/**
* Calculates an intersection with the face of a block defined by 3 points.
*
* @param blockPos The position of the block to intersect with
* @param v0 Point 1
* @param v1 Point 2
* @param v2 Point 3
* @param origin Origin of the intersection ray
* @param ray Direction of the intersection ray
* @return Ray-face-intersection
*/
private static RayBoxIntersection rayFaceIntersection(
Vector3f blockPos, Vector3f v0, Vector3f v1, Vector3f v2, Vector3f origin, Vector3f ray) {
// Calculate the plane to intersect with
Vector3f a = Vector3f.sub(v1, v0, null);
Vector3f b = Vector3f.sub(v2, v0, null);
Vector3f norm = Vector3f.cross(a, b, null);
float d = -(norm.x * v0.x + norm.y * v0.y + norm.z * v0.z);
/** Calculate the distance on the ray, where the intersection occurs. */
float t =
-(norm.x * origin.x + norm.y * origin.y + norm.z * origin.z + d)
/ (Vector3f.dot(ray, norm));
if (t < 0) {
return null;
}
/** Calc. the point of intersection. */
Vector3f intersectPoint = VectorPool.getVector(ray.x * t, ray.y * t, ray.z * t);
Vector3f.add(intersectPoint, origin, intersectPoint);
if (intersectPoint.x >= v0.x
&& intersectPoint.x <= v2.x
&& intersectPoint.y >= v0.y
&& intersectPoint.y <= v2.y
&& intersectPoint.z >= v0.z
&& intersectPoint.z <= v2.z) {
return new RayBoxIntersection(blockPos, v0, v1, v2, d, t, origin, ray, intersectPoint);
}
return null;
}
/**
* Returns the vertices of a block at the given position.
*
* @param x
* @param y
* @param z
* @return
*/
private static Vector3f[] verticesForBlockAt(int x, int y, int z) {
Vector3f[] vertices = new Vector3f[8];
vertices[0] = VectorPool.getVector(x - .5f, y - .5f, z - .5f);
vertices[1] = VectorPool.getVector(x + .5f, y - .5f, z - .5f);
vertices[2] = VectorPool.getVector(x + .5f, y + .5f, z - .5f);
vertices[3] = VectorPool.getVector(x - .5f, y + .5f, z - .5f);
vertices[4] = VectorPool.getVector(x - .5f, y - .5f, z + .5f);
vertices[5] = VectorPool.getVector(x + .5f, y - .5f, z + .5f);
vertices[6] = VectorPool.getVector(x + .5f, y + .5f, z + .5f);
vertices[7] = VectorPool.getVector(x - .5f, y + .5f, z + .5f);
return vertices;
}
/**
* Calculates the intersection of a given ray originating from a specified point with a block.
* Returns a list of intersections ordered by the distance to the player.
*
* @param x
* @param y
* @param z
* @param rayOrigin
* @param rayDirection
* @return Distance-ordered list of ray-face-intersections
*/
public static FastList<RayBoxIntersection> rayBlockIntersection(
World w, int x, int y, int z, Vector3f rayOrigin, Vector3f rayDirection) {
/*
* Ignore invisible blocks.
*/
if (Block.getBlockForType(w.getBlock(x, y, z)).isBlockInvisible()) {
return null;
}
FastList<RayBoxIntersection> result = new FastList<RayBoxIntersection>();
/*
* Fetch all vertices of the specified block.
*/
Vector3f[] vertices = verticesForBlockAt(x, y, z);
Vector3f blockPos = VectorPool.getVector(x, y, z);
/*
* Generate a new intersection for each side of the block.
*/
// Front
RayBoxIntersection is =
rayFaceIntersection(
blockPos, vertices[0], vertices[3], vertices[2], rayOrigin, rayDirection);
if (is != null) {
result.add(is);
}
// Back
is =
rayFaceIntersection(
blockPos, vertices[4], vertices[5], vertices[6], rayOrigin, rayDirection);
if (is != null) {
result.add(is);
}
// Left
is =
rayFaceIntersection(
blockPos, vertices[0], vertices[4], vertices[7], rayOrigin, rayDirection);
if (is != null) {
result.add(is);
}
// Right
is =
rayFaceIntersection(
blockPos, vertices[1], vertices[2], vertices[6], rayOrigin, rayDirection);
if (is != null) {
result.add(is);
}
// Top
is =
rayFaceIntersection(
blockPos, vertices[3], vertices[7], vertices[6], rayOrigin, rayDirection);
if (is != null) {
result.add(is);
}
// Bottom
is =
rayFaceIntersection(
blockPos, vertices[0], vertices[1], vertices[5], rayOrigin, rayDirection);
if (is != null) {
result.add(is);
}
/*
* Sort the intersections by distance.
*/
Collections.sort(result);
return result;
}