Intel Animation for Java* Package Tutorial

Lesson 3: Moving Sprites

This applet shows an Elvis sprite that can be moved. Clicking the buttons cause Elvis to move left and right. When Elvis reaches the edge of the screen, the Floor and Background move.

The following needs to be done to move a sprite:

1. Get the position of the sprite (see Notes on Coordinate System below)

Point3D pos = sprite.getPosition(sprite);

2. Adjust the position

pos.x = pos.x + DELTA_X;

3. Set the position of the sprite

sprite.setPosition(pos);

4. Draw the repositioned sprite on the screen

animcanvas.repaint();

Notes on Coordinate System
When you call getPosition or setPosition, the Point3D describes the location of the top, left corner of the sprite on the surface. This Point3D is on the coordinate system of the surface.

Coordinate systems in Intel Animation for Java have the following characteristics:

• the origin is at the top left corner
• the x coordinate increases toward the right
• the y coordinate increases downward
• the z coordinate represents depth. Sprites that have a lower z are drawn last, or over the sprites with a higher z. In this applet, Elvis has z = 200 and the floor has a z = 300, so Elvis is drawn after the floor (Elvis appears to have been drawn over the floor).
• x and y can have negative values. z CANNOT have a negative value.

View Source

This page was last updated on Feb 11th, 1997.

Legal Stuff