Bits & Bytes

In this example, I create a 3D box with a ball bouncing around inside it. To do this, I create an animation using the ENTER_FRAME event that I used in the previous animation. The entire program is below at the end of this post.

The first line of code sets the callback for each frame of animation via a call to addEventListener() with ENTER_FRAME as the event and the function NextFrame() as the callback. After this, we use the stage’s graphics object to paint the entire screen black; this will be the background.

The next four sections of code each draw a rectangle in various shades of red and rotate them to make them to be perpendicular to the view. These are the four sides of our box. They are assigned a z-value of 25 to move them slightly away from the view plane at z = 0. Finally, the back to the box is created at z = 325 with a “XoaX.net” logo Bitmap. The dimensions of the box are 320x240x300.

After the walls of the box are created, we have three sets of variables for each dimension of movement for the ball inside the box. After this, we have Bitmap that represents the ball. This ball will be moved around by our animation callback function. Lastly, we have the callback function, which reflects the ball in each coordinate, similar to what we did in the last animation with the x-coordinate. Using these reflections, we get a ball that bounces around the box as we see in window above. Note that the projection is created via the default perspective projection, which we have not discussed yet.

addEventListener(Event.ENTER_FRAME, NextFrame);

// Paint the stage black 
var uiColorBack:uint = 0x00000000;
graphics.beginFill(uiColorBack);
    graphics.drawRect(0, 0, 320, 240);
graphics.endFill();

// Top
// Create rect for sprite and add to stage
var qTop:Sprite = new Sprite();
var uiColor:uint = 0x00900000;
qTop.graphics.beginFill(uiColor);
    qTop.graphics.drawRect(0, 0, 320, 300);
qTop.graphics.endFill();
qTop.rotationX = 90;
qTop.z = 25;
addChild(qTop);

// Left
var qLeft:Sprite = new Sprite();
var uiColor2:uint = 0x00B00000;
qLeft.graphics.beginFill(uiColor2);
    qLeft.graphics.drawRect(0, 0, 300, 240);
qLeft.graphics.endFill();
qLeft.rotationY = -90;
qLeft.z = 25;
addChild(qLeft);

// Right
var qRight:Sprite = new Sprite();
var uiColor3:uint = 0x00D00000;
qRight.graphics.beginFill(uiColor3);
    qRight.graphics.drawRect(0, 0, 300, 240);
qRight.graphics.endFill();
qRight.rotationY = -90;
qRight.x = 320;
qRight.z = 25;
addChild(qRight);

// Bottom
var qBottom:Sprite = new Sprite();
var uiColor4:uint = 0x00F00000;
qBottom.graphics.beginFill(uiColor4);
    qBottom.graphics.drawRect(0, 0, 320, 300);
qBottom.graphics.endFill();
qBottom.rotationX = 90;
qBottom.y = 240;
qBottom.z = 25;
addChild(qBottom);

// Back
// Use a logo image to create a bitmap
var qLogo:Bitmap = new Bitmap(new Logo(320, 240), "never", true);
qLogo.z = 325;
addChild(qLogo);

// Variables for motion control
var uiX:uint = 0;
var uiDeltaX:uint = 4;
var kuiMaxX:uint = 260;

var uiY:uint = 0;
var uiDeltaY:uint = 3;
var kuiMaxY:uint = 180;

var uiZ:uint = 0;
var uiDeltaZ:uint = 3;
var kuiMaxZ:uint = 240;

// Use a ball image to create a bitmap
var qBall:Bitmap = new Bitmap(new Ball(60, 60), "never", true);
addChild(qBall);

// Animation callback
function NextFrame(e:Event) : void {
	uiX = ((uiX + uiDeltaX) % (kuiMaxX + 1));
	qBall.x = uiX;
	if (uiX == kuiMaxX || uiX == 0) {
		uiDeltaX = (kuiMaxX - uiDeltaX);
	}
	
	uiY = ((uiY + uiDeltaY) % (kuiMaxY + 1));
	qBall.y = uiY;
	if (uiY == kuiMaxY || uiY == 0) {
		uiDeltaY = (kuiMaxY - uiDeltaY);
	}
	
	uiZ = ((uiZ + uiDeltaZ) % (kuiMaxZ + 1));
	qBall.z = uiZ + 30 + 25;
	if (uiZ == kuiMaxZ || uiZ == 0) {
		uiDeltaZ = (kuiMaxZ - uiDeltaZ);
	}
}