Babylon.js Shaders — Custom GLSL Shader Programming
In this tutorial, you will learn about Babylon.js Shaders. We cover key concepts, practical examples, and best practices to help you master this topic.
Babylon.js shaders enable custom GLSL vertex and fragment programs for creating unique visual effects like distortion, glow, and procedural textures.
What You'll Learn
By the end of this guide, you will create ShaderMaterial with custom vertex and fragment shaders, pass uniforms and attributes, build post-Process shader pipelines, use time-based uniform animation, and debug shader compilation errors.
Basic ShaderMaterial
var shaderMat = new BABYLON.ShaderMaterial('shader', scene, {
vertex: 'custom',
fragment: 'custom',
attributes: ['position', 'normal', 'uv'],
uniforms: ['worldViewProjection', 'time']
});
// In shaders/custom.vertex.glsl
// In shaders/custom.fragment.glsl
Inline Shader
var vertexSrc = 'precision highp float; attribute vec3 position; uniform mat4 worldViewProjection; void main() { gl_Position = worldViewProjection * vec4(position, 1.0); }';
var fragmentSrc = 'precision highp float; uniform float time; void main() { gl_FragColor = vec4(abs(sin(time)), 0.2, 0.4, 1.0); }';
BABYLON.Effect.ShadersStore['customVertexShader'] = vertexSrc;
BABYLON.Effect.ShadersStore['customFragmentShader'] = fragmentSrc;
var mat = new BABYLON.ShaderMaterial('shader', scene, {
vertex: 'customVertex',
fragment: 'customFragment',
attributes: ['position'],
uniforms: ['worldViewProjection', 'time']
});
Post-Process Shader
var postProcess = new BABYLON.PostProcess('blur', 'blur', ['screenSize'], null, 1.0, camera);
// Implement in shaders/blur.fragment.glsl
Common Mistakes
1. Missing Uniforms
Accessing undeclared uniforms causes shader compilation errors. Declare all uniforms in the ShaderMaterial config.
2. Wrong Precision
Common error: precision highp float; must be the first line. Missing precision causes issues on mobile.
3. Not Handling Pixel Density
On retina screens, texture coordinates may be half-pixel offset. Pass screen size as uniform.
4. Shader Compilation Errors Silent
Listen to WebGL errors. Use scene.debugLayer.show() to inspect shader errors.
5. Too Many Branching Operations
Dynamic branches in shaders hurt performance on mobile GPUs. Use step() and mix() instead.
Practice Questions
Q1: What is ShaderMaterial? A: A material that uses custom GLSL vertex and fragment shaders instead of the built-in pipeline.
Q2: How do you pass time to a shader? A: Add 'time' to uniforms and set it each frame: mat.setFloat('time', performance.now() / 1000).
Q3: Where are shader files stored? A: In Babylon.js's Effect.ShadersStore or as separate .glsl files loaded via the assets manager.
Q4: What is a post-process shader? A: A shader that processes the rendered frame as a full-screen quad for effects like blur, bloom, color grading.
Q5: How do you debug shader errors? A: Check console for WebGL warnings. Use scene.debugLayer to inspect shader compilation.
Challenge: Build a vertex displacement shader that makes a sphere wobble like a water balloon. Use time uniform and vertex position manipulation.
FAQ
Try It Yourself
Build an inline color-changing shader.
<!DOCTYPE html>
<html>
<head>
<title>Babylon.js Shaders</title>
<script src="https://cdn.babylonjs.com/babylon.js"></script>
</head>
<body style="font-family:sans-serif;padding:20px;">
<h2>Custom Shader</h2>
<canvas id="renderCanvas" style="width:100%;height:400px;border-radius:8px;"></canvas>
<script>
var canvas = document.getElementById('renderCanvas');
var engine = new BABYLON.Engine(canvas, true);
var scene = new BABYLON.Scene(engine);
var camera = new BABYLON.ArcRotateCamera('camera', -Math.PI/2, Math.PI/3, 5, BABYLON.Vector3.Zero(), scene);
camera.attachControl(canvas, true);
new BABYLON.HemisphericLight('light', new BABYLON.Vector3(0, 1, 0), scene);
BABYLON.Effect.ShadersStore['pulseVertexShader'] = 'precision highp float; attribute vec3 position; uniform mat4 worldViewProjection; varying vec3 vPosition; void main() { vPosition = position; gl_Position = worldViewProjection * vec4(position, 1.0); }';
BABYLON.Effect.ShadersStore['pulseFragmentShader'] = 'precision highp float; uniform float time; varying vec3 vPosition; void main() { vec3 color = vec3(abs(sin(length(vPosition) * 3.0 - time * 2.0)), 0.2, 0.5); gl_FragColor = vec4(color, 1.0); }';
var shaderMat = new BABYLON.ShaderMaterial('pulse', scene, {
vertex: 'pulseVertex',
fragment: 'pulseFragment',
attributes: ['position'],
uniforms: ['worldViewProjection', 'time']
});
var sphere = BABYLON.MeshBuilder.CreateSphere('sphere', { diameter: 2 }, scene);
sphere.material = shaderMat;
scene.registerBeforeRender(function() {
shaderMat.setFloat('time', performance.now() / 1000);
});
engine.runRenderLoop(function() { scene.render(); });
window.addEventListener('resize', function() { engine.resize(); });
</script>
</body>
</html>
What's Next
Add post-processing effects.
Post Process — Post-processing effects. Sprites Particles — Sprites and particles.
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