Gradient rings from Python for Designers tutorial

[eduairet]

Hello everyone!!!

I'm attempting to solve the ex­er­cise 14.4 of @roberto-arista 's pythonfordesigners.com/chapters/workbook/ I'm having a problem with my approach, I decided to use circles instead of lines and I couldn't find a way to make a smooth gradient without having a weird hole in the middle of the right top and right bottom blending, here's a photo of it:

# 14.4
def donuts(circSize=10, cnvSize=200):
    
    def intrp(factor, val1, val2):
        return val1 + (val2 - val1) * factor
        
    def intrRgb(factor, col1, col2):
        r = intrp(factor, col1[0], col2[0])
        g = intrp(factor, col1[1], col2[1])
        b = intrp(factor, col1[2], col2[2])
        return r, g, b
        
    def circCoords(radius, circSize=10):
        cirCoords = []
        an = 0
        anMulti = 0
        for i in range(cnvSize+1):
            for j in range(cnvSize):
                cirCoords.append([
                    radius * sin(pi * 2 * an / 360) - halfCirc,
                    radius * cos(pi * 2 * an / 360) - halfCirc
                ])
                an += 360/(cnvSize*cnvSize)
        return sorted(cirCoords)
        
    def mapColors(c1, c2, c3, c4):
        colors = []
        for x in range(cnvSize):
            xFactor = x/cnvSize
            for y in range(cnvSize):
                yFactor = y / cnvSize
                lftClr = intrRgb(yFactor, c4, c1)
                rgtClr = intrRgb(yFactor, c3, c2)
                colors.append(intrRgb(xFactor, lftClr, rgtClr))       
        return colors
    
    halfCirc = circSize/2
    colors = {'lftTop': (1, 0, 0.8), 'rgtTop': (1, 1, 0.3), 'rgtBtm': (1, .8, 0), 'lftBtm': (0, 0.5, 1)} 
    
    colors = mapColors(colors['lftTop'], colors['rgtTop'], colors['rgtBtm'], colors['lftBtm'])
    circles = [circCoords(cnvSize*0.4, circSize), circCoords(cnvSize*0.25, circSize), circCoords(cnvSize*0.1, circSize)]
    
    newPage(cnvSize, cnvSize)
    inc = 0
    for x in range(cnvSize):
        for y in range(cnvSize):
            fill(*colors[inc])
            if x == 0 and y == 0 or x == 0 and y == cnvSize-1 or x == cnvSize-1 and y == 0 or x == cnvSize-1 and y == cnvSize-1:
                oval(x - halfCirc, y - halfCirc, circSize, circSize)
            if y == int(circles[0][inc][1]) + cnvSize/2 - 1 or y == int(circles[0][inc][1]) + cnvSize - 100:
                for circ in circles:
                    with savedState():
                        translate(cnvSize/2, cnvSize/2)
                        oval(circ[inc][0], circ[inc][1], circSize, circSize)
            inc += 1

# Call the function
donuts()

Hope you can help me, feedback on my approach would be great too, thank you!!!!!!!

[frederik]

I think the circCoords is a bit overkill
its creating an circular x, y coordinate while looping over the width and height of the page. You are drawing a lot of ovals

radius = 100
translate(width() *.5, height() *.5)

inSteps = 1
# inSteps = 15

for angle in range(0, 360, inSteps):
    factor = angle / 360 * 2
    if factor > 1:
        factor = 2 - factor    
    
    x = cos(radians(angle)) * radius
    y = sin(radians(angle)) * radius
    
    fill(factor, 0, 1)
    oval(x - 5, y - 5, 10, 10)

[eduairet]

@frederik thank you very much! I'll implement this way