Phineas & Ferb Ride Again research

PhysicsTests.java

public class PhysicsTests {
    public static final int Y_ACCELERATION = -16;
    public static final int GROUNDED_Y_VELOCITY = -328;
    public static final int JUMPING_Y_VELOCITY = 328;
    
    public static final int GROUND_UPPER_HITBOX = 40951;
    public static final int GROUND_LOWER_HITBOX = 1654;
    
    /**
     * Calculates the number of frames it will take from right before Phineas is in freefall to
     * the frame Phineas lands on solid ground.
     * 
     * @param startingGround Y position of the starting ground.
     * @param endingGround Y position of the ending ground.
     * @param jumping Whether Phineas jumps prior to falling off the starting ground. If false
     * he will simply walk off the platform.
     * @return The number of frames that pass between Phineas falling off the starting ground
     * and landing on the ending ground.
     */
    public static int verticalOverflowTime(int startingGround, int endingGround, boolean jumping) {
        final int MIN_FRAMES = 10 * 60; // to ensure we are actually using vertical underflow
        
        int frameCounter = 0;
        int yVelocity = jumping ? JUMPING_Y_VELOCITY : GROUNDED_Y_VELOCITY; // might rarely underflow
        int yPosition = startingGround; // will definitely underflow
        
        while (true) {
            yVelocity += Y_ACCELERATION;
            yPosition += yVelocity;
            if (frameCounter == 0 && !jumping) yVelocity = 0;
            
            // upper ground hit detection (happens on frame prior to update)
            if (frameCounter >= MIN_FRAMES && yVelocity < 0 
                    && yPosition > endingGround && yPosition - endingGround <= GROUND_UPPER_HITBOX) 
                break;
            
            frameCounter++;
            
            // lower ground hit detection (happens on frame after update)
            if (frameCounter >= MIN_FRAMES && endingGround > yPosition 
                    && endingGround - yPosition <= GROUND_LOWER_HITBOX) 
                break;
        }
        
        return frameCounter;
    }
}