HLSL & Blueprints: Create Real-Time Audio Visualizers in Unreal 5.6

Discover how to create dynamic, sound-reactive audio bars in Unreal Engine 5.6. This tutorial uses HLSL shaders and Blueprints to build real-time visualizers for music, VFX, or interactive experiences.

Unreal Engine 5.6 opens up incredible possibilities for dynamic visuals, and few things are as engaging as graphics that react to sound. In a fantastic tutorial, the talented creator renderBucket walks us through the process of building an “Easy Sound Reactive Material” – essentially, an audio bar visualizer that responds to music in real-time. This guide is perfect for anyone looking to dive into technical art, shader programming, or simply enhance their Unreal Engine projects with interactive audio-driven effects.

renderBucket’s approach combines the power of HLSL (High-Level Shading Language) for custom material logic with the flexibility of Unreal Engine Blueprints, offering a robust solution for real-time audio visualization. Let’s break down the key steps he outlines in the video.

Crafting the Core Material (MC_audiobar)

The journey begins in the Material Editor by creating a new material, MC_audiobar. The core of this material is a Custom node, where the HLSL magic happens. This node requires two crucial inputs:

• UV: Connected to a TextureCoordinate node, which provides the coordinates for our visual bar.
• audio level: Initially a placeholder constant, but later converted into a Material Parameter named “input level” for external control. The output of this custom node feeds directly into the material’s Emissive Color.

Inside the Custom node, the HLSL code is surprisingly concise yet powerful:

1. A float volume variable is declared, assigned the audio level, and then passed through saturate() to clamp its value between 0 and 1. This prevents any visual glitches from out-of-range values.
2. A float3 bar variable defines the color of our visualizer. The creator uses lerp (linear interpolation) between two colors (e.g., green and red) based on UV.y, creating a vertical gradient. Experimenting with the color order here can change the gradient’s direction.
3. To make the bar react to sound, the bar color is multiplied by a step() function: step(1 - UV.y, volume). This is the clever part! The step function acts as a mask, revealing more of the bar as the volume increases and hiding it when the volume is low. This creates the iconic rising and falling effect of an audio visualizer.

This video is a testament to renderBucket’s skill in demystifying shader programming. For those interested in diving deeper into HLSL, he also offers an excellent HLSL Tutorial Series.

Bringing it to Life with Blueprints

With the material ready, the next step is to create an Actor Blueprint (e.g., BP_audio_source_00001) to house the audio source and display the material. Inside this Blueprint:

1. A Plane component is added, serving as the mesh to display our MC_audiobar material. The creator suggests rotating it appropriately.
2. An Audio component is added, assigned a looping sound (preferably a custom Sound Cue), and its attenuation settings are adjusted to control how the sound is heard in the scene.

The real-time connection between the audio’s loudness and the material happens in the Blueprint’s Event Graph:

1. An OnAudioSingleEnvelopeValue event is added for the Audio component. This event continuously provides the Envelope Value, representing the audio’s real-time loudness.
2. From this event, a Create Dynamic Material Instance node is connected, targeting the Plane component and using MC_audiobar as the source. Creating a dynamic instance is crucial because it allows us to modify material parameters during runtime.
3. Following this, a Set Scalar Parameter Value node is connected. Its Parameter Name is set to “input level” (matching our material parameter), and its Value is directly linked to the Envelope Value from the audio event. The tutorial also suggests an optional multiplication of the Envelope Value (e.g., by 2) to exaggerate the visual movement, making the bars more dynamic.

After compiling and saving the Blueprint, placing it in the scene and starting the simulation will bring your audio bar to life, reacting dynamically to the playing sound. This elegant solution demonstrates how Unreal Engine’s built-in audio analysis can be directly hooked into custom visual effects.

Why This Matters for Your Projects

The technique renderBucket showcases is incredibly versatile. Beyond simple music visualization, these sound-reactive materials can be used for:

• Interactive Environments: Imagine objects in your game world pulsating with the game’s soundtrack or reacting to player actions.
• VFX: Create dynamic particle effects, glowing elements, or environmental shaders that respond to in-game sounds like explosions or spells.
• Live Events & Installations: For real-time visual performances, this method offers a straightforward way to create captivating audio-driven graphics.

The ability to create such effects with relatively simple HLSL and Blueprint logic highlights the power and flexibility of Unreal Engine’s material system. The creator’s method is efficient and provides a solid foundation for more complex audio-reactive systems.

renderBucket consistently delivers high-quality content, and his other tutorials, such as Animated WPO & Normal Map Generation, Realistic Interactive Water in 5 Minutes, and Realistic Ice & Gemstones Materials, are also worth exploring for anyone serious about technical art in Unreal Engine. If you found this tutorial helpful and want to support the creation of more valuable content, consider checking out his Patreon or joining his Discord community.

By following this tutorial, you’ll gain a deeper understanding of how to bridge the gap between audio and visuals in Unreal Engine, opening up a new dimension for your creative projects.

Source:
renderBucket – Unreal Engine 5.6,– Easy Sound Reactive Material (Audio Bar / Visualizer Tutorial)