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Contents
#
# Bouncing Ball with Vectors
# by Daniel Shiffman.
# PVector was used in the original (instead of Vec2D)
#
# Demonstration of using vectors to control motion of body
# This example is not object-oriented
# See AccelerationWithVectors for an example of how to simulate motion using vectors in an object
#
load_library :vecmath
RADIUS = 24
attr_reader :loc, # Location of shape
:velocity, # Velocity of shape
:gravity # Gravity acts at the shape's acceleration
def setup
size(640, 360)
smooth 4
@loc = Vec2D.new(100, 100)
@velocity = Vec2D.new(1.5, 2.1)
@gravity = Vec2D.new(0, 0.2)
end
def draw
background(0)
# Add velocity to the location.
@loc += velocity
# Add gravity to velocity
@velocity += gravity
# Bounce off edges
velocity.x *= -1 unless (RADIUS .. width - RADIUS).include?(loc.x)
if loc.y > (height - RADIUS)
# We're reducing velocity ever so slightly
# when it hits the bottom of the window
velocity.y *= -0.95
loc.y = height - RADIUS
end
# Display circle at location vector
stroke(255)
stroke_weight(2)
fill(127)
ellipse(loc.x, loc.y, RADIUS * 2, RADIUS * 2)
end
Version data entries
5 entries across 5 versions & 1 rubygems