12.The Cannon Scene

Everything you learned in Part III — forces, integration, collisions — the full simulator runs that same math, just at scale. A "scene" is a list of objects, each with mass, position, friction, and restitution. Press play and the engine does Euler integration on every body, resolving collisions between them.

Your goal: build the classic textbook example. A cannon (a box), a ball (a sphere), and a brick wall (a grid of boxes). Fire the ball into the wall and watch physics take over.

Open the full studio below. Add a ground plane, one box (the cannon body), one sphere (the cannonball), and a stack of boxes (the wall). Position the wall a few units away from the cannon. Don't press play yet.

Use the "Add Objects" panel on the left to place cubes and spheres. Position them using the property inspector.

If the wall is 5 units away and 2 units tall, and the ball starts at height 1 — what horizontal velocity makes it travel 5 units before hitting the ground? Recall: horizontal distance = velocity * time, and time to fall is determined by gravity.

Select the cannonball in the studio. In the property inspector, set its initial velocity (or write a script to set it — you'll do that in the next lesson). Press play and see if it hits the wall.

Challenge: Adjust the ball's initial velocity (angle and magnitude) until it strikes the center of the wall. The bricks should scatter on impact. Save the scene to your library when satisfied.