gravity Property in HTML 5

>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<style>
canvas {
border:1px solid #d3d3d3;
background-color: #f1f1f1;
}
style>
head>
<body onload="startGame()">
<script>
var myGamePiece;
var myObstacles = [];
var myScore;
function startGame() {
myGamePiece = new component(30, 30, "red", 10, 120);
myGamePiece.gravity = 0.05;
myScore = new component("30px", "Consolas", "black", 280, 40, "text");
myGameArea.start();
}
var myGameArea = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 480;
this.canvas.height = 270;
thisthis.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.frameNo = 0;
updateGameArea();
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y, type) {
this.type = type;
this.score = 0;
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.gravity = 0;
this.gravitySpeed = 0;
this.update = function() {
ctx = myGameArea.context;
if (this.type == "text") {
ctx.font = this.width + " " + this.height;
ctx.fillStyle = color;
ctx.fillText(this.text, this.x, this.y);
} else {
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
this.newPos = function() {
this.gravitySpeed += this.gravity;
this.x += this.speedX;
this.y += this.speedY + this.gravitySpeed;
this.hitBottom();
}
this.hitBottom = function() {
var rockbottom = myGameArea.canvas.height - this.height;
if (this.y > rockbottom) {
this.y = rockbottom;
this.gravitySpeed = 0;
}
}
this.crashWith = function(otherobj) {
var myleft = this.x;
var myright = this.x + (this.width);
var mytop = this.y;
var mybottom = this.y + (this.height);
var otherleft = otherobj.x;
var otherright = otherobj.x + (otherobj.width);
var othertop = otherobj.y;
var otherbottom = otherobj.y + (otherobj.height);
var crash = true;
if ((mybottom < othertop) || (mytop > otherbottom) || (myright < otherleft) || (myleft > otherright)) {
crash = false;
}
return crash;
}
}
function updateGameArea() {
var x, height, gap, minHeight, maxHeight, minGap, maxGap;
for (i = 0; i < myObstacles.length; i += 1) {
if (myGamePiece.crashWith(myObstacles[i])) {
return;
}
}
myGameArea.clear();
myGameArea.frameNo += 1;
if (myGameArea.frameNo == 1 || everyinterval(150)) {
x = myGameArea.canvas.width;
minHeight = 20;
maxHeight = 200;
height = Math.floor(Math.random()*(maxHeight-minHeight+1)+minHeight);
minGap = 50;
maxGap = 200;
gap = Math.floor(Math.random()*(maxGap-minGap+1)+minGap);
myObstacles.push(new component(10, height, "green", x, 0));
myObstacles.push(new component(10, x - height - gap, "green", x, height + gap));
}
for (i = 0; i < myObstacles.length; i += 1) {
myObstacles[i].x += -1;
myObstacles[i].update();
}
myScore.text="SCORE: " + myGameArea.frameNo;
myScore.update();
myGamePiece.newPos();
myGamePiece.update();
}
function everyinterval(n) {
if ((myGameArea.frameNo / n) % 1 == 0) {return true;}
return false;
}
function accelerate(n) {
if (!myGameArea.interval) {myGameArea.interval = setInterval(updateGameArea, 20);}
myGamePiece.gravity = n;
}
script>
<br>
<button onmousedown="accelerate(-0.2)" onmouseup="accelerate(0.05)">ACCELERATEbutton>
<p>Click the ACCELERATE button to start the gamep>
<p>How long can you stay alive? Use the ACCELERATE button to stay in the air..p>
body>
html>

>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<style>
canvas {
border:1px solid #d3d3d3;
background-color: #f1f1f1;
}
style>
head>
<body onload="startGame()">
<script>
var myGamePiece;
function startGame() {
myGamePiece = new component(30, 30, "red", 80, 75);
myGameArea.start();
}
var myGameArea = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 480;
this.canvas.height = 270;
thisthis.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
},
stop : function() {
clearInterval(this.interval);
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y, type) {
this.type = type;
this.width = width;
this.height = height;
this.x = x;
this.y = y;
this.speedX = 0;
this.speedY = 0;
this.gravity = 0.05;
this.gravitySpeed = 0;
this.update = function() {
ctx = myGameArea.context;
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
this.newPos = function() {
this.gravitySpeed += this.gravity;
this.x += this.speedX;
this.y += this.speedY + this.gravitySpeed;
}
}
function updateGameArea() {
myGameArea.clear();
myGamePiece.newPos();
myGamePiece.update();
}
script>
<p>Gravity makes the red square fall to the ground and beyond.p>
body>
html>

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Bidyasagar Mishra7y ago
Accepted answer
1. >
2. <html>
3. <head>
4. <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
5. <style>
6. canvas {
7. border:1px solid #d3d3d3;
8. background-color: #f1f1f1;
9. }
10. style>
11. head>
12. <body onload="startGame()">
13. <script>
15. var myGamePiece;
16. var myObstacles = [];
17. var myScore;
19. function startGame() {
20. myGamePiece = new component(30, 30, "red", 10, 120);
21. myGamePiece.gravity = 0.05;
22. myScore = new component("30px", "Consolas", "black", 280, 40, "text");
23. myGameArea.start();
24. }
26. var myGameArea = {
27. canvas : document.createElement("canvas"),
28. start : function() {
29. this.canvas.width = 480;
30. this.canvas.height = 270;
31. thisthis.context = this.canvas.getContext("2d");
32. document.body.insertBefore(this.canvas, document.body.childNodes[0]);
33. this.frameNo = 0;
34. updateGameArea();
35. },
36. clear : function() {
37. this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
38. }
39. }
41. function component(width, height, color, x, y, type) {
42. this.type = type;
43. this.score = 0;
44. this.width = width;
45. this.height = height;
46. this.speedX = 0;
47. this.speedY = 0;
48. this.x = x;
49. this.y = y;
50. this.gravity = 0;
51. this.gravitySpeed = 0;
52. this.update = function() {
53. ctx = myGameArea.context;
54. if (this.type == "text") {
55. ctx.font = this.width + " " + this.height;
56. ctx.fillStyle = color;
57. ctx.fillText(this.text, this.x, this.y);
58. } else {
59. ctx.fillStyle = color;
60. ctx.fillRect(this.x, this.y, this.width, this.height);
61. }
62. }
63. this.newPos = function() {
64. this.gravitySpeed += this.gravity;
65. this.x += this.speedX;
66. this.y += this.speedY + this.gravitySpeed;
67. this.hitBottom();
68. }
69. this.hitBottom = function() {
70. var rockbottom = myGameArea.canvas.height - this.height;
71. if (this.y > rockbottom) {
72. this.y = rockbottom;
73. this.gravitySpeed = 0;
74. }
75. }
76. this.crashWith = function(otherobj) {
77. var myleft = this.x;
78. var myright = this.x + (this.width);
79. var mytop = this.y;
80. var mybottom = this.y + (this.height);
81. var otherleft = otherobj.x;
82. var otherright = otherobj.x + (otherobj.width);
83. var othertop = otherobj.y;
84. var otherbottom = otherobj.y + (otherobj.height);
85. var crash = true;
86. if ((mybottom < othertop) || (mytop > otherbottom) || (myright < otherleft) || (myleft > otherright)) {
87. crash = false;
88. }
89. return crash;
90. }
91. }
93. function updateGameArea() {
94. var x, height, gap, minHeight, maxHeight, minGap, maxGap;
95. for (i = 0; i < myObstacles.length; i += 1) {
96. if (myGamePiece.crashWith(myObstacles[i])) {
97. return;
98. }
99. }
100. myGameArea.clear();
101. myGameArea.frameNo += 1;
102. if (myGameArea.frameNo == 1 || everyinterval(150)) {
103. x = myGameArea.canvas.width;
104. minHeight = 20;
105. maxHeight = 200;
106. height = Math.floor(Math.random()*(maxHeight-minHeight+1)+minHeight);
107. minGap = 50;
108. maxGap = 200;
109. gap = Math.floor(Math.random()*(maxGap-minGap+1)+minGap);
110. myObstacles.push(new component(10, height, "green", x, 0));
111. myObstacles.push(new component(10, x - height - gap, "green", x, height + gap));
112. }
113. for (i = 0; i < myObstacles.length; i += 1) {
114. myObstacles[i].x += -1;
115. myObstacles[i].update();
116. }
117. myScore.text="SCORE: " + myGameArea.frameNo;
118. myScore.update();
119. myGamePiece.newPos();
120. myGamePiece.update();
121. }
123. function everyinterval(n) {
124. if ((myGameArea.frameNo / n) % 1 == 0) {return true;}
125. return false;
126. }
128. function accelerate(n) {
129. if (!myGameArea.interval) {myGameArea.interval = setInterval(updateGameArea, 20);}
131. myGamePiece.gravity = n;
132. }
133. script>
134. <br>
135. <button onmousedown="accelerate(-0.2)" onmouseup="accelerate(0.05)">ACCELERATEbutton>
136. <p>Click the ACCELERATE button to start the gamep>
137. <p>How long can you stay alive? Use the ACCELERATE button to stay in the air..p>
138. body>
139. html>