function () {
//return the x posn less the width
return x - 80;
}
}
)
//create a public property called Right
Object.defineProperty(this, 'Right',
{
//getter
get: function () {
//return the x posn plus the width
return x + 80;
}
}
)
}
(1) There are at least two options to solve this problem
in your Pad.move function you could limit the change of x. You change it only when its within canvas width:
Pad.prototype.move = function() {
//change the x axis by the x velocity
var canvasWidth = 400,
padWidth = 150;
if (x + vx < canvasWidth - padWidth && x + vx >= 0)
x += vx;
//change the y axis by the y velocity
y += vy;
}
or similarly as you create ground you could create walls on both sides and collide pad with them.
(2) There is no collision handling between ball and pad:
place it in function drawFrame():
if (collision.Overlapping(ball, pad)) {
context.strokeText('ball hit pad!',20,100)
//..do some other stuff here
}
(3)Which brings us to showing message on canvas, you can just draw text on canvas
var ctx = canvas.getContext("2d");
ctx.font = "30px Arial";
ctx.fillText("Hello World",10,50);
Demo: http://codepen.io/anon/pen/RaxwLp?editors=1011
Pad was blocked because when key is pressed acceleration is always increased, so in order to move in opposite direction first it must go to 0 which takes quite some time. I have added keyup event and when key is released acceleration is zeroed:
if(leftPressed){
acceleraton.HThrust(.01);
}else if(rightPressed){
acceleraton.HThrust(-.01);
}else{
acceleraton.Halt();
}
This is what I am trying to achieve--GRASS Animation(Desired animation)
This is where the project is standing currently --My hair animation
This is a more structurised code of the above code --My hair animation(by markE)--markE`s code of hair animation
PROBLEM:--
I am able to give movements to hairs but animation should be more like wavy grass like freeflowing.Its not very smooth now.What can be done to make the hairs flow in more natural manner.
Please provide me with a small sample if possible!!!
<canvas id="myCanvas" width="500" height="500" style="background-color: antiquewhite" ></canvas>
JAVASCRIPT
//mouse position
var x2=0;
var y2=0;
window.addEventListener("mousemove",function(){moving(event);init()},false)
//these variables define the bend in our bezier curve
var bend9=0;
var bend8=0;
var bend7=0;
var bend6=0;
var bend5=0;
var bend4=0;
var bend3=0;
var bend2=0;
var bend1=0;
//function to get the mouse cordinates
function moving(event) {
bend_value();//this function is defined below
try
{
x2 = event.touches[0].pageX;
y2 = event.touches[0].pageY;
}
catch (error)
{
try
{
x2 = event.clientX;
y2 = event.clientY;
}
catch (e)
{
}
}
try
{
event.preventDefault();
}
catch (e)
{
}
if(between(y2,204,237) && between(x2,115,272))
{
console.log("Xmove="+x2,"Ymove="+y2)
}
}
//function for declaring range of bezier curve
function between(val, min, max)
{
return val >= min && val <= max;
}
(function() {
hair = function() {
return this;
};
hair.prototype={
draw_hair:function(a,b,c,d,e,f,g,h){
var sx =136+a;//start position of curve.used in moveTo(sx,sy)
var sy =235+b;
var cp1x=136+c;//control point 1
var cp1y=222+d;
var cp2x=136+e;//control point 2
var cp2y=222+f;
var endx=136+g;//end points
var endy=210+h;
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
// context.clearRect(0, 0,500,500);
context.strokeStyle="grey";
context.lineWidth="8";
context.beginPath();
context.moveTo(sx,sy);
context.bezierCurveTo(cp1x,cp1y,cp2x,cp2y,endx,endy);
context.lineCap = 'round';
context.stroke();
// context.restore();
// context.save();
}
};
})();
//this function provides and calculate the bend on mousemove
function bend_value(){
var ref1=135;//this is ref point for hair or curve no 1
var ref2=150;//hair no 2 and so on
var ref3=165;
var ref4=180;
var ref5=195;
var ref6=210;
var ref7=225;
var ref8=240;
var ref9=255;
if(between(x2,115,270) && between(y2,205,236))
{
if(x2>=135 && x2<=145){bend1=(x2-ref1)*(2.2);}
if(x2<=135 && x2>=125){bend1=(x2-ref1)*(2.2);}
if(x2>=150 && x2<=160){bend2=(x2-ref2)*(2.2);}
if(x2<=150 && x2>=140){bend2=(x2-ref2)*(2.2);}
if(x2>=165 && x2<=175){bend3=(x2-ref3)*(2.2);}
if(x2<=165 && x2>=155){bend3=(x2-ref3)*(2.2);}
if(x2>=180 && x2<=190){bend4=(x2-ref4)*(2.2);}
if(x2<=180 && x2>=170){bend4=(x2-ref4)*(2.2);}
if(x2>=195 && x2<=205){bend5=(x2-ref5)*(2.2);}
if(x2<=195 && x2>=185){bend5=(x2-ref5)*(2.2);}
if(x2>=210 && x2<=220){bend6=(x2-ref6)*(2.2);}
if(x2<=210 && x2>=200){bend6=(x2-ref6)*(2.2);}
if(x2>=225 && x2<=235){bend7=(x2-ref7)*(2.2);}
if(x2<=225 && x2>=215){bend7=(x2-ref7)*(2.2);}
if(x2>=240 && x2<=250){bend8=(x2-ref8)*(2.2);}
if(x2<=240 && x2>=230){bend8=(x2-ref8)*(2.2);}
if(x2>=255 && x2<=265){bend9=(x2-ref9)*(2.2);}
if(x2<=255 && x2>=245){bend9=(x2-ref9)*(2.2);}
}
}
function init(){//this function draws each hair/curve
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
var clear=context.clearRect(0, 0,500,500);
var save=context.save();
// /* console.log("bend2="+bend2)
// console.log("bend3="+bend3)
// console.log("bend4="+bend4)
// console.log("bend5="+bend5)
// console.log("bend6="+bend6)
// console.log("bend7="+bend7)
// console.log("bend8="+bend8)
// console.log("bend9="+bend9)*/
hd1 = new hair();//hd1 stands for hair draw 1.this is an instance created for drawing hair no 1
clear;
hd1.draw_hair(0,0,0,0,0,0,0+bend1/2,0);//these parameters passed to function drawhair and bend is beint retrieved from function bend_value()
save;
hd2 = new hair();
clear;
hd2.draw_hair(15,0,15,0,15,0,15+bend2/2,0);
save;
hd3 = new hair();
clear;
hd3.draw_hair(30,0,30,0,30,0,30+bend3/2,0);
save;
hd4 = new hair();
clear;
hd4.draw_hair(45,0,45,0,45,0,45+bend4/2,0);
save;
hd5 = new hair();
clear;
hd5.draw_hair(60,0,60,0,60,0,60+bend5/2,0);
save;
}
window.onload = function() {
init();
disableSelection(document.body)
}
function disableSelection(target){
if (typeof target.onselectstart!="undefined") //IE
target.onselectstart=function(){return false}
else if (typeof target.style.MozUserSelect!="undefined") //Firefox
target.style.MozUserSelect="none"
else //All other ie: Opera
target.onmousedown=function(){return false}
target.style.cursor = "default"
}
Update: I'm currently adjusting the code to produce the requested result and commenting it.
(function() { // The code is encapsulated in a self invoking function to isolate the scope
"use strict";
// The following lines creates shortcuts to the constructors of the Box2D types used
var B2Vec2 = Box2D.Common.Math.b2Vec2,
B2BodyDef = Box2D.Dynamics.b2BodyDef,
B2Body = Box2D.Dynamics.b2Body,
B2FixtureDef = Box2D.Dynamics.b2FixtureDef,
B2Fixture = Box2D.Dynamics.b2Fixture,
B2World = Box2D.Dynamics.b2World,
B2PolygonShape = Box2D.Collision.Shapes.b2PolygonShape,
B2RevoluteJoint = Box2D.Dynamics.Joints.b2RevoluteJoint,
B2RevoluteJointDef = Box2D.Dynamics.Joints.b2RevoluteJointDef;
// This makes sure that there is a method to request a callback to update the graphics for next frame
window.requestAnimationFrame =
window.requestAnimationFrame || // According to the standard
window.mozRequestAnimationFrame || // For mozilla
window.webkitRequestAnimationFrame || // For webkit
window.msRequestAnimationFrame || // For ie
function (f) { window.setTimeout(function () { f(Date.now()); }, 1000/60); }; // If everthing else fails
var world = new B2World(new B2Vec2(0, -10), true), // Create a world with gravity
physicalObjects = [], // Maintain a list of the simulated objects
windInput = 0, // The input for the wind in the current frame
wind = 0, // The current wind (smoothing the input values + randomness)
STRAW_COUNT = 10, // Number of straws
GRASS_RESET_SPEED = 2, // How quick should the straw reset to its target angle
POWER_MOUSE_WIND = 120, // How much does the mouse affect the wind
POWER_RANDOM_WIND = 180; // How much does the randomness affect the wind
// GrassPart is a prototype for a piece of a straw. It has the following properties
// position: the position of the piece
// density: the density of the piece
// target: the target angle of the piece
// statik: a boolean stating if the piece is static (i.e. does not move)
function GrassPart(position, density, target, statik) {
this.width = 0.05;
this.height = 0.5;
this.target = target;
// To create a physical body in Box2D you have to setup a body definition
// and create at least one fixture.
var bdef = new B2BodyDef(), fdef = new B2FixtureDef();
// In this example we specify if the body is static or not (the grass roots
// has to be static to keep the straw in its position), and its original
// position.
bdef.type = statik? B2Body.b2_staticBody : B2Body.b2_dynamicBody;
bdef.position.SetV(position);
// The fixture of the piece is a box with a given density. The negative group index
// makes sure that the straws does not collide.
fdef.shape = new B2PolygonShape();
fdef.shape.SetAsBox(this.width/2, this.height/2);
fdef.density = density;
fdef.filter.groupIndex = -1;
// The body and fixture is created and added to the world
this.body = world.CreateBody(bdef);
this.body.CreateFixture(fdef);
}
// This method is called for every frame of animation. It strives to reset the original
// angle of the straw (the joint). The time parameter is unused here but contains the
// current time.
GrassPart.prototype.update = function (time) {
if (this.joint) {
this.joint.SetMotorSpeed(GRASS_RESET_SPEED*(this.target - this.joint.GetJointAngle()));
}
};
// The link method is used to link the pieces of the straw together using a joint
// other: the piece to link to
// torque: the strength of the joint (stiffness)
GrassPart.prototype.link = function(other, torque) {
// This is all Box2D specific. Look it up in the manual.
var jdef = new B2RevoluteJointDef();
var p = this.body.GetWorldPoint(new B2Vec2(0, 0.5)); // Get the world coordinates of where the joint
jdef.Initialize(this.body, other.body, p);
jdef.maxMotorTorque = torque;
jdef.motorSpeed = 0;
jdef.enableMotor = true;
// Add the joint to the world
this.joint = world.CreateJoint(jdef);
};
// A prototype for a straw of grass
// position: the position of the bottom of the root of the straw
function Grass(position) {
var pos = new B2Vec2(position.x, position.y);
var angle = 1.2*Math.random() - 0.6; // Randomize the target angle
// Create three pieces, the static root and to more, and place them in line.
// The second parameter is the stiffness of the joints. It controls how the straw bends.
// The third is the target angle and different angles are specified for the pieces.
this.g1 = new GrassPart(pos, 1, angle/4, true); // This is the static root
pos.Add(new B2Vec2(0, 1));
this.g2 = new GrassPart(pos, 0.75, angle);
pos.Add(new B2Vec2(0, 1));
this.g3 = new GrassPart(pos, 0.5);
// Link the pieces into a straw
this.g1.link(this.g2, 20);
this.g2.link(this.g3, 3);
// Add the pieces to the list of simulate objects
physicalObjects.push(this.g1);
physicalObjects.push(this.g2);
physicalObjects.push(this.g3);
}
Grass.prototype.draw = function (context) {
var p = new B2Vec2(0, 0.5);
var p1 = this.g1.body.GetWorldPoint(p);
var p2 = this.g2.body.GetWorldPoint(p);
var p3 = this.g3.body.GetWorldPoint(p);
context.strokeStyle = 'grey';
context.lineWidth = 0.4;
context.lineCap = 'round';
context.beginPath();
context.moveTo(p1.x, p1.y);
context.quadraticCurveTo(p2.x, p2.y, p3.x, p3.y);
context.stroke();
};
var lastX, grass = [], context = document.getElementById('canvas').getContext('2d');
function updateGraphics(time) {
window.requestAnimationFrame(updateGraphics);
wind = 0.95*wind + 0.05*(POWER_MOUSE_WIND*windInput + POWER_RANDOM_WIND*Math.random() - POWER_RANDOM_WIND/2);
windInput = 0;
world.SetGravity(new B2Vec2(wind, -10));
physicalObjects.forEach(function(obj) { if (obj.update) obj.update(time); });
world.Step(1/60, 8, 3);
world.ClearForces();
context.clearRect(0, 0, context.canvas.width, context.canvas.height);
context.save();
context.translate(context.canvas.width/2, context.canvas.height/2);
context.scale(context.canvas.width/20, -context.canvas.width/20);
grass.forEach(function (o) { o.draw(context); });
context.restore();
}
document.getElementsByTagName('body')[0].addEventListener("mousemove", function (e) {
windInput = Math.abs(lastX - e.x) < 200? 0.2*(e.x - lastX) : 0;
lastX = e.x;
});
var W = 8;
for (var i = 0; i < STRAW_COUNT; i++) {
grass.push(new Grass(new B2Vec2(W*(i/(STRAW_COUNT-1))-W/2, -1)));
}
window.requestAnimationFrame(updateGraphics);
})();
Waving grass algorithm
UPDATE
I made a reduced update to better meet what I believe is your requirements. To use mouse you just calculate the angle between the mouse point and the strain root and use that for new angle in the update.
I have incorporated a simple mouse-move sensitive approach which makes the strains "point" towards the mouse, but you can add random angles to this as deltas and so forth. Everything you need is as said in the code - adjust as needed.
New fiddle (based on previous with a few modifications):
http://jsfiddle.net/AbdiasSoftware/yEwGc/
Image showing 150 strains being simulated.
Grass simulation demo:
http://jsfiddle.net/AbdiasSoftware/5z89V/
This will generate a nice realistic looking grass field. The demo has 70 grass rendered (works best in Chrome or just lower the number for Firefox).
The code is rather simple. It consists of a main object (grassObj) which contains its geometry as well as functions to calculate the angles, segments, movements and so forth. I'll show this in detail below.
First some inits that are accessed globally by the functions:
var numOfGrass = 70, /// number of grass strains
grass,
/// get canvas context
ctx = canvas.getContext('2d'),
w = canvas.width,
h = canvas.height,
/// we use an animated image for the background
/// The image also clears the canvas for each loop call
/// I rendered the clouds in a 3D software.
img = document.createElement('img'),
ix = 0, /// background image position
iw = -1; /// used for with and initial for flag
/// load background image, use it whenever it's ready
img.onload = function() {iw = this.width}
img.src = 'http://i.imgur.com/zzjtzG7.jpg';
The heart - grassObj
The main object as mentioned above is the grassObj:
function grassObj(x, y, seg1, seg2, maxAngle) {
/// exposed properties we need for rendering
this.x = x; /// bottom position of grass
this.y = y;
this.seg1 = seg1; /// segments of grass
this.seg2 = seg2;
this.gradient = getGradient(Math.random() * 50 + 50, 100 * Math.random() + 170);
this.currentAngle; ///current angle that will be rendered
/// internals used for calculating new angle, goal, difference and speed
var counter, /// counter between 0-1 for ease-in/out
delta, /// random steps in the direction goal rel. c.angle.
angle, /// current angle, does not change until goal is reached
diff, /// diff between goal and angle
goal = getAngle();
/// internal: returns an angel between 0 and maxAngle
function getAngle() {
return maxAngle * Math.random();
}
/// ease in-out function
function easeInOut(t) {
return t < 0.5 ? 4 * t * t * t : (t-1) * (2 * t - 2) * (2 * t - 2) + 1;
}
/// sets a new goal for grass to move to. Does the main calculations
function newGoal() {
angle = goal; /// set goal as new angle when reached
this.currentAngle = angle;
goal = getAngle(); /// get new goal
diff = goal - angle; /// calc diff
counter = 0; /// reset counter
delta = (4 * Math.random() + 1) / 100;
}
/// creates a gradient for this grass to increase realism
function getGradient(min, max) {
var g = ctx.createLinearGradient(0, 0, 0, h);
g.addColorStop(1, 'rgb(0,' + parseInt(min) + ', 0)');
g.addColorStop(0, 'rgb(0,' + parseInt(max) + ', 0)');
return g;
}
/// this is called from animation loop. Counts and keeps tracks of
/// current position and calls new goal when current goal is reached
this.update = function() {
/// count from 0 to 1 with random delta value
counter += delta;
/// if counter passes 1 then goal is reached -> get new goal
if (counter > 1) {
newGoal();
return;
}
/// ease in/out function
var t = easeInOut(counter);
/// update current angle for render
this.currentAngle = angle + t * diff;
}
/// init
newGoal();
return this;
}
Grass generator
We call makeGrass to generate grass at random positions, random heights and with random segments. The function is called with number of grass to render, width and height of canvas to fill and a variation variable in percent (0 - 1 float).
The single grass consist only of four points in total. The two middle points are spread about 1/3 and 2/3 of the total height with a little variation to break pattern. The points when rendered, are smoother using a cardinal spline with full tension to make the grass look smooth.
function makeGrass(numOfGrass, width, height, hVariation) {
/// setup variables
var x, y, seg1, seg2, angle,
hf = height * hVariation, /// get variation
i = 0,
grass = []; /// array to hold the grass
/// generate grass
for(; i < numOfGrass; i++) {
x = width * Math.random(); /// random x position
y = height - hf * Math.random(); /// random height
/// break grass into 3 segments with random variation
seg1 = y / 3 + y * hVariation * Math.random() * 0.1;
seg2 = (y / 3 * 2) + y * hVariation * Math.random() * 0.1;
grass.push(new grassObj(x, y, seg1, seg2, 15 * Math.random() + 50));
}
return grass;
}
Render
The render function just loops through the objects and updates the current geometry:
function renderGrass(ctx, grass) {
/// local vars for animation
var len = grass.length,
i = 0,
gr, pos, diff, pts, x, y;
/// renders background when loaded
if (iw > -1) {
ctx.drawImage(img, ix--, 0);
if (ix < -w) {
ctx.drawImage(img, ix + iw, 0);
}
if (ix <= -iw) ix = 0;
} else {
ctx.clearRect(0, 0, w, h);
}
/// loops through the grass object and renders current state
for(; gr = grass[i]; i++) {
x = gr.x;
y = gr.y;
ctx.beginPath();
/// calculates the end-point based on length and angle
/// Angle is limited [0, 60] which we add 225 deg. to get
/// it upwards. Alter 225 to make grass lean more to a side.
pos = lineToAngle(ctx, x, h, y, gr.currentAngle + 225);
/// diff between end point and root point
diff = (pos[0] - x)
pts = [];
/// starts at bottom, goes to top middle and then back
/// down with a slight offset to make the grass
pts.push(x); /// first couple at bottom
pts.push(h);
/// first segment 1/4 of the difference
pts.push(x + (diff / 4));
pts.push(h - gr.seg1);
/// second segment 2/3 of the difference
pts.push(x + (diff / 3 * 2));
pts.push(h - gr.seg2);
pts.push(pos[0]); /// top point
pts.push(pos[1]);
/// re-use previous data, but go backward down to root again
/// with a slight offset
pts.push(x + (diff / 3 * 2) + 10);
pts.push(h - gr.seg2);
pts.push(x + (diff / 4) + 12);
pts.push(h - gr.seg1 + 10);
pts.push(x + 15); /// end couple at bottom
pts.push(h);
/// smooth points (extended context function, see demo)
ctx.curve(pts, 0.8, 5);
ctx.closePath();
/// fill grass with its gradient
ctx.fillStyle = gr.gradient;
ctx.fill();
}
}
Animate
The main loop where we animate everything:
function animate() {
/// update each grass objects
for(var i = 0;i < grass.length; i++) grass[i].update();
/// render them
renderGrass(ctx, grass);
/// loop
requestAnimationFrame(animate);
}
And that's all there is to it for this version.
Darn! Late to the party...
But LOTS of neat answers here -- I'm upvoting all !
Anyway, here's my idea:
Here's code and a Fiddle: http://jsfiddle.net/m1erickson/MJjHz/
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script src="http://code.jquery.com/jquery-1.9.1.js"></script>
<script src="http://code.jquery.com/ui/1.10.1/jquery-ui.js"></script>
<style>
body { font-family: arial; padding:15px; }
canvas { border: 1px solid red;}
input[type="text"]{width:35px;}
</style>
</head>
<body>
<p>Move mouse across hairs</p>
<canvas height="100" width="250" id="canvas"></canvas>
<script>
$(function() {
var canvas=document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var canvasOffset=$("#canvas").offset();
var offsetX=canvasOffset.left;
var offsetY=canvasOffset.top;
var cHeight=canvas.height;
var showControls=false;
var lastMouseX=0;
// preset styling CONSTANTS
var SWAY=.55; // max endpoint sway from center
var C1Y=.40; // fixed Y of cp#1
var C2SWAY=.20 // max cp#2 sway from center
var C2Y=.75; // fixed Y of cp#2
var YY=20; // max height of ellipse at top of hair
var PIPERCENT=Math.PI/100;
var hairs=[];
// create hairs
var newHairX=40;
var hairCount=20;
for(var i=0;i<hairCount;i++){
var randomLength=50+parseInt(Math.random()*5);
addHair(newHairX+(i*8),randomLength);
}
function addHair(x,length){
hairs.push({
x:x,
length:length,
left:0,
right:0,
top:0,
s:{x:0,y:0},
c1:{x:0,y:0},
c2:{x:0,y:0},
e:{x:0,y:0},
isInMotion:false,
currentX:0
});
}
for(var i=0;i<hairs.length;i++){
var h=hairs[i];
setHairPointsFixed(h);
setHairPointsPct(h,50);
draw(h);
}
function setHairPointsFixed(h){
h.s.x = h.x;
h.s.y = cHeight;
h.c1.x = h.x;
h.c1.y = cHeight-h.length*C1Y;
h.c2.y = cHeight-h.length*C2Y;
h.top = cHeight-h.length;
h.left = h.x-h.length*SWAY;
h.right = h.x+h.length*SWAY;
}
function setHairPointsPct(h,pct){
// endpoint
var a=Math.PI+PIPERCENT*pct;
h.e.x = h.x - ((h.length*SWAY)*Math.cos(a));
h.e.y = h.top + (YY*Math.sin(a));
// controlpoint#2
h.c2.x = h.x + h.length*(C2SWAY*2*pct/100-C2SWAY);
}
//////////////////////////////
function handleMouseMove(e){
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
// draw this frame based on mouse moves
ctx.clearRect(0,0,canvas.width,canvas.height);
for(var i=0;i<hairs.length;i++){
hairMoves(hairs[i],mouseX,mouseY);
}
lastMouseX=mouseX;
}
$("#canvas").mousemove(function(e){handleMouseMove(e);});
function hairMoves(h,mouseX,mouseY){
// No hair movement if not touching hair
if(mouseY<cHeight-h.length-YY){
if(h.isInMotion){
h.isInMotion=false;
setHairPointsPct(h,50);
}
draw(h);
return;
}
// No hair movement if too deep in hair
if(mouseY>h.c1.y){
draw(h);
return;
}
//
var pct=50;
if(mouseX>=h.left && mouseX<=h.right){
if(h.isInMotion){
var pct=-(mouseX-h.right)/(h.right-h.left)*100;
setHairPointsPct(h,pct);
draw(h);
}else{
// if hair is at rest
// but mouse has just contacted hair
// set hair in motion
if( (lastMouseX<=h.x && mouseX>=h.x )
||(lastMouseX>=h.x && mouseX<=h.x )
){
h.isInMotion=true;
var pct=-(mouseX-h.right)/(h.right-h.left)*100;
}
setHairPointsPct(h,pct);
draw(h);
}
}else{
if(h.isInMotion){
h.isInMotion=false;
setHairPointsPct(h,50);
};
draw(h);
}
}
function dot(pt,color){
ctx.beginPath();
ctx.arc(pt.x,pt.y,5,0,Math.PI*2,false);
ctx.closePath();
ctx.fillStyle=color;
ctx.fill();
}
function draw(h){
ctx.beginPath();
ctx.moveTo(h.s.x,h.s.y);
ctx.bezierCurveTo(h.c1.x,h.c1.y,h.c2.x,h.c2.y,h.e.x,h.e.y);
ctx.strokeStyle="orange";
ctx.lineWidth=3;
ctx.stroke();
if(showControls){
dot(h.s,"green");
dot(h.c1,"red");
dot(h.c2,"blue");
dot(h.e,"purple");
ctx.beginPath();
ctx.rect(h.left,h.top-YY,(h.right-h.left),h.length*(1-C1Y)+YY)
ctx.lineWidth=1;
ctx.strokeStyle="lightgray";
ctx.stroke();
}
}
});
</script>
</body>
</html>
Here is a simple hair simulation that seems to be what you are looking for. The basic idea is to draw a bezier curve (in this case I use two curves to provide thickness for the hair). The curve will have a base, a bending point, and a tip. I set the bending point halfway up the hair. The tip of the hair will rotate about the axis of the base of the hair in response to mouse movement.
Place this code in a script tag below the canvas element declaration.
function Point(x, y) {
this.x = x;
this.y = y;
}
function Hair( ) {
this.height = 100; // hair height
this.baseWidth = 3; // hair base width.
this.thickness = 1.5; // hair thickness
this.points = {};
this.points.base1 = new Point(Math.random()*canvas.width, canvas.height);
// The point at which the hair will bend. I set it to the middle of the hair, but you can adjust this.
this.points.bendPoint1 = new Point(this.points.base1.x-this.thickness, this.points.base1.y - this.height / 2)
this.points.bendPoint2 = new Point(this.points.bendPoint1.x, this.points.bendPoint1.y-this.thickness); // complement of bendPoint1 - we use this because the hair has thickness
this.points.base2 = new Point(this.points.base1.x + this.baseWidth, this.points.base1.y) // complement of base1 - we use this because the hair has thickness
}
Hair.prototype.paint = function(mouseX, mouseY, direction) {
ctx.save();
// rotate the the tip of the hair
var tipRotationAngle = Math.atan(Math.abs(this.points.base1.y - mouseY)/Math.abs(this.points.base1.x - mouseX));
// if the mouse is on the other side of the hair, adjust the angle
if (mouseX < this.points.base1.x) {
tipRotationAngle = Math.PI - tipRotationAngle;
}
// if the mouse isn't close enough to the hair, it shouldn't affect the hair
if (mouseX < this.points.base1.x - this.height/2 || mouseX > this.points.base1.x + this.height/2 || mouseY < this.points.base1.y - this.height || mouseY > this.points.base1.y) {
tipRotationAngle = Math.PI/2; // 90 degrees, which means the hair is straight
}
// Use the direction of the mouse to as a lazy way to simulate the direction the hair should bend.
// Note that in real life, the direction that the hair should bend has nothing to do with the direction of motion. It actually depends on which side of the hair the force is being applied.
// Figuring out which side of the hair the force is being applied is a little tricky, so I took this shortcut.
// If you run your finger along a comb quickly, this approximation will work. However if you are in the middle of the comb and slowly change direction, you will notice that the force is still applied in the opposite direction of motion as you slowly back off the set of tines.
if ((mouseX < this.points.base1.x && direction == 'right') || (mouseX > this.points.base1.x && direction == 'left')) {
tipRotationAngle = Math.PI/2; // 90 degrees, which means the hair is straight
}
var tipPoint = new Point(this.points.base1.x + this.baseWidth + this.height*Math.cos(tipRotationAngle), this.points.base1.y - this.height*Math.sin(tipRotationAngle));
ctx.beginPath();
ctx.moveTo(this.points.base1.x, this.points.base1.y); // start at the base
ctx.bezierCurveTo(this.points.base1.x, this.points.base1.y, this.points.bendPoint1.x, this.points.bendPoint1.y, tipPoint.x, tipPoint.y); // draw a curve to the tip of the hair
ctx.bezierCurveTo(tipPoint.x, tipPoint.y, this.points.bendPoint2.x, this.points.bendPoint2.y, this.points.base2.x, this.points.base2.y); // draw a curve back down to the base using the complement points since the hair has thickness.
ctx.closePath(); // complete the path so we have a shape that we can fill with color
ctx.fillStyle='rgb(0,0,0)';
ctx.fill();
ctx.restore();
}
// I used global variables to keep the example simple, but it is generally best to avoid using global variables
window.canvas = document.getElementById('myCanvas');
window.ctx = canvas.getContext('2d');
ctx.fillStyle = 'rgb(200,255,255)'; // background color
window.hair = [];
window.prevClientX = 0;
for (var i = 0; i < 100; i++) {
hair.push(new Hair());
}
// initial draw
ctx.fillRect(0,0,canvas.width,canvas.height); // clear canvas
for (var i = 0; i < hair.length; i++) {
hair[i].paint(0, 0, 'right');
}
window.onmousemove = function(e) {
ctx.fillRect(0,0,canvas.width,canvas.height); // clear canvas
for (var i = 0; i < hair.length; i++) {
hair[i].paint(e.clientX, e.clientY, e.clientX > window.prevClientX ? 'right' : 'left');
}
window.prevClientX = e.clientX;
}
Made this some time ago, might be useful to some people. Just adjust the variables at the beginning of the code with the values that fits your wishes:
...
Mheight = 1;
height = 33;
width = 17;
distance = 10;
randomness = 14;
angle = Math.PI / 2;
...
Also on http://lucasm0ta.github.io/JsGrass/
I'm trying to drag an image around on my canvas but in doing so I have an issue where once the image is in negative coordinates I get a condition where its
mouseX - negativeImageCoords // 200 - minus 210 = 410
making my image jump around like a popcorn kitten on the canvas, not the desired effect.
Here is my code and I'm hoping it's something stupid and I can put this down to being tired..
function (e) {
var
// The mouse x and y positions
mx = e.offsetX,
my = e.offsetY,
// The last known position
lx = cache.lx, // These are from a JSON object
ly = cache.ly;
// The temporary image
var img = $('#loadedImage');
// Get the image context
var canvas_context = this.mask();
cache.lx = (mx - lx);
cache.ly = (my - ly);
console.log(mx, lx);
console.log(my, ly);
// Redraw
canvas_context.drawImage(img.get(0), cache.lx, cache.ly, img.width(), img.height());
}
here is the mask function (included in case it is the perpetrator..
function () {
var mask_name = 'circle';
var context = ctx.context();
var mask;
var isSameMask = false;
var composition = 'lighter';
// Add a check to see if it's the same mask
if (cache.mask && cache.mask.src) {
if (cache.mask.src !== 'images/masks/' + mask_name + '.png') {
isSameMask = false;
}
}
// If we don't have a cached mask, load it and cache it
if (!cache.mask && !isSameMask) {
// Create a new mask
mask = new Image;
// Draw when its loaded
mask.onload = function () {
//ctx.clear();
context.drawImage(this, 0, 0);
context.globalCompositeOperation = composition;
};
mask.src = 'images/masks/' + mask_name + '.png';
// Set the cache as this new mask
cache.mask = mask;
imageEvents.size(0);
} else {
ctx.clear();
// It's cached, so just redraw it
context.drawImage(cache.mask, 0, 0);
context.globalCompositeOperation = composition;
}
return context;
}
Why is the image jumping around?
It has to be noted that I have thrown this together for an appjs project, any help/advice from you all is greatly appreciated.
Right, managed to get this working. The fix was updating the cached image positions on mousedown and just adding the cached positions to the mouse positions. Here is the code:
function drag (e) { // :void
var
// The mouse x and y positions
mx = e.offsetX,
my = e.offsetY,
// The last known position
lx = mx+cache.lx,
ly = my+cache.ly;
// The temporary image
var img = $('#loadedImage');
// Get the image context
var canvas_context = this.mask();
cache.ix = lx;
cache.iy = ly;
// Redraw
canvas_context.drawImage(img.get(0), lx, ly, img.width(), img.height());
textEvents.draw();
}
And my down events
cache.ix = 0;
cache.iy = 0;
// Listen for a mousedown or touchstart event
canvas.on('mousedown touchstart', function (e) {
cache.lx = cache.ix - e.offsetX;
cache.ly = cache.iy - e.offsetY;
// Add a move listener
canvas.on('mousemove touchmove', function (e) {
that.drag.call(that, e);
});
});
It's hard to provide an answer without seeing the code in action but could it be those conditions you specify, e.g.:
if (lx < 0) {
cache.lx = (mx + lx);
} else {
cache.lx = (mx - lx);
}
Surely you don't want to change the sums if lx is less or more than 0. Just let the maths do its job. Mathematically:
mx + -1 is the same as mx - 1
mx + +1 is the same as mx + 1
mx - -1 is the same as mx + 1 [double negative]
That would be why '200 - minus 210 = 410'; that's actually correct.
EDIT
The variable lx is the cached (therefore old) position; mx is the new position.
Therefore lx - mx will return the difference between the cached and the new position, which I think (if I understand you correctly) is what you want to move your image by a certain amount. Same for ly - my.
When it comes to caching the new mouse positions, surely you just want to cache the current ones, e.g.
cache.lx = mx; // current position cached for future reference
Caching the difference or a summation will just add to the confusion (again, if I've understood what you're trying to do).