Get x,y by angle and distance

Question

I have problem with results of math operators. I want to draw the line with range =100 by using angle but i get different lenght on screen... I use sin/cos operators and angle of line. Print results are correct values but on screen line is shorter.

My code

        """Class"""
        
        class Knight(pygame.sprite.Sprite):
[..]                
                # Knight spear
                self.spear_color = (0, 0, 0)
                self.spear_length = 100  # pixels
                self.spear_angle = 0
                # Movement
                self.speed = 0
                self.direction = direct  # 1=right, -1=left
        
            def setSpearPosition(self, angle):
                """ The user has adjusted the spear position, regenerate the Knight's image """
                self.spear_angle = angle
        
        
            def raiseSpear(self):
                self.setSpearPosition(self.spear_angle + 1 + random.randint(0, 2))
        
            def lowerSpear(self):
                self.setSpearPosition(self.spear_angle - 1 - random.randint(0, 2))
        
        
    #[oder classes...]
        
        
    #[screen...]
        
    #[Values and sprite groups]
        
        while True:
            for event in pygame.event.get():
                if event.type == pygame.QUIT:
                    pygame.quit()
                    exit()
        
                # handle player input
                keys = pygame.key.get_pressed()
                # Moving knight
                if game_active:
                    if event.type == pygame.KEYDOWN:
                       #Key input
        
                # Draw the screen
        
                # Knight1 spear
                K1_spear_point_x = Knight1.rect.x + (Knight1.spear_length * math.sin(math.radians(Knight1.spear_angle)))
                K1_spear_point_y = Knight1.rect.y + (Knight1.spear_length * math.cos(math.radians(Knight1.spear_angle)))
                pygame.draw.line(screen, Knight1.spear_color,
                                 (Knight1.rect.x + Knight1.rect.width / 2, Knight1.rect.y + Knight1.rect.height / 2),
                                 (K1_spear_point_x, K1_spear_point_y), 2)
        
                # Knight2 spear
                K2_spear_point_x = Knight2.rect.x - (Knight2.spear_length * math.sin(math.radians(Knight2.spear_angle)))
                K2_spear_point_y = Knight2.rect.y - (Knight2.spear_length * math.cos(math.radians(Knight2.spear_angle)))
                pygame.draw.line(screen, Knight2.spear_color,
                                 (Knight2.rect.x + Knight2.rect.width / 2, Knight2.rect.y + Knight2.rect.height / 2),
                                 (K2_spear_point_x, K2_spear_point_y), 2)
    #[code...]

Edit: I changed starting point of my lines... All works perfect

K1_spear_point_x = (Knight1.rect.x+Knight1.rect.width / 2) + (Knight1.spear_length * math.cos(math.radians(Knight1.spear_angle)))
K1_spear_point_y = (Knight1.rect.y+ Knight1.rect.height / 2) + (Knight1.spear_length * math.sin(math.radians(Knight1.spear_angle)))
pygame.draw.line(screen, Knight1.spear_color,
                 (Knight1.rect.x + Knight1.rect.width / 2, Knight1.rect.y + Knight1.rect.height / 2),
                 (K1_spear_point_x, K1_spear_point_y), 2)

# Knight2 spear
K2_spear_point_x = (Knight2.rect.x+Knight2.rect.width / 2) - (Knight2.spear_length * math.cos(math.radians(Knight2.spear_angle)))
K2_spear_point_y = (Knight2.rect.y+ Knight2.rect.height / 2) + (Knight2.spear_length * math.sin(math.radians(Knight2.spear_angle)))
pygame.draw.line(screen, Knight2.spear_color,
                 (Knight2.rect.x + Knight2.rect.width / 2, Knight2.rect.y + Knight2.rect.height / 2),
                 (K2_spear_point_x, K2_spear_point_y), 2)

Get x,y by angle and distance

0 Answers