A Ball In A Box - Revision history

121.74.244.196 at 09:29, 3 February 2012

2012-02-03T09:29:49Z

Lerc at 19:22, 2 February 2012

2012-02-02T19:22:05Z

Lerc at 09:41, 30 January 2012

2012-01-30T09:41:12Z

Lerc at 09:22, 30 January 2012

2012-01-30T09:22:42Z

Lerc: Created page with " var cx=320; //cx,cy is the position of the ball var cy=240; // 320,240 is the starting position var dx=1; //dx is difference between the current x position a..."

2012-01-30T05:58:10Z

Created page with " <edcode> var cx=320; //cx,cy is the position of the ball var cy=240; // 320,240 is the starting position var dx=1; //dx is difference between the current x position a..."

New page

<edcode>
var cx=320; //cx,cy is the position of the ball
var cy=240; // 320,240 is the starting position

var dx=1; //dx is difference between the current x position and the next x position
var dy=-1; //dy is difference between the current x position and the next y position

var boxTop=130; //the top left corner of the box is 130,200
var boxLeft=120;

var boxWidth=400;
var boxHeight=300;

var boxBottom=boxTop+boxHeight; //The bottom right corner of the box can be calculated by adding the width and height to the left and top values
var boxRight=boxLeft+boxWidth;

function move() {

//adding the difference moves the ball
cx+=dx;
cy+=dy;

//check to see if cx has crossed the left or right edges of the box
// and if cy has crossed the top or bottom edges of the box
if (cx<boxLeft) dx=1;
if (cy<boxTop) dy=1;
if (cx>boxRight) dx=-1;
if (cy>boxBottom) dy=-1;

}

function draw() {
clear();

//draw the box
drawRectangle(boxLeft,boxTop,boxWidth,boxHeight);

//draw the ball
fillCircle(cx,cy,4);
}

run(move,draw);

</edcode>

@@ Line 19: / Line 19: @@
 var dx=3;    //dx is difference between the current x position and the next x position
-var dy=-3;   //dy is difference between the current x position and the next y position
+var dy=-3;   //dy is difference between the current y position and the next y position
 var boxTop=130;  //the top left corner of the box is 130,120

@@ Line 15: / Line 15: @@
 Think about what might happen when you run it, then run the program to see if you guessed right.
-<edcode>
+<edcode>var cx=320;  //cx,cy is the position of the ball
 var cx=320;  //cx,cy is the position of the ball
 var cy=240;  // 320,240 is the starting position
@@ Line 37: / Line 36: @@
    //check to see if cx has crossed the left or right edges of the box
    if (cx<boxLeft) dx=3;
    if (cx>boxRight) dx=-3;
    if (cy>boxBottom) dy=-3;
+}

@@ Line 12: / Line 12: @@
 Try adding the line
-     dy+=0.03;
+     dy+=0.1;
 Think about what might happen when you run it, then run the program to see if you guessed right.
@@ Line 19: / Line 19: @@
 var cy=240;  // 320,240 is the starting position
-var dx=1;    //dx is difference between the current x position and the next x position
+var dx=3;    //dx is difference between the current x position and the next x position
-var dy=-1;   //dy is difference between the current x position and the next y position
+var dy=-3;   //dy is difference between the current x position and the next y position
 var boxTop=130;  //the top left corner of the box is 130,120
@@ Line 38: / Line 38: @@
    //check to see if cx has crossed the left or right edges of the box
    //         and if cy has crossed the top or bottom edges of the box
-   if (cx<boxLeft) dx=1;
+   if (cx<boxLeft) dx=3;
-   if (cy<boxTop) dy=1;
+   if (cy<boxTop) dy=3;
-   if (cx>boxRight) dx=-1;
+   if (cx>boxRight) dx=-3;
-   if (cy>boxBottom) dy=-1;
+   if (cy>boxBottom) dy=-3;
-−
+}
@@ Line 54: / Line 53: @@
    setColour('red');
    drawRectangle(boxLeft,boxTop,boxWidth,boxHeight);
+}
 run(move,draw);
 </edcode>

@@ Line 1: / Line 1: @@
 <edcode>
@@ Line 8: / Line 22: @@
 var dy=-1;   //dy is difference between the current x position and the next y position
-var boxTop=130;  //the top left corner of the box is 130,200
+var boxTop=130;  //the top left corner of the box is 130,120
 var boxLeft=120;
@@ Line 18: / Line 32: @@
 function move() {
    //adding the difference moves the ball
    cx+=dx;
    cy+=dy;
    //check to see if cx has crossed the left or right edges of the box
@@ Line 35: / Line 47: @@
 function draw() {
    clear();
    //draw the box
    drawRectangle(boxLeft,boxTop,boxWidth,boxHeight);
+}
 run(move,draw);
 </edcode>