Why is my output just a blank white image? [Python PIL] - python-3.x

Question

I am getting a blank and white image instead of the desired output, help?
from PIL import Image
def draw_nested_rectangles():
height = int(input('Please enter the overall height: '))
width = int(input('Please enter the overall width: '))
size = (width,height)
pic = Image.new('RGB',size,'white')
firstRec(width,height)
secondRec(width,height)
thirdRec(width,height)
fourthRec(width,height)
pic.show()
def firstRec(width,height):
size = (width,height)
pic = Image.new('RGB', size, 'white')
blueProgression = 0
for x in range(width,width):
color = (0,0,blueProgression)
for y in range(height,height):
pic.putpixel((x,y),color)
blueProgression += 5
def secondRec(width,height):
size = (width,height)
pic = Image.new('RGB', size, 'white')
greenProgression = 255
for x in range(int(width*0.15),int(width*0.85)):
color = (0,greenProgression,0)
for y in range(int(height*0.15),int(height*0.85)):
pic.putpixel((x,y),color)
greenProgression -= 5
def thirdRec(width,height):
size = (width,height)
pic = Image.new('RGB', size, 'white')
greenProgression = 255
for x in range(int(width*0.30),int(width*0.70)):
color = (255,0,0)
for y in range(int(height*0.30),int(height*0.70)):
pic.putpixel((x,y),color)
def fourthRec(width,height):
size = (width,height)
pic = Image.new('RGB', size, 'white')
greenProgression = 255
for x in range(int(width*0.45),int(width*0.55)):
color = (255,255,255)
for y in range(int(height*0.45),int(height*0.55)):
pic.putpixel((x,y),color)
I want my output to be four nested triangles the first one being 100% of the width and height (starting off black on the right side and gradually increasing to blue) and the second being nested in the first being 70% of the original width and height (starting off black on the left side and gradually increasing to green) and the third being nested in and being 40% the original (pure red) while the last is nested in and being 10% (pure white)

Answer 1

TRY:-
from PIL import Image
def draw_nested_rectangles():
global pic
height = int(input('Please enter the overall height: '))
width = int(input('Please enter the overall width: '))
size = (width,height)
pic = Image.new('RGB', size, 'white')
firstRec(width, height)
secondRec(width, height)
thirdRec(width, height)
fourthRec(width, height)
pic.show()
def firstRec(width,height):
global pic
size = (width,height)
blueProgression = 0
for x in range(width,width):
color = (0,0,blueProgression)
for y in range(height,height):
pic.putpixel((x,y),color)
blueProgression += 5
def secondRec(width,height):
global pic
size = (width,height)
greenProgression = 255
for x in range(int(width*0.15),int(width*0.85)):
color = (0,greenProgression,0)
for y in range(int(height*0.15),int(height*0.85)):
pic.putpixel((x,y), color)
greenProgression -= 5
def thirdRec(width,height):
global pic
size = (width,height)
greenProgression = 255
for x in range(int(width*0.30),int(width*0.70)):
color = (255,0,0)
for y in range(int(height*0.30),int(height*0.70)):
pic.putpixel((x,y),color)
def fourthRec(width,height):
global pic
size = (width,height)
greenProgression = 255
for x in range(int(width*0.45),int(width*0.55)):
color = (255,255,255)
for y in range(int(height*0.45),int(height*0.55)):
pic.putpixel((x,y),color)
pic = 0
draw_nested_rectangles()
REASON FOR UNDESIRABLE OUTPUT:-
The reason why you were getting a blank image, rather then the one you expected is because, you were creating a separate pic image object inside each function, due to which all the function were working on separate image objects rather then a single one.
FIX:-
In order to get the desired output, you have to define the pic variable as global, inside each function that want to use it, by using the syntax global pic
SAMPLE INPUT:-
Please enter the overall height: 500
Please enter the overall width: 500
SAMPLE OUTPUT:-