How to use shaders to make "wave" effects with SwiftUI

To create a "wave" effect using shaders in SwiftUI, you can follow the steps outlined in the session Create custom visual effects with SwiftUI. Here's a summary of the process:

1. Define the Shader Function: Write a shader function in a Metal file. For a ripple effect, you might call this function ripple. This function will take arguments such as the touch position and the layer content, and it will calculate the distortion for each pixel based on these inputs.

2. Implement the Shader in SwiftUI: Create a view modifier in SwiftUI that will use this shader. This modifier, which you might call RippleModifier, will expose the shader's parameters to SwiftUI and apply the shader to the view's content.

3. Drive the Animation: Since shaders do not have a concept of time, you need to drive the animation from SwiftUI. You can do this by creating another view modifier, such as RippleEffect, which animates the elapsed time and updates the shader parameters accordingly.

4. Debug and Fine-Tune: Use a debug UI to experiment with different parameter values and fine-tune the effect. This allows you to scrub through the animation interactively and adjust the parameters to achieve the desired visual effect.

For a detailed walkthrough, you can watch the relevant part of the session Create custom visual effects with SwiftUI (21:48).

Relevant Sessions

• Create custom visual effects with SwiftUI

Chapter Markers for the Session

• 0 = Introduction
• 89 = Scroll effects
• 381 = Color treatments
• 550 = View transitions
• 769 = Text transitions
• 1180 = Metal shaders
• 1528 = Next steps