I have a stick figure drawing that i've created that i'd like to animate every time the right arrow key is pressed. I understand that I cannot literally move the object, but I can erase and continually redraw the image. However my implementation is probably way off. Any help would be well appreciated.
$(document).ready(function(e){
var canvas = document.getElementById("drawCanvas"),
context = canvas.getContext('2d'),
width = canvas.width,
height = canvas.height,
head = new Array(200, 200, 10,0, 2*Math.PI) ,
body = new Array(195, 210, 178, 250) ,
leftArm = new Array(192,215,200,230,210,230),
rightArm = new Array(192,215,178 ,222,178,230),
leftLeg = new Array(178, 250,190,260,185,275,192, 275 ),
rightLeg= new Array(178, 250, 168, 260, 155, 262,153, 268 ) ;
// board for game
function board(){
context.fillStyle="#FFF";
context.fillStyle="#FFF";
context.fill();
context.strokeStyle="#000";
context.strokeRect(0,0,width,height);
}
//costume #1
function costume1(){
context.beginPath();
//head
context.arc(head[0], head[1], head[2],head[3], head[4]);
//body
context.moveTo(body[0],body[1]);
context.lineTo(body[2],body[3]);
//right arm
context.moveTo(rightArm[0],rightArm[1]);
context.lineTo(rightArm[2] ,rightArm[3]);
context.lineTo(rightArm[4], rightArm[5]);
//left arm
context.moveTo(leftArm[0], leftArm[1]);
context.lineTo(leftArm[2], leftArm[3]);
context.lineTo(leftArm[4], leftArm[5]);
//left leg
context.moveTo(leftLeg[0], leftLeg[1]);
context.lineTo(leftLeg[2],leftLeg[3]);
context.lineTo(leftLeg[4] , leftLeg[5]);
context.lineTo(leftLeg[6], leftLeg[7]);
//right leg
context.moveTo(rightLeg[0], rightLeg[1]);
context.lineTo(rightLeg[2], rightLeg[3]);
context.lineTo(rightLeg[4], rightLeg[5]);
context.lineTo(rightLeg[6], rightLeg[7]);
context.stroke();
}
//costume #2
function costume2(){
context.arc(head[0], head[1], head[2],head[3], head[4]);
//body
context.moveTo(body[0],body[1]);
context.lineTo(body[2],body[3]);
//right arm
context.moveTo(rightArm[0],rightArm[1]);
context.lineTo(rightArm[2] + 5 ,rightArm[3]);
context.lineTo(rightArm[4] + 5 , rightArm[5]);
//left arm
context.moveTo(leftArm[0] , leftArm[1] );
context.lineTo(leftArm[2] - 5 , leftArm[3] );
context.lineTo(leftArm[4] - 10, leftArm[5] );
//left leg
context.moveTo(leftLeg[0] , leftLeg[1]);
context.lineTo(leftLeg[2] - 10 ,leftLeg[3]);
context.lineTo(leftLeg[4] - 20, leftLeg[5]);
context.lineTo(leftLeg[6] - 20, leftLeg[7]);
//right leg
context.moveTo(rightLeg[0], rightLeg[1]);
context.lineTo(rightLeg[2] + 15 , rightLeg[3] );
context.lineTo(rightLeg[4] + 30 , rightLeg[5]);
context.lineTo(rightLeg[6] +10, rightLeg[7]);
context.stroke();
}
function clear(){
context.clearRect(0,0, canvas.width, canvas.height);
}
var handle = true;
board();
///move Character
function check(e) {
var code = e.keyCode;
//Up arrow pressed
if (code == 39 && handle == true) {
clear();
board();
costume2();
handle = false;
}
else if(code == 39 && handle == false) {
clear();
board();
costume1();
handle = true;
}
}
window.addEventListener('keydown',check,false);
});
I would recommend you use the window.requestAnimationFrame() to redraw the screen. This will incrementally redraw the screen for every frame of animation. For example:
$(function(){
var context = document.getElementById('myCanvas').getContext('2d');
//initialize
window.requestAnimationFrame(draw);
function draw(){
context.clearRect(0,0,800,600); // clear canvas
// draw the current frame
// animate the next frame
window.requestAnimationFrame(draw);
}});
Use canvas transformations to move your stickman around the canvas.
In particular, context.translate(50,75)
will move your stickman 50px rightward and 75px downward and importantly(!) , you don't have to change any of your stickman coordinates -- canvas handles that completely for you.
Transformations will also help you articulate the arms, legs, etc of your stickman. You can use a combination of translate( rotationPointX, rotationPointY)
and rotate(angle)
to rotate an extremity by angle
around its joint located at [rotationPointX, rotationPointY]
.
Example moving the stickman:
function drawStickman(changeInX,changeInY){
context.clearRect(0,0,canvas.width,canvas.height);
context.translate(changeInX,changeInY);
// draw your stickman -- no change in coordinates are needed
context.translate(-changeInX,-changeInY);
}
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