From: Skullheadx <704277@pdsb.net>
Date: Mon, 16 Jan 2023 23:18:09 +0000 (-0500)
Subject: Discrete Collision Detection
X-Git-Url: http://git.skullheadx.com/blog/index.html?a=commitdiff_plain;h=1e6fe2a7d5dbcdd5d55e1add03f8761a43691bd2;p=Collision-Simulation.git

Discrete Collision Detection
---

diff --git a/box.py b/box.py
new file mode 100644
index 0000000..cd0bf5b
--- /dev/null
+++ b/box.py
@@ -0,0 +1,22 @@
+from colours import *
+import pygame
+
+
+class Box:
+    line_thickness = 5
+
+    def __init__(self, position, width, height):
+        self.position = pygame.Vector2(position)
+        self.width = width
+        self.height = height
+
+        self.left = self.position.x
+        self.right = self.position.x + self.width
+        self.top = self.position.y
+        self.bottom = self.position.y + self.height
+
+    def update(self, delta):
+        pass
+
+    def draw(self, surf):
+        pygame.draw.rect(surf, BLACK, pygame.Rect(self.left, self.top, self.width, self.height), self.line_thickness)
diff --git a/collision.py b/collision.py
new file mode 100644
index 0000000..2ad00d2
--- /dev/null
+++ b/collision.py
@@ -0,0 +1,5 @@
+def handleBoxCollision(particle, box):
+    if particle.left <= box.left or particle.right >= box.right:
+        particle.velocity.x *= -1
+    if particle.bottom >= box.bottom or particle.top <= box.top:
+        particle.velocity.y *= -1
diff --git a/display.py b/display.py
index 2bf647a..e5fd63e 100644
--- a/display.py
+++ b/display.py
@@ -1,24 +1,33 @@
 from colours import *
+from particle import Particle
+from box import Box
 import pygame
 
-
 pygame.init()
 
 
 class Display:
     WIDTH, HEIGHT = 640, 640
-    DIMENSIONS = pygame.Vector2(WIDTH, HEIGHT)
-    CENTER = pygame.Vector2(WIDTH / 2, HEIGHT / 2)
+    DIMENSIONS = (WIDTH, HEIGHT)
+    CENTER = (WIDTH / 2, HEIGHT / 2)
 
     FPS = 60
+    COLLISION_LAYERS = 4
 
     def __init__(self, window_name="Pygame"):
         self.is_running = False
+
         pygame.display.set_caption(window_name)
 
+        self.collision_objects = {layer: [] for layer in range(self.COLLISION_LAYERS)}
+
+        self.particles = [Particle(self.CENTER, (0, 0.5), (0, 0), 15, self.collision_objects[0])]
+        self.collision_objects[0] += self.particles
+        self.box = Box((0, 0), self.WIDTH, self.HEIGHT)
+        self.collision_objects[0].append(self.box)
+
     def show(self):
         screen = pygame.display.set_mode(self.DIMENSIONS)
-
         clock = pygame.time.Clock()
         delta = 0
         self.is_running = True
@@ -34,5 +43,15 @@ class Display:
             if event.type == pygame.QUIT:
                 self.is_running = False
 
+        self.box.update(delta)
+
+        for particle in self.particles:
+            particle.update(delta)
+
     def draw(self, surf):
         surf.fill(WHITE)
+
+        self.box.draw(surf)
+
+        for particle in self.particles:
+            particle.draw(surf)
diff --git a/main.py b/main.py
index ee74ed5..dc3360a 100644
--- a/main.py
+++ b/main.py
@@ -2,7 +2,7 @@ from display import Display
 
 
 def main():
-    d = Display()
+    d = Display("Collision Simulation")
     d.show()
 
 
diff --git a/particle.py b/particle.py
new file mode 100644
index 0000000..0f71de8
--- /dev/null
+++ b/particle.py
@@ -0,0 +1,43 @@
+import pygame
+from math import copysign
+from colours import *
+from box import Box
+from collision import handleBoxCollision
+
+
+class Particle:
+    speed_limit = 3
+
+    def __init__(self, initial_position, initial_velocity, initial_acceleration, radius, collision_layer):
+        self.position = pygame.Vector2(initial_position)
+        self.velocity = pygame.Vector2(initial_velocity)
+        self.acceleration = pygame.Vector2(initial_acceleration)
+        self.radius = radius
+
+        self.left = self.position.x - self.radius
+        self.right = self.position.x + self.radius
+        self.top = self.position.y - self.radius
+        self.bottom = self.position.y + self.radius
+
+        self.collision_layer = collision_layer
+
+    def update(self, delta):
+        self.velocity.x = min(self.speed_limit, abs(self.velocity.x + self.acceleration.x * delta))\
+                          * copysign(1, self.velocity.x + self.acceleration.x * delta)
+        self.velocity.y = min(self.speed_limit, abs(self.velocity.y + self.acceleration.y * delta))\
+                          * copysign(1, self.velocity.y + self.acceleration.y * delta)
+
+        self.position.x += self.velocity.x * delta
+        self.position.y += self.velocity.y * delta
+
+        self.left = self.position.x - self.radius
+        self.right = self.position.x + self.radius
+        self.top = self.position.y - self.radius
+        self.bottom = self.position.y + self.radius
+
+        for thing in self.collision_layer:
+            if isinstance(thing, Box):
+                handleBoxCollision(self, thing)
+
+    def draw(self, surf):
+        pygame.draw.circle(surf, RED, self.position, self.radius)