private boolean moveHorizontal(
      Vector3f horizMove,
      CharacterCollider collider,
      Vector3f position,
      float slopeFactor,
      float stepHeight) {
    float remainingFraction = 1.0f;
    float dist = horizMove.length();
    if (dist < physics.getEpsilon()) {
      return false;
    }
    boolean horizontalHit = false;
    Vector3f normalizedDir = Vector3fUtil.safeNormalize(horizMove, new Vector3f());

    if (collider == null) {
      // ignore collision
      normalizedDir.scale(dist);
      position.add(normalizedDir);
      return false;
    }

    Vector3f targetPos = new Vector3f(normalizedDir);
    targetPos.scale(dist + HORIZONTAL_PENETRATION_LEEWAY);
    targetPos.add(position);
    int iteration = 0;
    Vector3f lastHitNormal = new Vector3f(0, 1, 0);
    while (remainingFraction >= 0.01f && iteration++ < 10) {
      SweepCallback callback =
          collider.sweep(position, targetPos, HORIZONTAL_PENETRATION, slopeFactor);

      /* Note: this isn't quite correct (after the first iteration the closestHitFraction is only for part of the moment)
      but probably close enough */
      float actualDist =
          Math.max(
              0,
              (dist + HORIZONTAL_PENETRATION_LEEWAY) * callback.getClosestHitFraction()
                  - HORIZONTAL_PENETRATION_LEEWAY);
      if (actualDist != 0) {
        remainingFraction -= actualDist / dist;
      }
      if (callback.hasHit()) {
        if (actualDist > physics.getEpsilon()) {
          Vector3f actualMove = new Vector3f(normalizedDir);
          actualMove.scale(actualDist);
          position.add(actualMove);
        }
        dist -= actualDist;
        Vector3f newDir = new Vector3f(normalizedDir);
        newDir.scale(dist);
        float slope = callback.getHitNormalWorld().dot(new Vector3f(0, 1, 0));

        // We step up if we're hitting a big slope, or if we're grazing
        // the ground, otherwise we move up a shallow slope.
        if (slope < slopeFactor || 1 - slope < physics.getEpsilon()) {
          boolean stepping =
              checkStep(collider, position, newDir, callback, slopeFactor, stepHeight);
          if (!stepping) {
            horizontalHit = true;
            Vector3f newHorizDir = new Vector3f(newDir.x, 0, newDir.z);
            Vector3f horizNormal =
                new Vector3f(callback.getHitNormalWorld().x, 0, callback.getHitNormalWorld().z);
            if (horizNormal.lengthSquared() > physics.getEpsilon()) {
              horizNormal.normalize();
              if (lastHitNormal.dot(horizNormal) > physics.getEpsilon()) {
                break;
              }
              lastHitNormal.set(horizNormal);
              extractResidualMovement(horizNormal, newHorizDir);
            }
            newDir.set(newHorizDir);
          }
        } else {
          // Hitting a shallow slope, move up it
          Vector3f newHorizDir = new Vector3f(newDir.x, 0, newDir.z);
          extractResidualMovement(callback.getHitNormalWorld(), newDir);
          Vector3f modHorizDir = new Vector3f(newDir);
          modHorizDir.y = 0;
          newDir.scale(newHorizDir.length() / modHorizDir.length());
        }
        float sqrDist = newDir.lengthSquared();
        if (sqrDist > physics.getEpsilon()) {
          newDir.normalize();
          if (newDir.dot(normalizedDir) <= 0.0f) {
            break;
          }
        } else {
          break;
        }
        dist = (float) Math.sqrt(sqrDist);
        normalizedDir.set(newDir);
        targetPos.set(normalizedDir);
        targetPos.scale(dist + HORIZONTAL_PENETRATION_LEEWAY);
        targetPos.add(position);
      } else {
        normalizedDir.scale(dist);
        position.add(normalizedDir);
        break;
      }
    }
    return horizontalHit;
  }
  private void walk(
      final CharacterMovementComponent movementComp,
      final CharacterStateEvent state,
      CharacterMoveInputEvent input,
      EntityRef entity) {
    Vector3f desiredVelocity = new Vector3f(input.getMovementDirection());

    float lengthSquared = desiredVelocity.lengthSquared();

    // If the length of desired movement is > 1, normalise it to prevent movement being faster than
    // allowed.
    // (Desired velocity < 1 is allowed, as the character may wish to walk/crawl/otherwise move
    // slowly)
    if (lengthSquared > 1) {
      desiredVelocity.normalize();
    }
    desiredVelocity.scale(movementComp.speedMultiplier);

    float maxSpeed = getMaxSpeed(entity, movementComp);
    if (input.isRunning()) {
      maxSpeed *= movementComp.runFactor;
    }

    // As we can't use it, remove the y component of desired movement while maintaining speed.
    if (movementComp.grounded && desiredVelocity.y != 0) {
      float speed = desiredVelocity.length();
      desiredVelocity.y = 0;
      if (desiredVelocity.x != 0 || desiredVelocity.z != 0) {
        desiredVelocity.normalize();
        desiredVelocity.scale(speed);
      }
    }
    desiredVelocity.scale(maxSpeed);

    if (movementComp.mode == MovementMode.CLIMBING) {
      climb(state, input, desiredVelocity);
    }

    // Modify velocity towards desired, up to the maximum rate determined by friction
    Vector3f velocityDiff = new Vector3f(desiredVelocity);
    velocityDiff.sub(state.getVelocity());
    velocityDiff.scale(Math.min(movementComp.mode.scaleInertia * input.getDelta(), 1.0f));
    Vector3f endVelocity = new Vector3f(state.getVelocity());
    endVelocity.x += velocityDiff.x;
    endVelocity.z += velocityDiff.z;
    if (movementComp.mode.scaleGravity == 0) {
      // apply the velocity without gravity
      endVelocity.y += velocityDiff.y;
    } else if (movementComp.mode.applyInertiaToVertical) {
      endVelocity.y +=
          Math.max(
              -TERMINAL_VELOCITY,
              velocityDiff.y - (GRAVITY * movementComp.mode.scaleGravity) * input.getDelta());
    } else {
      endVelocity.y =
          Math.max(
              -TERMINAL_VELOCITY,
              state.getVelocity().y
                  - (GRAVITY * movementComp.mode.scaleGravity) * input.getDelta());
    }
    Vector3f moveDelta = new Vector3f(endVelocity);
    moveDelta.scale(input.getDelta());
    CharacterCollider collider =
        movementComp.mode.useCollision ? physics.getCharacterCollider(entity) : null;
    MoveResult moveResult =
        move(
            state.getPosition(),
            moveDelta,
            (state.getMode() != MovementMode.CLIMBING
                    && state.isGrounded()
                    && movementComp.mode.canBeGrounded)
                ? movementComp.stepHeight
                : 0,
            movementComp.slopeFactor,
            collider);
    Vector3f distanceMoved = new Vector3f(moveResult.getFinalPosition());
    distanceMoved.sub(state.getPosition());
    state.getPosition().set(moveResult.getFinalPosition());
    if (input.isFirstRun() && distanceMoved.length() > 0) {
      entity.send(new MovedEvent(distanceMoved, state.getPosition()));
    }

    if (moveResult.isBottomHit()) {
      if (!state.isGrounded() && movementComp.mode.canBeGrounded) {
        if (input.isFirstRun()) {
          Vector3f landVelocity = new Vector3f(state.getVelocity());
          landVelocity.y +=
              (distanceMoved.y / moveDelta.y) * (endVelocity.y - state.getVelocity().y);
          logger.debug("Landed at " + landVelocity);
          entity.send(new VerticalCollisionEvent(state.getPosition(), landVelocity));
        }
        state.setGrounded(true);
      }
      endVelocity.y = 0;

      // Jumping is only possible, if the entity is standing on ground
      if (input.isJumpRequested()) {
        state.setGrounded(false);
        endVelocity.y += movementComp.jumpSpeed;
        if (input.isFirstRun()) {
          entity.send(new JumpEvent());
        }
      }
    } else {
      if (moveResult.isTopHit() && endVelocity.y > 0) {
        endVelocity.y = -0.5f * endVelocity.y;
      }
      state.setGrounded(false);
    }
    state.getVelocity().set(endVelocity);
    if (input.isFirstRun() && moveResult.isHorizontalHit()) {
      entity.send(new HorizontalCollisionEvent(state.getPosition(), state.getVelocity()));
    }
    if (state.isGrounded()
        || movementComp.mode == MovementMode.SWIMMING
        || movementComp.mode == MovementMode.DIVING) {
      state.setFootstepDelta(
          state.getFootstepDelta()
              + distanceMoved.length() / movementComp.distanceBetweenFootsteps);
      if (state.getFootstepDelta() > 1) {
        state.setFootstepDelta(state.getFootstepDelta() - 1);
        if (input.isFirstRun()) {
          switch (movementComp.mode) {
            case WALKING:
              entity.send(new FootstepEvent());
              break;
            case DIVING:
            case SWIMMING:
              entity.send(new SwimStrokeEvent(worldProvider.getBlock(state.getPosition())));
              break;
          }
        }
      }
    }
  }
  private boolean moveDown(
      float dist, float slopeFactor, CharacterCollider collider, Vector3f position) {
    if (collider == null) {
      position.y += dist;
      return false;
    }

    float remainingDist = -dist;
    Vector3f targetPos = new Vector3f(position);
    targetPos.y -= remainingDist + VERTICAL_PENETRATION_LEEWAY;
    Vector3f normalizedDir = new Vector3f(0, -1, 0);
    boolean hit = false;
    int iteration = 0;
    while (remainingDist > physics.getEpsilon() && iteration++ < 10) {
      SweepCallback callback = collider.sweep(position, targetPos, VERTICAL_PENETRATION, -1.0f);
      float actualDist =
          Math.max(
              0,
              (remainingDist + VERTICAL_PENETRATION_LEEWAY) * callback.getClosestHitFraction()
                  - VERTICAL_PENETRATION_LEEWAY);
      Vector3f expectedMove = new Vector3f(targetPos);
      expectedMove.sub(position);
      if (expectedMove.lengthSquared() > physics.getEpsilon()) {
        expectedMove.normalize();
        expectedMove.scale(actualDist);
        position.add(expectedMove);
      }
      remainingDist -= actualDist;
      if (remainingDist < physics.getEpsilon()) {
        break;
      }
      if (callback.hasHit()) {
        float originalSlope = callback.getHitNormalWorld().dot(new Vector3f(0, 1, 0));
        if (originalSlope < slopeFactor) {
          float slope = callback.calculateAverageSlope(originalSlope, CHECK_FORWARD_DIST);
          if (slope < slopeFactor) {
            remainingDist -= actualDist;
            expectedMove.set(targetPos);
            expectedMove.sub(position);
            extractResidualMovement(callback.getHitNormalWorld(), expectedMove);
            float sqrDist = expectedMove.lengthSquared();
            if (sqrDist > physics.getEpsilon()) {
              expectedMove.normalize();
              if (expectedMove.dot(normalizedDir) <= 0.0f) {
                hit = true;
                break;
              }
            } else {
              hit = true;
              break;
            }
            if (expectedMove.y > -physics.getEpsilon()) {
              hit = true;
              break;
            }
            normalizedDir.set(expectedMove);
            expectedMove.scale(-remainingDist / expectedMove.y + HORIZONTAL_PENETRATION_LEEWAY);
            targetPos.set(position);
            targetPos.add(expectedMove);
          } else {
            hit = true;
            break;
          }
        } else {
          hit = true;
          break;
        }
      } else {
        break;
      }
    }
    if (iteration >= 10) {
      hit = true;
    }
    return hit;
  }