Visualization toolmaker. Founder @observablehq. Creator @d3. Former @nytgraphics. Pronounced BOSS-tock.
Published
Edited
Jul 21, 2019
3 forks
8 stars
viewof gl = {
const canvas = document.createElement("canvas");
canvas.width = (width + 28) * devicePixelRatio;
canvas.height = height * devicePixelRatio;
canvas.style = `
margin: 0 -14px;
width: ${width + 28}px;
height: ${height}px;
`;
canvas.value = canvas.getContext("webgl");
return canvas;
}
fragmentShader = {
const shader = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(shader, `
precision highp float;
uniform vec2 u_size;
void main() {
gl_FragColor = vec4(gl_FragCoord.xy / u_size, 0.0, 1.0);
}
`);
gl.compileShader(shader);
if (gl.getShaderParameter(shader, gl.COMPILE_STATUS)) return shader;
throw new Error(gl.getShaderInfoLog(shader));
}
vertexShader = {
const shader = gl.createShader(gl.VERTEX_SHADER);
gl.shaderSource(shader, `
attribute vec2 a_vertex;
void main(void) {
gl_Position = vec4(a_vertex, 0.0, 1.0);
}
`);
gl.compileShader(shader);
if (gl.getShaderParameter(shader, gl.COMPILE_STATUS)) return shader;
throw new Error(gl.getShaderInfoLog(shader));
}
draw = {
const a_vertex = gl.getAttribLocation(program, "a_vertex");
const u_size = gl.getUniformLocation(program, "u_size");
const buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, Float32Array.of(-1, -1, +1, -1, +1, +1, -1, +1), gl.STATIC_DRAW);
gl.useProgram(program);
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.enableVertexAttribArray(a_vertex);
gl.vertexAttribPointer(a_vertex, 2, gl.FLOAT, false, 0, 0);
gl.uniform2f(u_size, viewof gl.width, viewof gl.height);
gl.drawArrays(gl.TRIANGLE_FAN, 0, 4);
}
program = {
const program = gl.createProgram();
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
if (gl.getProgramParameter(program, gl.LINK_STATUS)) return program;
throw new Error(gl.getProgramInfoLog(program));
}
height = 600
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