/**
* Calculate the physics in our world for the given object.
*
* @param obj The object to move
* @param timeStep The time since last evaluation in nanoseconds
*/
public void simulate(Dynamic obj, long timeStep) {
/* Actions:
* 1. apply drag
* 2. add forces to object
* - gravity (unless resting on block)
* - arrow keys
*
* 3. apply forces to object. (done by the object)
*
* 4. a) move in x axis
* 5. a) resolve collisions in x axis
*
* 4. b) move in y axis
* 5. b) resolve collisions in y axis
*/
double seconds = timeStep / (double) NS_PER_S;
// 1. apply drag
obj.applyDrag(seconds);
// 2. add forces
obj.addForce(new Vector2D(0, GRAVITY));
obj.addForce(keyForce);
// 3. apply forces
obj.applyForces(seconds);
// get velocity in preparation for step 4
Vector2D vel = obj.getVel();
hero.setImage(tp.get(Texture.hero));
// 4. a) move x
obj.move((int) (vel.x * seconds), 0);
// 5. a) resolve collisions in x
Point bad = getWorldCollision(obj, Texture.brick);
// bad = null;
if (bad != null) {
int resolution = world.escapeX(obj, vel.x * seconds, bad);
obj.move(resolution, 0);
obj.getVel().setX(0);
}
// 4. b) move y
obj.move(0, (int) (vel.y * seconds));
// 5. b) resolve collisions in y
bad = getWorldCollision(obj, Texture.brick);
// bad = null;
if (bad != null) {
int resolution = world.escapeY(obj, vel.y * seconds, bad);
if (vel.y < 0) {
hero.setOnGround(true);
hero.setImage(tp.get(Texture.heroGround));
}
obj.move(0, resolution);
obj.getVel().setY(0);
} else {
hero.setOnGround(false);
}
}
