Flutter Shaders: An Introduction. A shader is a program executed by the… | by Karthik Ponnam | Medium

A shader is a program executed by the GPU and usually authored in a language GLSL. User written shaders can be added to Flutter projects using the FragmentProgram API. You can use custom shaders to provide rich graphical effects beyond those provided by the Flutter SDK
What are Shaders?

A shader is a small program that runs on the graphics processing unit (GPU) of your device. It allows you to write custom graphics and animations by manipulating the colors and positions of individual pixels on the screen. Shaders can be used to create a wide range of effects, from simple color transformations to complex animations and particle systems.
Using Shaders in Flutter

Flutter provides two main classes for working with shaders: ShaderMask and CustomPaint. The ShaderMask class allows us to apply a shader to a widget, while the CustomPaint class allows us to render a custom graphic using a Paint object and a Canvas.

To use shaders in Flutter, we first need to create a Paint object with a shader. The shader can be created using the Shader.linearGradient method, which creates a linear gradient shader. Here's an example:

https://gist.github.com/ponnamkarthik/bdd0897948f9cf8a07cb9343cc6d6df8#file-paint-dart

Next, we can use this Paint object to draw a custom graphic using the CustomPaint widget:

https://gist.github.com/ponnamkarthik/be0a61b32e3194831b9d66e842df6a8a#file-custom_paint-dart

Now we create MyPainter class which is a custom painter that extends the CustomPainter class and implements the paint method, which is called whenever the widget needs to be repainted. In this method, we use the Canvas object to draw our custom graphic using the Paint object:

https://gist.github.com/ponnamkarthik/9356f700123ce14defe9cf30bef7b94c#file-mypainter-dart

Conclusion

In Flutter, we can create truly amazing and interactive user experiences by rendering custom graphics and animations using shaders. Shaders are a powerful tool that allow us to bring our creative ideas to life, whether it’s a simple color change or a complex animation. In this article, we explored the basic use of shaders in Flutter without any custom glsl code.
Next Step

In Next article we will see how we can take an existing shader for shadertoy.com and render it in our flutter app.