Code and stories for ABC News and other experiments online
Public
Edited
Jan 24, 2022
1 fork
5 stars
{
const frame = regl.frame(function(context) {
regl.clear({
color: [0.0, 0.0, 0.0, 1],
depth: 1
});
// Each loop, update the data
updateData(points);
// And draw it!
drawDots({
pointWidth: 1,
points: points
});
});
invalidation.then(() => frame.cancel());
}
drawDots = regl({
frag: `
precision mediump float;
uniform vec4 color;
void main () {
float r = 0.0, delta = 0.0, alpha = 1.0;
vec2 cxy = 2.0 * gl_PointCoord - 1.0;
r = dot(cxy, cxy);
if (r > 1.0) {
discard;
}
gl_FragColor = color * alpha;
}`,
vert: `
precision mediump float;
attribute vec2 position;
attribute float pointWidth;
uniform float stageWidth;
uniform float stageHeight;
// helper function to transform from pixel space to normalized
// device coordinates (NDC). In NDC (0,0) is the middle,
// (-1, 1) is the top left and (1, -1) is the bottom right.
// Stolen from Peter Beshai's great blog post:
// http://peterbeshai.com/beautifully-animate-points-with-webgl-and-regl.html
vec2 normalizeCoords(vec2 position) {
// read in the positions into x and y vars
float x = position[0];
float y = position[1];
return vec2(
2.0 * ((x / stageWidth) - 0.5),
// invert y to treat [0,0] as bottom left in pixel space
-(2.0 * ((y / stageHeight) - 0.5)));
}
void main () {
gl_PointSize = pointWidth;
gl_Position = vec4(normalizeCoords(position), 0, 1);
}`,
attributes: {
position: function(context, props) {
return props.points.map(function(point) {
return [point.x, point.y];
});
},
pointWidth: function(context, props) {
return props.points.map(function(point) {
return point.size;
});
}
},
uniforms: {
color: function(context, props) {
// just to be a bit strange, oscillate the color a bit.
return [Math.cos(context.tick / 100), 0.704, 1.0, 1.0];
},
stageWidth: regl.context("drawingBufferWidth"),
stageHeight: regl.context("drawingBufferHeight")
},
count: function(context, props) {
// set the count based on the number of points we have
return props.points.length;
},
primitive: "points"
});
updateData = (data) => {
data.forEach(function(datum) {
datum.x += datum.speed;
// reset x if its gone past max width
datum.x = datum.x > width ? 0 : datum.x;
});
}
points = createData(numberOfStars);
createData = (dataCount) => {
restart;
var data = [];
for (var i = 0; i < dataCount; i++) {
var datum = {
id: i,
speed: randomFromInterval(1, 1.2),
y: randomIntFromInterval(1, width / 1.6),
x: randomIntFromInterval(1, width),
size: randomIntFromInterval(1.5, 3.1)
};
data.push(datum);
}
return data;
}
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