【发布时间】：2013-06-24 17:54:11
【问题描述】：
我正在尝试为 我正在开发的基于体素的 3D Java 游戏。我正在尝试实施 该网站的算法： https://sites.google.com/site/letsmakeavoxelengine/home/collision-detection, 但我似乎无法做到这一点。我的问题 是，他所说的“将玩家位置转换为 体素空间”。我应该将玩家的坐标四舍五入到 最近的块，这样玩家所在的体素就是那个 玩家的中心在哪里？在我的游戏中，玩家 目前是一个体素大小的立方体。
那个网站上的人写道，他只需要检查一个 碰撞体素。但如果我只检查体素中心 的球员在，那么球员的中心需要 在他与他们碰撞之前相交东西。这不应该 是这样的吗？如果玩家的中心在 非活动体素，但玩家立方体的一部分正在相交 一个活跃的体素，那么我应该检查哪个体素？
我知道这段文字很混乱，但我希望你能 理解我的问题。如果您想查看一些代码，这是我的 CollisionHandler 类：（由于我遇到的问题，它并没有真正遵循上面网站的算法。它只关心沿 x 轴的碰撞截至目前）
public class CollisionHandler {
private static final float COLLISION_TOLERANCE = 0.4f;
private boolean xCol, yCol, zCol = false;
public void handleCollisions(ChunkManager chunkManager,
FPCameraController player, float delta) {
Vector3D playerPos = player.getPosition();
Vector3D collision = findCollisionVector(player, chunkManager);
if (collidesWithWorld()) {
if (!(player.isFalling() && isGrounded(playerPos, chunkManager))) {
player.setCollisionVector(collision);
player.translateX(-playerPos.subtract(playerPos.round()).getX());
}else{
//123456
}
} else {
if (player.isFalling()) {
if (isGrounded(playerPos, chunkManager)) {
float overlap = getYOverlap(player, chunkManager);
player.translateY(overlap);
player.setYSpeed(0);
player.setIsFalling(false);
} else {
player.applyGravity(delta);
}
} else {
if (!isGrounded(playerPos, chunkManager)) {
player.setIsFalling(true);
player.applyGravity(delta);
}
}
}
}
private boolean collidesWithWorld() {
return xCol || yCol || zCol;
}
/*
* Returns a collision vector. Dot with velocity and then subtract it from
* the player velocity.
*/
private Vector3D findCollisionVector(FPCameraController player,
ChunkManager chunkManager) {
Vector3D playerPos = player.getPosition();
Vector3D distance = playerPos.subtract(playerPos.floor()).abs();
Vector3D collisions = new Vector3D(1, 1, 1);
float xDirection = (getCollisionDirection(distance.getX()));
// float yDirection = (getCollisionDirection(distance.getY()));
// float zDirection = (getCollisionDirection(distance.getZ()));
try {
Vector3D collision = getCollisionNormal(chunkManager, playerPos,
xDirection, 'x');
if (collision != null) {
collisions = collision;
xCol = true;
} else {
xCol = false;
}
// collision = getCollisionNormal(chunkManager, playerPos,
// yDirection,
// 'y');
// if (collision != null) {
// collisions.cross(collision);
// yCol = true;
// } else {
// yCol = false;
// }
//
// collision = getCollisionNormal(chunkManager, playerPos,
// zDirection,
// 'z');
// if (collision != null) {
// collisions.cross(collision);
// zCol = true;
// } else {
// zCol = false;
// }
} catch (OutsideOfWorldException e) {
e.printStackTrace();
}
return collisions;
}
/*
* Returns the normal of the colliding block, given the axis and
* direction.
*/
private static Vector3D getCollisionNormal(ChunkManager chunkManager,
Vector3D playerPos, float direction, char axis)
throws OutsideOfWorldException {
Block b;
Vector3D blockPos;
if (direction != 0) {
Vector3D dirVector;
if (axis == 'x') {
dirVector = new Vector3D(direction, 0, 0);
} else if (axis == 'y') {
dirVector = new Vector3D(0, direction, 0);
} else if (axis == 'z') {
dirVector = new Vector3D(0, 0, direction);
} else {
return null;
}
blockPos = playerPos.add(dirVector);
b = chunkManager.getBlock(blockPos);
if (b.isActive()) {
return Plane3D.getBlockNormal(blockPos, direction, axis);
}
}
return null;
}
private static float getCollisionDirection(float distance) {
if (distance > COLLISION_TOLERANCE) {
return 1;
} else if (distance < COLLISION_TOLERANCE) {
return -1;
}
return 0;
}
private static boolean isGrounded(Vector3D playerPosition,
ChunkManager chunkManager) {
try {
return chunkManager.getBlock(
playerPosition.add(new Vector3D(0, -1, 0))).isActive();
} catch (OutsideOfWorldException e) {
e.printStackTrace();
}
return true;
}
private static float getYOverlap(FPCameraController player,
ChunkManager chunkManager) {
Vector3D playerPosition = player.getPosition();
Vector3D blockPosition = player.getLowestBlockPos();
Block collisionBlock = null;
try {
collisionBlock = chunkManager.getBlock(blockPosition);
// +" "+blockPosition);
if (collisionBlock.isActive()) {
float distance = playerPosition.subtract(blockPosition).getY();
distance += player.getHeight();
return -distance;
}
} catch (OutsideOfWorldException e) {
e.printStackTrace();
}
return 0;
}
}
这是另一个相关的方法：
public static Vector3D getBlockNormal(Vector3D blockPos, float direction,
char axis) {
float offset = Block.BLOCK_RENDER_SIZE / 2f;
Vector3D pointA = null;
Vector3D pointB = null;
Vector3D pointC = null;
Vector3D a = blockPos.round();
a = a.addScalar(Block.BLOCK_RENDER_SIZE / 2f);
float factor = -direction;
if (axis == 'x') {
pointA = a.add(new Vector3D(factor * offset, -offset, -offset));
pointB = a.add(new Vector3D(factor * offset, offset, -offset));
pointC = a.add(new Vector3D(factor * offset, -offset, offset));
} else if (axis == 'y') {
pointA = a.add(new Vector3D(-offset, factor * offset, offset));
pointB = a.add(new Vector3D(offset, factor * offset, offset));
pointC = a.add(new Vector3D(offset, factor * offset, -offset));
} else if (axis == 'z') {
pointA = a.add(new Vector3D(-offset, -offset, factor * offset));
pointB = a.add(new Vector3D(offset, -offset, factor * offset));
pointC = a.add(new Vector3D(offset, offset, factor * offset));
} else {
return null;
}
Vector3D v = new Vector3D(pointB.getX() - pointA.getX(), pointB.getY()
- pointA.getY(), pointB.getZ() - pointA.getZ()).normalize();
Vector3D w = new Vector3D(pointC.getX() - pointA.getX(), pointC.getY()
- pointA.getY(), pointC.getZ() - pointA.getZ()).normalize();
Vector3D normal = v.cross(w).scale(-1);
return normal.scale(factor);
}
【问题讨论】：
标签： java collision-detection game-engine game-physics voxel