Developing Interactive Dissolve Effects

In this lesson, you will learn how to create a procedural dissolve effect that allows you to vanish game objects smoothly by using a noise texture driven by a global shader property.

The Logic of the Dissolve

At its core, a dissolve effect is a mathematical comparison. We use a Noise Node (typically Perlin or Simplex noise) to generate a grayscale pattern across the surface of an object. We then use an Alpha Clip Threshold node to discard pixels where the noise value is lower than a specific "cutoff" value.

By feeding a float property into this cutoff, we can control how much of the object remains visible. When the cutoff is 0, the entire object is rendered; when it is 1, the entire object is clipped away.

Implementing the Shader Graph

1. Noise Input: Create a Sample Texture 2D node using a grayscale noise texture.
2. Global Property: Create a Float property in the Blackboard (e.g., _DissolveAmount) and ensure it is exposed.
3. The Comparison: Connect your noise texture output and the _DissolveAmount property to a Subtract node. Feed the result into the Alpha Clip Threshold input of your Master Stack (ensure your material is set to Transparent or Alpha Clipping mode).

To make this interactive via script, you can access the material's property using Material.SetFloat. Because we are using a global property or a material instance, we can animate this value using a Tween or an AnimationCurve to create a smooth fade:

// Example of triggering the dissolve via script
public void TriggerDissolve(float targetValue) {
    renderer.material.SetFloat("_DissolveAmount", targetValue);
}

Adding Polish

To elevate the effect, use a Step node to create a sharp line at the transition edge. By plugging the output of the Step into an Emission node multiplied by a color, you can create a "burning" effect where the edges glow as the object disappears. This technique effectively hides the geometry as it transitions from fully visible to fully invisible, creating a clean, procedural transition suitable for spawning, death animations, or teleportation.

Key Takeaway: By comparing a noise texture against an animated float property in the Alpha Clip Threshold, you can procedurally vanish any geometry with precise, artist-controlled results.