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// =====================================
// write your own fragment shader below
// =====================================
fragShaderSource = `
precision highp float; // 声明float的精度
#define PI 3.14159265359
// JS与shader单向通信的变量
uniform vec2 u_size; // 当前画布的尺寸
// 2D Random
float random (in vec2 st) {
return fract(sin(dot(st.xy,
vec2(12.9898,78.233)))
* 43758.5453123);
}
// 2D Noise based on Morgan McGuire @morgan3d
// https://www.shadertoy.com/view/4dS3Wd
float noise (in vec2 st) {
vec2 i = floor(st);
vec2 f = fract(st);
// Four corners in 2D of a tile
float a = random(i);
float b = random(i + vec2(1.0, 0.0));
float c = random(i + vec2(0.0, 1.0));
float d = random(i + vec2(1.0, 1.0));
// Smooth Interpolation
// Cubic Hermine Curve. Same as SmoothStep()
vec2 u = f*f*(3.0-2.0*f);
// u = smoothstep(0.,1.,f);
// Mix 4 coorners percentages
return mix(a, b, u.x) +
(c - a)* u.y * (1.0 - u.x) +
(d - b) * u.x * u.y;
}
void main() {
vec2 st = gl_FragCoord.xy/u_size.xy;
// Scale the coordinate system to see
// some noise in action
vec2 pos = vec2(st*float(${factor}));
// Use the noise function
float n = noise(pos);
gl_FragColor = vec4(vec3(n), 1.0);
}
`
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
