Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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translate(width/2, height/2);
beginShape();
texture(PimageObjectNameGoesHere)
vertex(-100, -100, 0, 0);
vertex(100, -100, 200, 0);
vertex(100, 100, 200, 200);
vertex(-100, 100, 0, 200);
endShape(CLOSE);
To map the image larger on the same geometry, you’d decrease the uv coordinates values
(only values greater than 0 will have any effect). Increasing uv values beyond the actual
size of the image will have no effect.
Returning to the Asteroid Shower sketch, it wasn’t easy to map the Earth image onto the
irregular ground shape. I created the two variables, as follows:
float imageShiftX = 20;
float imageShiftY = -240;
to help ensure that the image would map properly. I recommend messing with these values
to see what happens.
Next in the draw() function is the drawing and moving of the orbs, which is pretty
straightforward. What might be less obvious, though, is how to handle the collisions
between the multiple ground segments and the multiple orbs. The crux of this problem is
remembering to check the collision between each orb against every ground segment.
When you come up against a programming problem with two sets of objects that need to
interact like this, the solution is often a nested loop—which is precisely what I used to
solve the collision problem. Thus, each orb gets born within the outer for loop and then
gets passed to the checkGroundCollision() function, which is called within another
nested for loop that executes the number of times there are ground segments. Each time
the inner loop is called, the current orb, velocity, and damping values (controlled by
the outer loop), and the ground segment (specified by the inner loop) are passed to the
checkGroundCollision() function. Again, this inner loop will run the number of times
there are segments and then control will return to the outer loop to begin the process
over again.
The last conditional in the draw() function
if (emitter < orbCount-1){
emitter += birthRate;
}
simply ensures that the emitter used to control the birthrate of orbs doesn’t exceed the
total orb count specified earlier in the sketch. We’re almost done.
To keep your workload down some, I edited the checkGroundCollision() and
checkWallCollision() functions in such a way that all you need to do is add some parameters
to the two functions. Thus, between stage 2 and stage 3, you just need to replace
void checkGroundCollision(Ground groundSegment) {