私は楽しみのために 2D 物理エンジンを書いています。
BoxObject長方形、BallObject円、線など、さまざまな形状に対してさまざまなクラスを作成しましLineObjectた。これらはすべてPhysicsObjectインターフェースを実装します。
シミュレートされているすべてのオブジェクトがリストに存在します。
public static List<PhysicsObject> objects = new ArrayList<PhysicsObject>();
これらのオブジェクトはすべて、相互の衝突をチェックする必要があります。
Collisionクラスには、考えられるすべてのタイプのペア (例: など) の貫通データを取得するために名前が付けられたメソッドが含まれてpenetrationDataいます。penetrationData(BoxObject a, BallObject b)penetrationData(BallObject a, LineObject b)
package com.optimus.game.physics;
public class Collision {
// Default - no collision
public static float[] penetrationData(PhysicsObject a, PhysicsObject b) {
return null;
}
// Line vs Circle
public static float[] penetrationData(LineObject line, BallObject ball) {
float distance = line.distance(ball.x, ball.y);
if (Math.abs(distance) > ball.radius) {
return null;
}
float penetration = ball.radius - Math.abs(distance);
float normalX = line.perpendicularX();
float normalY = line.perpendicularY();
return new float[] {normalX, normalY, penetration};
}
// Circle vs Line
public static float[] penetrationData(BallObject ball, LineObject line) {
float[] data = penetrationData(line, ball);
// reverse the normal
if (data != null) {
data[0] = -data[0];
data[1] = -data[1];
}
return data;
}
// Circle vs Circle
public static float[] penetrationData(BallObject a, BallObject b) {
// Vector from A to B
float normalX = b.x - a.x;
float normalY = b.y - a.y;
float penetration = 0;
// calculate the penetration and normal direction
// ...
// ... (code skipped)
return new float[] {normalX, normalY, penetration};
}
// Rect vs Rect
public static float[] penetrationData(BoxObject a, BoxObject b) {
// Vector from A to B
float normalX = b.x - a.x;
float normalY = b.y - a.y;
float penetration = 0;
// calculate the penetration and normal direction
// ...
// ... (code skipped)
return new float[] {normalX, normalY, penetration};
}
// Rect vs Circle
public static float[] penetrationData(BoxObject box, BallObject ball) {
// Vector from A to B
float normalX = ball.x - (box.x + box.width / 2f);
float normalY = ball.y - (box.y + box.height / 2f);
float penetration = 0;
// calculate the penetration and normal direction
// ...
// ... (code skipped)
return new float[] {normalX, normalY, penetration};
}
// Circle vs Rect
public static float[] penetrationData(BallObject ball, BoxObject box) {
float[] data = penetrationData(box, ball);
// reverse the normal
if (data != null) {
data[0] = -data[0];
data[1] = -data[1];
}
return data;
}
}
そして、私は衝突をチェックします...
public static void checkAndResolveCollisions(List<PhysicsObject> objects) {
// check collision between all objects in a list
// list of objects can contain BallObject, LineObject and
// BoxObject all of which implement PhysicsObject
// loop over all possible pairs
for (int i = 0; i < objects.size(); i++) {
for (int j = i + 1; j < objects.size(); j++) {
// here I want that apt function is called based on type
// but objects.get(int i) always returns a PhysicsObject
float[] data = Collision.penetrationData(objects.get(i), objects.get(j));
// data = null implies no overlap
if (data == null) {
continue;
}
// Calculate relative velocity in terms of the normal direction
float normalX = data[0];
float normalY = data[1];
float penetration = data[2];
// Resolve the collision along the normal
// ...
// ... (code skipped)
}
}
}
しかし、それは機能せず、毎回penetrationData戻ってきます...null
このような侵入データを取得するとうまくいきますが、このコードは悪臭を放ち、見ただけでわかります...
// here is what works, but I know is bad java code
float[] data = getAptPenetrationData(objects.get(i), objects.get(j));
getAptPenetrationData型キャストして apt 関数を呼び出す汎用関数はどこにありますか
// generic function that calls others
public static float[] getAptPenetrationData(PhysicsObject a, PhysicsObject b) {
// bad java code...
boolean aIsBall = a instanceof BallObject;
boolean aIsBox = a instanceof BoxObject;
boolean aIsLine = a instanceof LineObject;
boolean bIsBall = b instanceof BallObject;
boolean bIsBox = b instanceof BoxObject;
boolean bIsLine = b instanceof LineObject;
float[] data = null;
// circle vs circle
if (aIsBall && bIsBall) {
data = Collision.penetrationData((BallObject)a, (BallObject)b);
// box vs box
} else if (aIsBox && bIsBox) {
data = Collision.penetrationData((BoxObject)a, (BoxObject)b);
// box vs circle
} else if (aIsBox && bIsBall) {
data = Collision.penetrationData((BoxObject)a, (BallObject)b);
// circle vs box
} else if (aIsBall && bIsBox) {
data = Collision.penetrationData((BallObject)a, (BoxObject)b);
// circle vs line
} else if (aIsBall && bIsLine) {
data = Collision.penetrationData((BallObject)a, (LineObject)b);
// line vs circle
} else if (aIsLine && bIsBall) {
data = Collision.penetrationData((LineObject)a, (BallObject)b);
}
return data;
}
私は何かが欠けているに違いなく、私がやろうとしていることを行うためのより良い方法があるに違いありません. どんな助けでも大歓迎です。ありがとう。
編集：
Zim-Zam の提案によると、衝突は現在このように解決されています...
public static void checkAndResolveCollisions(List<PhysicsObject> objects) {
// check collision between all objects in a list
// list of objects can contain BallObject, LineObject and
// BoxObject all of which implement PhysicsObject
// loop over all possible pairs
for (int i = 0; i < objects.size(); i++) {
for (int j = i + 1; j < objects.size(); j++) {
// does not work, goes into infinite recursion
// still calls PhysicsObject.penetrationData(PhysicsObject)
float[] data = objects.get(i).penetrationData(objects.get(j));
// data = null implies no overlap
if (data == null) {
continue;
}
// Calculate relative velocity in terms of the normal direction
float normalX = data[0];
float normalY = data[1];
float penetration = data[2];
// Resolve the collision along the normal
// ...
// ... (code skipped)
}
}
}
PhysicsObjectただし、以下のメソッドシグネチャをインターフェイスに追加した場合にのみ機能します
public PenetrationData penetrationData(PhysicsObject other);
public PenetrationData penetrationData(BallObject other);
public PenetrationData penetrationData(BoxObject other);
public PenetrationData penetrationData(LineObject other);
これは、新しいものを実装するたびにPhysicsObjectインターフェイスを変更する必要があるため、まだ理想的ではありません。
PhysicsObject の実装 (penetrationData関数のみ) -
BallObject.java
public class BallObject implements PhysicsObject {
@Override
public float[] penetrationData(PhysicsObject other) {
return other.penetrationData(this);
}
@Override
public float[] penetrationData(LineObject line) {
return Collision.penetrationData(this, line);
}
@Override
public float[] penetrationData(BoxObject box) {
return Collision.penetrationData(this, box);
}
@Override
public float[] penetrationData(BallObject ball) {
return Collision.penetrationData(this, ball);
}
// ... rest of the code
}
BoxObject.java
public class BoxObject implements PhysicsObject {
@Override
public float[] penetrationData(PhysicsObject other) {
return other.penetrationData(this);
}
@Override
public float[] penetrationData(LineObject line) {
return null; // not implemented
}
@Override
public float[] penetrationData(BoxObject box) {
return Collision.penetrationData(this, box);
}
@Override
public float[] penetrationData(BallObject ball) {
return Collision.penetrationData(this, ball);
}
// ... rest of the code
}
LineObject.java
public class LineObject implements PhysicsObject {
@Override
public float[] penetrationData(PhysicsObject other) {
return other.penetrationData(this);
}
@Override
public float[] penetrationData(LineObject line) {
return null; // not implemented
}
@Override
public float[] penetrationData(BoxObject box) {
return null; // not implemented
}
@Override
public float[] penetrationData(BallObject ball) {
return Collision.penetrationData(this, ball);
}
// ... rest of the code
}