Learning Processing: A Beginner's Guide to Programming Images ...

230 Learning Processing
Example 14-2: Multiple translations
void setup() {
size(200,200);
smooth();
}
void draw() {
background(255);
stroke(0);
fill(175);
// Grab mouse coordinates, constrained to window
int mx = constrain(mouseX,0,width);
int my = constrain(mouseY,0,height);
// Translate to the mouse location
translate(mx,my);
ellipse(0,0,8,8);
// Translate 100 pixels to the right
translate(100,0);
ellipse(0,0,8,8);
// Translate 100 pixels down
translate(0,100);
ellipse(0,0,8,8);
// Translate 100 pixels left
translate(–100,0);
ellipse(0,0,8,8);
}
Now that we understand how translate( ) works, we can return to the original problem of specifying 3D
coordinates. translate( ) , unlike rect( ), ellipse( ) , and other shape functions, can accept a third argument for
a Z coordinate.
// Translation along the z-axis
translate(0,0,50);
rectMode(CENTER);
rect(100,100,8,8);
Th e above code translates 50 units along the Z -axis, and then draws a rectangle at (100,100). While the
above is technically correct, when using translate( ) , it is a good habit to specify the ( x , y ) location as part
of the translation, that is:
// Translation along the z-axis II
translate(100,100,50);
rectMode(CENTER);
rect(0,0,8,8); When using translate(), the rectangle’s location
is (0,0) since translate() moved us to the location
for the rectangle.
fi g. 14.4
Finally, we can use a variable for the Z location and animate the shape moving toward us.