Editing and animating text appearance for graphic designs, commercials, etc. remain highly skilled tasks requiring detailed, hands on efforts from artists. Automating these manual workflows requires balancing the competing goals of maintaining legibility and aesthetics of text, while enabling creative expression. Variable fonts, recent parametric extensions to traditional fonts, offer the promise of new ways to ease and automate typographic design and animation. Variable fonts provide custom constructed parameters along which fonts can be smoothly varied. These parameterizations could then potentially serve as high value continuous design spaces, opening the door to automated design optimization tools. However, currently variable fonts are underutilized in creative applications, because artists so far still need to manually tune font parameters. Our work opens the door to intuitive and automated font design and animation workflows with differentiable variable fonts. To do so we distill the current variable font specification to a compact mathematical formulation that differentiably connects the highly non linear, non invertible mapping of variable font parameters to the underlying vector graphics representing the text. This enables us to construct a differentiable framework, with respect to variable font parameters, allowing us to perform gradient based optimization of energies defined on vector graphics control points, and on target rasterized images. We demonstrate the utility of this framework with four applications: direct shape manipulation, overlap aware modeling, physics based text animation, and automated font design optimization. Our work now enables leveraging the carefully designed affordances of variable fonts with differentiability to use modern design optimization technologies, opening new possibilities for easy and intuitive typographic design workflows.

翻译：在平面设计、商业广告等领域中，编辑和动画化文本外观仍是高度专业化的任务，需要艺术家投入大量细致的手动工作。自动化这些手动工作流程需要在保持文本可读性与美学效果，以及实现创意表达之间取得平衡。可变字体作为传统字体的最新参数化扩展，有望为字体设计和动画提供新的简化与自动化途径。可变字体提供了自定义构建的参数，字体可沿这些参数平滑变化。这些参数化随后可能成为高价值的连续设计空间，为自动化设计优化工具打开大门。然而，目前可变字体在创意应用中仍未得到充分利用，因为艺术家仍需手动调整字体参数。我们的工作通过可微分可变字体，为直观且自动化的字体设计与动画工作流程开辟了道路。为此，我们将当前的可变字体规范提炼为一种紧凑的数学表述，该表述可微分地连接了可变字体参数到表示文本的底层矢量图形之间的高度非线性、不可逆映射。这使我们能够构建一个关于可变字体参数的可微分框架，从而允许我们对定义在矢量图形控制点以及目标栅格化图像上的能量函数执行基于梯度的优化。我们通过四个应用展示了该框架的实用性：直接形状操控、重叠感知建模、基于物理的文本动画以及自动化字体设计优化。我们的工作现在使得能够利用可变字体精心设计的可供性，结合可微分性来运用现代设计优化技术，为轻松直观的字体设计工作流程开辟了新的可能性。