Pillow new RGB screen not generating - python-imaging-library

Question

I built a test program using import PIL.imagedraw etc etc and was able to use the draw.line command to draw various lines. All good. In a new program I added new code which built a matrix list of x/y/z points (and cosine/sine expressions with math.lib), an input command for some variables, and then the draw.line command as in the previous code, but now the RGB window is not showing at all. The program doesn’t end and gives no errors. (Pythonista on iOS iPad Pro)
The test program, a noob attempt at perspective projection (which works as expected):
import PIL.ImageDraw as ImageDraw,PIL.Image as Image, PIL.ImageShow as ImageShow
im = Image.new("RGB", (1200,800))
draw = ImageDraw.Draw(im)
GL_z = 0
PP_y = 0
SP_x = 300
SP_y = -400
SP_z = 600
org=600
answer=0
width=100
depth=500
height=500
SP_z1=SP_z+height
px_1 = org
py_1 = org
px_2 = org+90
py_2 = 50 + org
px_3 = -160 + org
py_3 = 550 + org
px_4 = -250 + org
py_4 = 500+org
while answer==0:
SP_z1=SP_z-height
px1_1 = ((px_1 - SP_x)/(py_1 - SP_y))*(py_1 - PP_y)
px1_2 = ((px_2 - SP_x)/(py_2 - SP_y))*(py_2 - PP_y)
px1_3 = ((px_3 - SP_x)/(py_3 - SP_y))*(py_3 - PP_y)
px1_4 = ((px_4 - SP_x)/(py_4 - SP_y))*(py_4 - PP_y)
py1_1 = ((SP_z-GL_z)/(py_1-SP_y))*(py_1-PP_y)
py1_2 = ((SP_z-GL_z)/(py_2-SP_y))*(py_2-PP_y)
py1_3 = ((SP_z-GL_z)/(py_3-SP_y))*(py_3-PP_y)
py1_4 = ((SP_z-GL_z)/(py_4-SP_y))*(py_4-PP_y)
py1_5 = ((SP_z1-GL_z)/(py_1-SP_y))*(py_1-PP_y)
py1_6 = ((SP_z1-GL_z)/(py_2-SP_y))*(py_2-PP_y)
py1_7 = ((SP_z1-GL_z)/(py_3-SP_y))*(py_3-PP_y)
py1_8 = ((SP_z1-GL_z)/(py_4-SP_y))*(py_4-PP_y)
px1_1old = px1_1
px1_2old = px1_2
px1_3old = px1_3
px1_4old = px1_4
py1_1old = py1_1
py1_2old = py1_2
py1_3old = py1_3
py1_4old = py1_4
py1_5old = py1_5
py1_6old = py1_6
py1_7old = py1_7
py1_8old = py1_8
SP_yold = SP_y
draw.line((0,SP_y,1200,SP_y),fill=(255,255,255))
draw.line((px1_1,py1_1,px1_2,py1_2),fill=(0,0,255))
draw.line((px1_2,py1_2,px1_3,py1_3),fill=(0,255,0))
draw.line((px1_3,py1_3,px1_4,py1_4),fill=(255,255,255))
draw.line((px1_4,py1_4,px1_1,py1_1),fill=(100,255,0))
draw.line((px1_1,py1_1,px1_1,py1_5),fill=(255,255,255))
draw.line((px1_1,py1_5,px1_2,py1_6),fill=(255,255,255))
draw.line((px1_2,py1_6,px1_3,py1_7),fill=(255,255,255))
draw.line((px1_3,py1_7,px1_4,py1_8),fill=(255,255,255))
draw.line((px1_4,py1_8,px1_4,py1_4),fill=(150,150,0))
#draw.line((px1_1,py1_1,px1_2,py1_2),fill=(255,255,255))
#draw.line((px1_2,py1_2,px1_3,py1_3),fill=(255,255,255))
#draw.line((px1_3,py1_3,px1_4,py1_4),fill=(255,255,255))
#draw.line((px1_4,py1_4,px1_1,py1_1),fill=(255,255,255))
im.show()
move = input("''")
if move == "w":
SP_y += 50
if move == "s":
SP_x -= 50
if move == "z":
SP_y -= 50
if move == "a":
SP_x += 50
if move == "-":
SP_z -= 50
if move == "=":
SP_z += 50
draw.line((0,SP_yold,1200,SP_yold),fill=(0,0,0))
draw.line((px1_1old,py1_1old,px1_2old,py1_2old),fill=(0,0,0))
draw.line((px1_2old,py1_2old,px1_3old,py1_3old),fill=(0,0,0))
draw.line((px1_3old,py1_3old,px1_4old,py1_4old),fill=(0,0,0))
draw.line((px1_4old,py1_4old,px1_1old,py1_1old),fill=(0,0,0))
draw.line((px1_1old,py1_1old,px1_1old,py1_5old),fill=(0,0,0))
draw.line((px1_1old,py1_5old,px1_2old,py1_6old),fill=(0,0,0))
draw.line((px1_2old,py1_6old,px1_3old,py1_7old),fill=(0,0,0))
draw.line((px1_3old,py1_7old,px1_4old,py1_8old),fill=(0,0,0))
draw.line((px1_4old,py1_8old,px1_4old,py1_4old),fill=(0,0,0))
And this is the code that refuses to draw anything:
import math
import decimal
decimal.getcontext().prec = 6
import PIL.ImageDraw as ImageDraw,PIL.Image as Image, PIL.ImageShow as ImageShow
im = Image.new("RGB", (1200,800))
draw = ImageDraw.Draw(im)
PP_y = 0
SP_x = 300
SP_y = -400
SP_z = 600
org=600
answer=0
dims=[]
for i in range (1, 5):
dim = int(input())
dims.append(dim)
dims[3] = (dims[3]*math.pi)/180
obj1 = [[1,2,3],[4,5,6],[7,8,9],[10,11,12],[13,14,15],[16,17,18],[19,20,21],[22,23,24]]
y1 = [0,0,0,0,0,0,0,0]
y2 = [0,0,0,0,0,0,0,0]
y3 = [0,0,0,0,0,0,0,0]
x1 = [0,0,0,0,0,0,0,0]
z1 = [0,0,0,0,0,0,0,0]
ymod = [0,0,0,0,0,0,0,0]
xmod = [0,0,0,0,0,0,0,0]
obj1[0]=[0,0,0]
obj1[1]=[dims[0] * math.cos(dims[3]),dims[0] * math.sin(dims[3]),0]
obj1[2]=[obj1[1][0] - (dims[1] * math.sin(dims[3])),obj1[1][1] + (dims[1] * math.cos(dims[3])),0]
obj1[3]=[dims[1] * math.sin(dims[3]),dims[1] * math.cos(dims[3]),0]
obj1[4]=[0,0,dims[2]]
obj1[5]=[dims[0] * math.cos(dims[3]),dims[0] * math.sin(dims[3]),dims[2]]
obj1[6]=[obj1[1][0] - (dims[1] * math.sin(dims[3])),obj1[1][1] + (dims[1] * math.cos(dims[3])),dims[2]]
obj1[7]=[dims[1] * math.sin(dims[3]),dims[1] * math.cos(dims[3]),dims[2]]
for i in range (0,7):
y1[i]=obj1[i][1]-PP_y
y2[i]=obj1[i][1]-SP_y
y3[i]=y1[i]/y2[i]
x1[i]=obj1[i][0]-SP_y
z1[i]=obj1[i][2]-SP_z
obj1[i][0]=obj1[i][0] - (x1[i] * y3[i])
obj1[i][2]=obj1[i][2] - (z1[i] * y3[i])
#print(dims)
#print(obj1)
#print(y1,y2,y3,x1,z1,xmod,ymod)
while (True):
draw.line((obj1[0][0],obj1[0][2],obj1[1][0],obj1[1][2]),fill=(255,255,255))

Answer 1

Ah found the error, left out im.show(). Pretty fundamental…
reference
https://pillow.readthedocs.io/en/stable/reference/Image.html