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102 lines
2.7 KiB
Python
102 lines
2.7 KiB
Python
import random
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import math
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# the size of the screen
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WIDTH = 800
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HEIGHT = 600
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# how much a particle slows down by each second
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DRAG = 0.8
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# the colour of each particle in R, G, B values
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PARTICLE_COLOR = 255, 230, 128
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# the time in seconds for which a particle is displayed
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MAX_AGE = 3
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# an array to hold the details of the explosion particles on the screen
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particles = []
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# This function creates a new explosion at the specified screen co-ordinates
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def explode(x, y, speed=300):
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# these are new particles, so set their age to zero
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age = 0
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# generate 100 particles per explosion
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for _ in range(100):
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# for each particle, generate a random angle and distance
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angle = random.uniform (0, 2 * math.pi)
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radius = random.uniform(0, 1) ** 0.5
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# convert angle and distance from the explosion point into x and y velocity for the particle
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vx = speed * radius * math.sin(angle)
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vy = speed * radius * math.cos(angle)
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# add the particle's position, velocity and age to the array
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particles.append((x, y, vx, vy, age))
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# This function redraws the screen by plotting each particle in the array
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def draw():
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# clear the screen
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screen.clear()
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# loop through all the particles in the array
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for x, y, *_ in particles:
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# for each particle in the array, plot its position on the screen
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screen.surface.set_at((int(x), int(y)), PARTICLE_COLOR)
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# This function updates the array of particles
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def update(dt):
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# to update the particle array, create a new empty array
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new_particles = []
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# loop through the existing particle array
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for (x, y, vx, vy, age) in particles:
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# if a particle was created more than a certain time ago, it can be removed
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if age + dt > MAX_AGE:
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continue
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# update the particle's velocity - they slow down over time
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drag = DRAG ** dt
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vx *= drag
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vy *= drag
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# update the particle's position according to its velocity
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x += vx * dt
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y += vy * dt
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# update the particle's age
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age += dt
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# add the particle's new position, velocity and age to the new array
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new_particles.append((x, y, vx, vy, age))
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# replace the current array with the new one
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particles[:] = new_particles
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# This function creates an explosion at a random location on the screen
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def explode_random():
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# select a random position on the screen
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x = random.randrange(WIDTH)
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y = random.randrange(HEIGHT)
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# call the explosion function for that position
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explode(x, y)
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# call the random explosion function every 1.5 seconds
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clock.schedule_interval(explode_random, 1.5)
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