CODEWITHSUNDEEP
pythonpygamecollisionpymunk
Meric Ozcan
Meric Ozcan

Reputation: 818

Python Pygame and Pymunk game library Non-colliding Shapes

In my game I would like to create non-colliding balls. This is the code which creates blue and red balls with right and left click with mouse.. However as you can see balls collide even though I categorized them and mask them as I commented. 

import sys
import pygame as pg
from pygame.color import THECOLORS
import pymunk as pm


def to_pygame(p):
    """Small hack to convert pymunk to pygame coordinates"""
    return int(p[0]), int(-p[1]+600)


pg.init()
screen = pg.display.set_mode((600, 600))
clock = pg.time.Clock()

space = pm.Space()
space.gravity = (0.0, -900.0)

# Walls
static_body = space.static_body
static_lines = [
    pm.Segment(static_body, (111.0, 280.0), (407.0, 246.0), 0.0),
    pm.Segment(static_body, (407.0, 246.0), (407.0, 343.0), 0.0),
    pm.Segment(static_body, (111.0, 420.0), (407.0, 386.0), 0.0),
    pm.Segment(static_body, (407.0, 386.0), (407.0, 493.0), 0.0),
    ]
for idx, line in enumerate(static_lines):
    line.elasticity = 0.95
    if idx < 2:  # Lower lines.
        # The lower lines are in category 2, in binary 0b10.
        line.filter = pm.ShapeFilter(categories=2)
    else:  # Upper lines.
        # The upper lines are in category 1, in binary 0b1.
        line.filter = pm.ShapeFilter(categories=1)
space.add(static_lines)

balls = []
running = True

while running:
    for event in pg.event.get():
        if event.type == pg.QUIT:
            running = False
        elif event.type == pg.KEYDOWN and event.key == pg.K_ESCAPE:
            running = False
        if event.type == pg.MOUSEBUTTONDOWN:
            radius = 15 if event.button == 1 else 30
            mass = 10
            inertia = pm.moment_for_circle(mass, 0, radius, (0,0))
            body = pm.Body(mass, inertia)
            body.position = to_pygame(event.pos)
            shape = pm.Circle(body, radius, (0,0))
            shape.elasticity = 0.95
            if shape.radius > 25:
                # bin(pm.ShapeFilter.ALL_MASKS ^ 1) is '0b11111111111111111111111111111110'
                # That means all categories are checked for collisions except
                # bit 1 (the upper lines) which are ignored.
                #### HOW EVER BALSS COLLIDE
                shape.filter = pm.ShapeFilter(categories=0x1)
                shape.filter = pm.ShapeFilter(mask=pm.ShapeFilter.ALL_MASKS ^ 1)
            else:
                # Ignores category bin(2), '0b11111111111111111111111111111101'
                # All categories are checked for collisions except bit 2 (the lower lines).
                #### HOW EVER BALSS COLLIDE
                shape.filter = pm.ShapeFilter(categories=0x2)
                shape.filter = pm.ShapeFilter(mask=pm.ShapeFilter.ALL_MASKS ^ 2)

            space.add(body, shape)
            balls.append(shape)

    screen.fill(THECOLORS["white"])

    balls_to_remove = []
    for ball in balls:
        if ball.body.position.y < 100:
            balls_to_remove.append(ball)

        p = to_pygame(ball.body.position)
        if ball.radius > 25:
            color = THECOLORS["red"]
        else:
            color = THECOLORS["blue"]
        pg.draw.circle(screen, color, p, int(ball.radius), 2)

    for ball in balls_to_remove:
        space.remove(ball, ball.body)
        balls.remove(ball)

    for line in static_lines:
        body = line.body
        pv1 = body.position + line.a.rotated(body.angle)
        pv2 = body.position + line.b.rotated(body.angle)
        p1 = to_pygame(pv1)
        p2 = to_pygame(pv2)
        pg.draw.lines(screen, THECOLORS["gray29"], False, [p1, p2])

    # Update physics.
    dt = 1.0/60.0
    for x in range(1):
        space.step(dt)

    pg.display.flip()
    clock.tick(50)


pg.quit()
sys.exit()

Balls DONT Collide with walls but themselves. I want non-colliding balls only!

P.S: Example Library shape filter class:

http://www.pymunk.org/en/latest/pymunk.html#pymunk.ShapeFilter

Upvotes: 2

Views: 417

Answers (1)

skrx
skrx

Reputation: 20438

You need to put the balls into their own category and then adjust the masks, so that they don't collide with this category. For example to turn off the collision for the big red balls, you can put them into category 0b100:

shape.filter = pm.ShapeFilter(categories=0b100, mask=pm.ShapeFilter.ALL_MASKS ^ 0b100)

The mask=pm.ShapeFilter.ALL_MASKS ^ 0b100 argument means objects in this category should be ignored.

Upvotes: 2

Related Questions