"""
sohCahToa01.py
Eric Pavey - 2009-08-08
Understand how sine, cosine, and tangent work in relationship to
the opposite, adjacent, and hypotenuse triangle sides.
"""

#--------------
# imports & initis
import math
import sys
import pygame
from pygame.locals import *
pygame.init()

#--------------
# constants & global vars
WIDTH = 800
HEIGHT = WIDTH
FRAMERATE = 60
# size our circle is relative to screen size
CIRCLESIZE = .75

font16 = pygame.font.SysFont("courier", 16)
circleRadius = int(WIDTH/2 * CIRCLESIZE)

#-------------
# screen setup
screen = pygame.display.set_mode((WIDTH, HEIGHT))
screenRect = screen.get_rect()
pygame.display.set_caption("sohCahToa01.py")
clock = pygame.time.Clock()

#-------------
# background setup:
background = screen.copy()
# draw the inner circle:
pygame.draw.circle(background, Color("red"), screenRect.center, 4, 2)
# draw the outer circle:
pygame.draw.circle(background, Color("red"), screenRect.center, circleRadius, 2)
lblDirections = font16.render("Press space to pause...", 1, Color("white"))
background.blit(lblDirections, (8,8))

#---------
# functions

def lerp2D(p1, p2, amt):
    # return back a point some percentage between two other points.
    # amt : 0.0->1.0
    x = p1[0] + (p2[0] - p1[0]) * amt
    y = p1[1] + (p2[1] - p1[1]) * amt
    return [x,y]
def degreesToRadians(deg):
    # Convert degrees to radians, returns float
    return (deg * math.pi) / 180.0

def degreesToPi(deg):
    return deg / 180.0

def distanceBetweenPoints2D(a, b):
    # return the distance between two points.  Points are tuple (#,#)
    return math.sqrt(abs(pow(b[0]-a[0], 2) + pow(b[1]-a[1], 2)))

def drawTriangle(radians):
    hypCol = Color("green")
    oppCol = Color("pink")
    adjCol = Color("orange")

    cx, cy = screenRect.center
    # define the end point of our radius \ hypotenuse:
    x = math.cos(radians) * circleRadius + screenRect.center[0]
    # Reverse Y, since the coordinate system used for the math is opposite
    # to that as used in pygame:
    y = -math.sin(radians) * circleRadius + screenRect.center[1] 

    # draw hypotenuse:
    pygame.draw.line(screen, hypCol, (cx, cy), (x,y))
    hypLen = distanceBetweenPoints2D((cx, cy), (x,y)) / circleRadius
    hypMid = lerp2D((cx, cy), (x,y), .75)
    # hypotenuse text:
    hypText = "hyp len: %.2f" % hypLen
    hypLbl = font16.render(hypText, 1, hypCol)
    screen.blit(hypLbl, (hypMid[0]-hypLbl.get_width()/2, hypMid[1]))    

    # draw opposite:
    pygame.draw.line(screen, oppCol, (x,cy), (x,y))
    oppLen = distanceBetweenPoints2D((x,cy), (x,y)) / circleRadius
    oppMid = lerp2D((x,cy), (x,y), .25)    
    # opposite text:
    oppText = "opp len: %.2f" % oppLen
    oppLbl = font16.render(oppText, 1, oppCol)
    screen.blit(oppLbl, (oppMid[0]-oppLbl.get_width()/2, oppMid[1]))   

    # draw adjacent:
    pygame.draw.line(screen, adjCol, (cx, cy), (x,cy))
    adjLen = distanceBetweenPoints2D((cx, cy), (x,cy)) / circleRadius  
    adjMid = lerp2D((cx,cy), (x,cy), .5) 
    # adjacent text:
    adjText = "adj len: %.2f" % adjLen
    adjLbl = font16.render(adjText, 1, adjCol)
    screen.blit(adjLbl, (adjMid[0]-adjLbl.get_width()/2, adjMid[1]-20))      

    # calculate values from lengths:
    sin = 0.0
    try:
        sin = oppLen/hypLen
    except ZeroDivisionError:
        pass
    cos = 0.0
    try:
        cos = adjLen/hypLen
    except ZeroDivisionError:
        pass
    tan = 0.0
    try:
        tan = oppLen/adjLen
        # hack:
        #if math.pi > radians > math.pi/2 or math.pi*1.5 < radians < math.pi*2:
        #    tan *= -1
    except ZeroDivisionError:
        pass        

    # print text at bottom of screen:
    hypTxt = font16.render("hyp", 1, hypCol) 
    oppTxt = font16.render("opp", 1, oppCol)
    adjTxt = font16.render("adj", 1, adjCol)
    hypNum = font16.render("%.2f"%hypLen, 1, hypCol)
    oppNum = font16.render("%.2f"%oppLen, 1, oppCol)
    adjNum = font16.render("%.2f"%adjLen, 1, adjCol)
    col = (128, 187, 248, 318)

    sohTxt = "(SOH) sin =     /     =      /      = %.2f" % sin  
    sohLbl = font16.render(sohTxt, 1, Color("white"))    
    screen.blit(sohLbl, (8, HEIGHT-60))
    screen.blit(oppTxt, (col[0], HEIGHT-60))
    screen.blit(hypTxt, (col[1], HEIGHT-60))
    screen.blit(oppNum, (col[2], HEIGHT-60))
    screen.blit(hypNum, (col[3], HEIGHT-60))

    cahTxt = "(CAH) cos =     /     =      /      = %.2f" % cos
    cahLbl = font16.render(cahTxt, 1, Color("white"))    
    screen.blit(cahLbl, (8, HEIGHT-40))  
    screen.blit(adjTxt, (col[0], HEIGHT-40))
    screen.blit(hypTxt, (col[1], HEIGHT-40))
    screen.blit(adjNum, (col[2], HEIGHT-40))
    screen.blit(hypNum, (col[3], HEIGHT-40))    

    toaTxt = "(TOA) tan =     /     =      /      = %.2f" % tan
    toaLbl = font16.render(toaTxt, 1, Color("white"))    
    screen.blit(toaLbl, (8, HEIGHT-20))    
    screen.blit(oppTxt, (col[0], HEIGHT-20))
    screen.blit(adjTxt, (col[1], HEIGHT-20))
    screen.blit(oppNum, (col[2], HEIGHT-20))
    screen.blit(adjNum, (col[3], HEIGHT-20))      

#------------
# main loop  
def main():
    print "Running Python version:", sys.version
    print "Running PyGame version:", pygame.ver
    looping = True
    pause = 0
    degrees = 0.0
    while looping:
        if degrees > 360:
            degrees = 0.0
        # detect for events
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                looping = False
            elif event.type == KEYDOWN:
                if event.key == K_ESCAPE:
                    looping = False
                if event.key == K_SPACE:
                    pause = abs(pause-1)                   

        screen.blit(background, (0,0))
        drawTriangle(degreesToRadians(degrees))

        # draw the text for degrees, radians, and pi
        lblText = "deg: %03d, rad %.2f, pi %.02f" %(degrees, degreesToRadians(degrees), degreesToPi(degrees))
        lblDegrees = font16.render(lblText, 1, Color("white"))
        screen.blit(lblDegrees, screenRect.center)
        # draw representation arc:
        arcRec = pygame.Rect((screenRect.center[0]-WIDTH/16, screenRect.center[1]-WIDTH/16), (WIDTH/8,WIDTH/8))
        pygame.draw.arc(screen, Color("white"), arcRec, 0, degreesToRadians(degrees))        

        # update our display to screen:
        pygame.display.update()
        clock.tick(FRAMERATE)
        if not pause:
            degrees += .25

if __name__ == "__main__":
    main()