Radial gradients

[Fatesight]

Godot version:
3.0.2

OS/device including version:
Irrelevant.

Issue description:
Currently there seems to be no way to programmatically create radial gradients. Having to create them in an external tool and import them as textures is not only inconvenient, but also makes it impossible to effectively manipulate them at runtime.

[Zylann]

With a bit of work, it's possible to make them programmatically by generating a triangle strip polygon with appropriate vertex colors. Or easier, a shader with a GradientTexture as parameter (or a few colors) and a bit of UV math magic:

RadialGradient.zip

[regakakobigman]

This would still be really useful. Radial gradients would be perfect for 2D lights.

It is not very convenient to open up an image editor just to edit a gradient. Every image editor handles them differently, too. It would be easier if these could be edited in the editor

[Maujoe]

For all those looking for a temporary solution:

https://github.com/Maujoe/godot-custom-gradient-texture
I have created a custom resource script as temporary workaround to create different gradient types it's also in the asset library so you can access it inside godot.

[Calinou]

Superseded by godotengine/godot-proposals#1677.