/** Constructor: Sets up this panel and loads the images. */
public Engine() {
addKeyListener(new Controller());
setBackground(Color.black);
setPreferredSize(new Dimension(WIDTH, HEIGHT));
setFocusable(true);
// init world
final int defWidth = 150;
final int defHeight = 15;
final Random gen = new Random();
// 50% random, 25% hills, 25% platform
if (gen.nextBoolean()) {
world = RandomLevel.genWorldRandom(defWidth, defHeight, tp);
} else {
if (gen.nextBoolean()) {
world = RandomLevel.genWorldHills(defWidth, defHeight, tp);
} else {
world = RandomLevel.genWorldPlatform(defWidth, defHeight, tp);
}
}
// world = new Level("house.txt", tp);
// init hero
hero = new Hero();
hero.setImage(tp.get(Texture.hero));
hero.setPos(world.getStart());
renderer.addDynProp(hero);
renderer.setWorld(world);
// init test light
Point[] bgLights = world.getAll(Texture.bgLightDead);
Light tempLight;
final int cso = 15; // Cell size offset.
final int rRange = 100;
final int rMin = 75;
for (Point light : bgLights) {
tempLight = new Light(light.x + cso, light.y + cso, world);
tempLight.setRadius((short) (Math.random() * rRange + rMin));
renderer.addStaticProp(tempLight);
triggers.add(tempLight);
}
// Don't start this loop until setup is complete!
if (thread == null) {
running = true;
thread = new Thread(this);
thread.start();
}
}
/**
* Compare an object to the world to identify any collisions. The obj is compared to blocks it is
* directly overtop of. Returns null if no collisions are found.
*
* @param obj The entity to test against the world.
* @param target The block type to test for
* @return the first collision found, if any. Null if none.
*/
private Point getWorldCollision(Dynamic obj, Texture target) {
Rectangle r = obj.getCollisionBox();
Point lowerLeft = new Point(r.x, r.y);
Point upperRight = new Point(r.x + r.width - 1, r.y + r.height - 1);
int cell = World.CELL_SIZE;
// If x is negative, offset by 1. It sucks but is necessary.
if (lowerLeft.x < 0) {
lowerLeft.x -= cell;
}
if (upperRight.x < 0) {
upperRight.x -= cell;
}
// Convert pixel coordinates to world coordinates.
lowerLeft.x /= cell;
lowerLeft.y /= cell;
upperRight.x /= cell;
upperRight.y /= cell;
// Test for overlap with the target block type
for (int x = (lowerLeft.x); x <= (upperRight.x); x++) {
for (int y = (lowerLeft.y); y <= (upperRight.y); y++) {
if (world.getCell(x, y) == target) {
return new Point(x, y);
}
}
}
return null;
}
/**
* 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);
}
}
