remove unnecessary/unused variables, use names like shadertoy

glsl/raymarching.js

  var vertexShaderSrc = `
attribute vec4 aPosition;
attribute vec2 aSize;
varying vec3 pos;
void main() {
  gl_Position = aPosition;
  gl_PointSize = 10.0;
  pos = aPosition.xyz;
}
`
  var fragmentShaderSrc = `
precision highp float;
uniform vec2 uSize;
uniform vec2 iResolution;
uniform vec3 iMouse;
varying vec3 pos;
const int MaximumRaySteps = 150;
const float MinimumDistance = 0.0000001;
}
void main() {
  vec2 q = gl_FragCoord.xy / uSize.xy;
  vec2 q = gl_FragCoord.xy / iResolution.xy;
  vec2 p = -1.0 + 2.0*q;
  p.x *= uSize.x / uSize.y;
  //vec2 iMouse = uSize / 2.0;
  vec2 mo = iMouse.xy/uSize.xy;
  p.x *= iResolution.x / iResolution.y;
  vec2 mo = iMouse.xy/iResolution.xy;
  float time = 15.0 + 0.0; // iGlobalTime
  gl.useProgram(program);
  
  var aPosition = gl.getAttribLocation(program, 'aPosition');
  var uSize = gl.getUniformLocation(program, 'uSize');
  var iResolution = gl.getUniformLocation(program, 'iResolution');
  var iMouse = gl.getUniformLocation(program, 'iMouse');
  var uFragColor = gl.getUniformLocation(program, 'uFragColor');
  
  gl.vertexAttrib2f(aPosition, 0.0, 0.0);
  gl.uniform2f(uSize, canvas.width, canvas.height);
  gl.uniform2f(iResolution, canvas.width, canvas.height);
  gl.uniform3f(iMouse, 0.0, 0.0, 0.0);
  gl.uniform4f(uFragColor, 1.0, 0.0, 0.0, 1.0);
  
  //gl.drawArrays(gl.POINTS, 0, 1);-
  
  // two triangles
  var positions = new Float32Array([
    -1.0, 1.0,
    -1.0, -1.0,
    w = canvas.width = window.innerWidth;
    h = canvas.height = window.innerHeight;
    gl.viewport(0, 0, w, h);
    gl.uniform2f(uSize, w, h);
    gl.uniform2f(iResolution, w, h);
    gl.clearColor(0.0, 0.0, 0.0, 1.0);
    gl.clear(gl.COLOR_BUFFER_BIT);
    render();
  msg.style = "color: red; position: absolute; right: 0; bottom: 0";
  msg.textContent = e;
  document.body.appendChild(msg);
}
}