ManimCommunity/manim

VMobject inaccurately attributes width/height attrs to its bézier control points

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#3,619 创建于 2024年2月15日

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 (0 评论) (0 反应) (0 负责人)Python (17,820 star) (1,378 fork)batch import
good first issueissue:bug

描述

Description of bug / unexpected behavior

The VMobject width/height attributes are calculated using the points array which is actually the control points for the quadratic bézier curves. This is not very intuitive behavior for end-users.

Expected behavior

The VMobject width/height attributes should indicate the width/height of the physical curve, respectively.

How to reproduce the issue

class TestFail(Scene):
  def construct(self):
    c = Circle().scale(3)
    c.rotate(30*DEGREES)
    radius = c.width / 2
    l = Line().set_length(radius * 2).move_to(c)

    self.add(c, l)

image

Additional media files

https://discord.com/channels/581738731934056449/976376734935048223/1207665909871677500

Additional comments

Possibly related to this issue: #3344 This may be helpful for anyone fixing this issue in the future: https://stackoverflow.com/questions/2587751/an-algorithm-to-find-bounding-box-of-closed-bezier-curves

贡献者指南

技术栈
python
领域
backend
议题类型
bug
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
3
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
1-2 days
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
fresh
清晰度议题是否清楚说明期望改动、验收标准和下一步。
clear
前置要求
PythonManimBézier curves
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
65
研究方向
Investigate the VMobject class, specifically the width and height properties. The current implementation uses self.points which are control points. Refer to the StackOverflow link provided for an algorithm to compute the actual bounding box of a closed Bezier curve. Also examine the related issue #3344 for context. The fix should modify the width/height properties to return the actual bounding box dimensions of the rendered curve.
VMobject inaccurately attributes width/height attrs to its bézier control points · ManimCommunity/manim#3619 | Good First Issue