This Inkscape extension transforms an object along the x-axis and/or y-axis. The bounding box remains unchanged. Points near the center of the object move to create the illusion of a curved surface. When selecting an x-axis distortion, points move left, if you choose an exponent > 1, and right if the exponent is < 1. An exponent of 1.0 does exactly nothing. An optional (left side) padding can be applied to soften the effect. When selecting an y-axis distortion, points move up, if the exponent is > 1 or down when < 1. Padding is applied on top.
This can be used in combination with the bend path effect to create a cone projection that retains aspect ratio.
Caution: Finding correct parameters for e.g. a cone projection is left as an exercise to the user.
