When it comes to rendering convincing crystal or glass surfaces, most developers immediately think of ray tracing, and for good reason. Ray tracing allows us to simulate light bouncing and refracting through translucent materials with stunning realism. However, this technique comes at a high computational cost and is still impractical for most mobile devices and lightweight games. That said, it’s only a matter of time before such effects become mainstream, even on entry-level GPUs.
But what if you want that crystal-like look today, without relying on expensive rendering techniques?
The answer lies in shader tricks.
In the following example, we’ve combined multiple shader techniques to simulate the illusion of refraction, reflection, and glitter - without a single ray being traced.
As you can see, the effect is broken into multiple layers, each carefully crafted to fake complex lighting behavior:
- Refraction: Rather than calculating how light bends through the surface, we simply distort the UV coordinates based on the camera view direction and a depth approximation. This gives the illusion of bending light as it passes through the crystal.
- Reflection: Instead of environment mapping or screen-space reflections, we use a matcap texture. By adding a subtle glitter based on the normals' divergence, we enhance the surface detail. This is rendered in a second pass to give it extra depth.
Despite these being “fakes,” the final result is surprisingly convincing:
Learn How It's Done, Step-by-Step
This technique (and many more like it) will be fully covered in Chapter 4 of the upcoming update to the Godot Shaders Bible, our in-depth book for artists and developers working with Godot.
Whether you’re new to shaders or looking to push the limits of what Godot can render, this book is designed to help you master everything from surface tricks like this one to complex lighting models, all explained with real examples and code you can use from a math perspective.
👉 Get the book in development now at a discount and be among the first to receive the new chapters as they’re released.
Jettelly wishes you success in your professional career!
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Would you like to learn more?
We invite you to explore "The Godot Shaders Bible", a comphensive book on the concepts and fundamentals seen in this post.
Other posts that might interest you.
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This tutorial will guide you through the process of creating a UI blur in Unity using Shader Graph, a node-based shader creation tool. -
Shader Graph is great for multi-platform games, but for advanced control and efficiency, learning HLSL and ShaderLab is key. Explore these techniques in depth with the Unity Shaders Bible! -
Sprite Masks on 3D Quads? Not quite, but with the power of shaders, you can create a similar effect!
