shader-canvas

var shaderCanvas = new ShaderCanvas();
document.body.appendChild(shaderCanvas.domElement);

shaderCanvas.setShader(`
  void main() {
    vec2 uv = gl_FragCoord.xy / iResolution.xy;
    gl_FragColor = vec4(uv.x, 0.0, uv.y, 1.0);
  }
`);

shaderCanvas.setSize(400, 400);

Shaders can be loaded from a URL:

shaderCanvas.loadShader("shader.glsl");
shaderCanvas.loadShader("//raw.githubusercontent.com/fordhurley/atom-glsl-preview/2c9d19fc/examples/frag.glsl")

It can be attached to an existing canvas:

var shaderCanvas = new ShaderCanvas({
  domElement: document.getElementById("my-canvas"),
});

A full example can be found in example/.

Uniforms

The following default uniforms are included. No need to add these into your fragment shaders:

uniform vec2 iResolution; // size of the preview
uniform vec2 iMouse; // cursor in normalized coordinates [0, 1)
uniform float iGlobalTime; // clock in seconds

The variants u_resolution, u_mouse and u_time can also be used to match the style found in The Book of Shaders.

Textures

Textures can be loaded by defining a uniform with a comment containing the path to the file. The syntax is:

uniform sampler2D <texture_name>; // <path_to_file>

For example:

uniform sampler2D inThisDirectory; // foo.jpg
uniform sampler2D inOtherDirectory; // ../other_textures/bar.png
uniform sampler2D withAbsolutePath; // /Users/ford/textures/blah.bmp
uniform sampler2D withURL; // https://example.com/textures/blah.bmp

If you need to modify the path before attempting to load the texture, override the .buildTextureURL(filePath) method of

Handling Errors

Override the following methods to handle errors and successes.

.onShaderLoad()
.onShaderError(msg, lineNumber)
.onTextureLoad()
.onTextureError(textureURL)

By default, errors throw exceptions.

Credits

Extracted from atom-glsl-preview.