Finetuning movement based on gradual rotation towards a target
- by A.B.
I have an object which moves towards a target destination by gradually adjusting its facing while moving forwards. If the target destination is in a "blind spot", then the object is incapable of reaching it.
This problem is ilustrated in the picture below. When the arrow is ordered to move to point A, it will only end up circling around it (following the red circle) because it is not able to adjust its rotation quickly enough.
I'm interested in a solution where the movement speed is multiplied by a number from 0.1 to 1 in proportion to necessity. The problem is, how do I calculate whether it is necessary in the first place? How do I calculate an appropriate multiplier that is neither too small nor too large?
void moveToPoint(sf::Vector2f destination) {
if (destination == position) return;
auto movement_distance = distanceBetweenPoints(position, destination);
desired_rotation = angleBetweenPoints(position, destination);
/// Check whether rotation should be adjusted
if (rotation != desired_rotation) {
/// Check whether the object can achieve the desired rotation within the next adjustment of its rotation
if (Radian::isWithinDistance(rotation, desired_rotation, rotation_speed)) {
rotation = desired_rotation;
} else {
/// Determine whether to increment or decrement rotation in order to achieve desired rotation
if (Radian::convert(desired_rotation - rotation) > 0) {
/// Increment rotation
rotation += rotation_speed;
} else {
/// Decrement rotation
rotation -= rotation_speed;
}
}
}
if (movement_distance < movement_speed) {
position = destination;
} else {
position.x = position.x + movement_speed*cos(rotation);
position.y = position.y + movement_speed*sin(rotation);
}
updateGraphics();
}
