# Example for in-class assignment - bounce a triangle
import sys, random, time, math
from OpenGL.GLUT import *
from OpenGL.GL import *
from OpenGL.GLU import *

class Triangle:
    def __init__(self):
        self.startTime = time.time()
        self.x = random.uniform(-1,1)
        self.y = -1
        self.rgb = [random.uniform(0,1), random.uniform(0,1), random.uniform(0,1)]
    def update(self, t):
        self.y = abs(math.sin(t - self.startTime)) * 2 - 1
    def draw(self):
        glColor3fv(self.rgb)
        glBegin(GL_TRIANGLES)
        glVertex2f(self.x-0.1, self.y-0.1)
        glVertex2f(self.x+0.1, self.y-0.1)
        glVertex2f(self.x, self.y+0.1)
        glEnd()

triangles = [Triangle()]

def draw():
    glClearColor(0,0,0,0)
    glClear(GL_COLOR_BUFFER_BIT)
    for t in triangles:
        t.draw()
    glutSwapBuffers()

def keyboard(key, x, y):
    if key == chr(27):
        sys.exit(0)
    elif key == ' ':
        triangles.append(Triangle())

def update(v):
    glutTimerFunc(16, update, 0)
    currentTime = time.time()
    for t in triangles:
        t.update(currentTime)
    glutPostRedisplay()

glutInit([])
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB)
glutInitWindowSize(500, 500)
glutInitWindowPosition(0,0)
glutCreateWindow(sys.argv[0])
glutDisplayFunc(draw)
glutKeyboardFunc(keyboard)
glutTimerFunc(0, update, 0)
glutMainLoop()