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I'm trying to produce the following ellipse as a surface or curve within blender with the following specifications.

The following dimensions, including the position of the origin in x,y,z coordinates will be known. For this image, it will be a flat plane in the x,y direction.

What's the best way or how do you go about coding this?

thanks!

ellipse

some minor clarifications - the width is a + b = 12.

How about if this was the scenario instead, when it's more skewed and doesn't look like a circle?

enter image description here

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2 Answers 2

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I found a solution! Use this code in the blender text editor:

import bpy
import math

#IMPORTANT : set 3d cursor to world origin    
bpy.context.area.spaces[1].cursor_location = (0.0, 0.0, 0.0)

#Add circle curve
bpy.ops.curve.primitive_bezier_circle_add(view_align=False, enter_editmode=False, location=(0, 0, 0), layers=(True, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False))

#define variables
a = 10
b = 2
c = 3 # I use the half of c
d = 5

#Calculate width
width = a + b   #or width = a + d + b?

#Calculate horizontal distance from world origin of c
distance = b / 2

#Calculate height c for the circle
#x^2 + y^2 = 1, see Unit Circle
x = (distance / (width / 2)) * math.pi * 0.5  

cCircle = math.sqrt(1 - x**2)

#now we have to scale the height of the circle, so cCircle becomes c. And give its width.
factor = c / cCircle

bpy.ops.transform.resize(value=((width)/2, factor, 1), constraint_axis=(True, True, False), constraint_orientation='GLOBAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1)

#Calculate location origin
originX = -((width) / 2 ) + b
originY = 0
originZ = 0

#Set 3d Cursor at Origin location
bpy.context.area.spaces[1].cursor_location = (originX, originY, originZ)

#Set origin to 3d cursor
bpy.ops.object.origin_set(type='ORIGIN_CURSOR')

#Move object to world origin
bpy.ops.transform.translate(value=((width/2) - b, 0, 0), constraint_axis=(True, False, False), constraint_orientation='GLOBAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1, release_confirm=True)

#Voila

I hope this helps!

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  • $\begingroup$ hello! thank you for that. It worked great. I had to make a minor modification; from bpy.context.area.spaces[1].cursor_location = (0.0, 0.0, 0.0) to bpy.context.scene.cursor_location = (0.0, 0.0, 0.0) somehow .area.spaces didn't work for me. $\endgroup$
    – Albert
    Commented Nov 14, 2016 at 14:18
  • $\begingroup$ is it possible to achieve the alternative problem? :) $\endgroup$
    – Albert
    Commented Nov 14, 2016 at 14:23
  • $\begingroup$ Yes, but then you must use the bezier curve. $\endgroup$
    – float
    Commented Nov 14, 2016 at 14:29
  • $\begingroup$ You can do it manually or do you need a script for it? $\endgroup$
    – float
    Commented Nov 14, 2016 at 14:30
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Here's an updated version of float's answer. This solution is for Blender versions 2.93, 3.0, 3.1, 3.2, and 3.3

import bpy
import math

win = bpy.context.window
scr = win.screen

def use_temp_override():
    version = bpy.app.version
    major = version[0]
    minor = version[1]
    return not (major < 3 or (major == 3 and minor < 2))

def get_areas(type):
    return [area for area in scr.areas if area.type == type]

def get_regions(areas):
    return [region for region in areas[0].regions if region.type == 'WINDOW']

def execute():

    bpy.context.scene.cursor.location = (0,0,0)

    a = 10
    b = 2
    c = 3
    d = 5

    width = a + b
    distance = b / 2

    x = (distance / (width / 2)) * math.pi * 0.5  

    cCircle = math.sqrt(1 - x**2)
    factor = c / cCircle

    areas  = get_areas('VIEW_3D')

    # ========================================================================================
    # (if) execute using temp override
    # ========================================================================================

    if use_temp_override():

        with bpy.context.temp_override(window=win, area=areas[0], regions=get_regions(areas)[0], screen=scr):

            bpy.ops.view3d.snap_cursor_to_center()
            bpy.ops.curve.primitive_bezier_circle_add(radius=1, enter_editmode=False, align='WORLD', location=(0, 0, 0), scale=(1, 1, 1))
            bpy.ops.transform.resize(value=((width)/2, factor, 1), orient_type='GLOBAL', orient_matrix=((1, 0, 0), (0, 1, 0), (0, 0, 1)), orient_matrix_type='GLOBAL', mirror=False, use_proportional_edit=False, proportional_edit_falloff='SMOOTH', proportional_size=1, use_proportional_connected=False, use_proportional_projected=False)
            bpy.context.scene.cursor.location = (-((width) / 2 ) + b, 0, 0)
            bpy.ops.object.origin_set(type='ORIGIN_CURSOR')
            bpy.ops.transform.translate(value=((width/2) - b, 0, 0), orient_axis_ortho='X', orient_type='GLOBAL', orient_matrix=((1, 0, 0), (0, 1, 0), (0, 0, 1)), orient_matrix_type='GLOBAL', mirror=False, use_proportional_edit=False, proportional_edit_falloff='SMOOTH', proportional_size=1, use_proportional_connected=False, use_proportional_projected=False)

    # ========================================================================================
    # (else) execute using legacy override
    # ========================================================================================        

    else:
        override = {
            'window': win,
            'screen': scr,
            'area': areas[0],
            'region': get_regions(areas)[0],
        }
        bpy.ops.view3d.snap_cursor_to_center(override)
        bpy.ops.curve.primitive_bezier_circle_add(override, radius=1, enter_editmode=False, align='WORLD', location=(0, 0, 0), scale=(1, 1, 1))
        bpy.ops.transform.resize(override, value=((width)/2, factor, 1), orient_type='GLOBAL', orient_matrix=((1, 0, 0), (0, 1, 0), (0, 0, 1)), orient_matrix_type='GLOBAL', mirror=False, use_proportional_edit=False, proportional_edit_falloff='SMOOTH', proportional_size=1, use_proportional_connected=False, use_proportional_projected=False)
        bpy.context.scene.cursor.location = (-((width) / 2 ) + b, 0, 0)
        bpy.ops.object.origin_set(override, type='ORIGIN_CURSOR')
        bpy.ops.transform.translate(override, value=((width/2) - b, 0, 0), orient_axis_ortho='X', orient_type='GLOBAL', orient_matrix=((1, 0, 0), (0, 1, 0), (0, 0, 1)), orient_matrix_type='GLOBAL', mirror=False, use_proportional_edit=False, proportional_edit_falloff='SMOOTH', proportional_size=1, use_proportional_connected=False, use_proportional_projected=False)

print("start ======")
execute()
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