I’m doing a pygame project for practice and I need a sprite to move to some point on screen and I did it, but it moves in a straight line and I would like to learn how to make it move to the same point in a curve.
def move_to_point(self, dest_rect, speed, delta_time): # Calculates relative rect of dest rel_x = self.rect.x - dest_rect[0] rel_y = self.rect.y - dest_rect[1] # Calculates diagonal distance and angle from entity rect to destination rect dist = math.sqrt(rel_x**2 + rel_y**2) angle = math.atan2( - rel_y, - rel_x) # Divides distance to value that later gives apropriate delta x and y for the given speed # there needs to be at least +2 at the end for it to work with all speeds delta_dist = dist / (speed * delta_time) + 5 print(speed * delta_time) # If delta_dist is greater than dist entety movement is jittery if delta_dist > dist: delta_dist = dist # Calculates delta x and y delta_x = math.cos(angle) * (delta_dist) delta_y = math.sin(angle) * (delta_dist) if dist > 0: self.rect.x += delta_x self.rect.y += delta_y
This movement looks like
and I would like it to be like
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Answer
There are many many ways to achieve what you want. One possibility is a Bézier curve:
def bezier(p0, p1, p2, t): px = p0[0]*(1-t)**2 + 2*(1-t)*t*p1[0] + p2[0]*t**2 py = p0[1]*(1-t)**2 + 2*(1-t)*t*p1[1] + p2[1]*t**2 return px, py
p0
, p1
and p2
are the control points and t
is a value in the range [0,0, 1,0] indicating the position along the curve. p0
is the start of the curve and p2
is the end of the curve. If t = 0
, the point returned by the bezier function is equal to p0
. If t=1
, the point returned is equal to p2
.
Also see PyGameExamplesAndAnswers – Shape and contour – Bezier
Minimal example:
import pygame pygame.init() window = pygame.display.set_mode((500, 500)) clock = pygame.time.Clock() def bezier(p0, p1, p2, t): px = p0[0]*(1-t)**2 + 2*(1-t)*t*p1[0] + p2[0]*t**2 py = p0[1]*(1-t)**2 + 2*(1-t)*t*p1[1] + p2[1]*t**2 return px, py dx = 0 run = True while run: clock.tick(100) for event in pygame.event.get(): if event.type == pygame.QUIT: run = False pts = [(100, 100), (100, 400), (400, 400)] window.fill(0) for p in pts: pygame.draw.circle(window, (255, 255, 255), p, 5) for i in range(101): x, y = bezier(*pts, i / 100) pygame.draw.rect(window, (255, 255, 0), (x, y, 1, 1)) p = bezier(*pts, dx / 100) dx = (dx + 1) % 101 pygame.draw.circle(window, (255, 0, 0), p, 5) pygame.display.update() pygame.quit() exit()