<div>
  feDiffuseLighting.lighting-color = 
  <input id="lightingColor" type="color"value="#ffffff" oninput="onColorChange(arguments[0])" />
</div>
<div>
  feDiffuseLighting.surfaceScale = 
  <input id="surfaceScale" type="number" step="1" value="1" oninput="onSurfaceScaleChange(arguments[0])" />
</div>
<div>
  feDiffuseLighting.diffuseConstant = 
  <input id="diffuseConstant" type="number" step="0.1" value="1" min="0" oninput="onDiffuseConstantChange(arguments[0])" />
</div>
<br>
<div>
  feSpotLight.z = 
  <input id="feSpotLightZ" type="number" step="1" value="10" oninput="onZChange(arguments[0])" />
</div>
<div>
  feSpotLight.pointsAtX = 
  <input id="pointsAtX" type="number" step="5" value="100" oninput="onPointsXChange(arguments[0])" />
</div>
<div>
  feSpotLight.pointsAtY = 
  <input id="pointsAtY" type="number" step="5" value="120" oninput="onPointsYChange(arguments[0])" />
</div>
<div>
  feSpotLight.pointsAtZ = 
  <input id="pointsAtZ" type="number" step="5" value="0" oninput="onPointsZChange(arguments[0])" />
</div>
<div>
  feSpotLight.specularExponent = 
  <input id="specularExponent" type="number" step="5" value="1" oninput="onSpecularExponentChange(arguments[0])" />
</div>
<div>
  feSpotLight.limitingConeAngle = 
  <input id="limitingConeAngle" type="number" step="5" value="45" oninput="onLimitingConeAngleChange(arguments[0])" />
</div>
<br>

<svg width="400" height="200" xmlns="http://www.w3.org/2000/svg" onmousemove="onMouseMove(arguments[0])">

  <!-- No light is applied -->
  <text text-anchor="middle" x="100" y="20">No Light</text>
  <circle id="myCircle" cx="100" cy="120" r="50" fill="green" />
  
  <filter id="filterLight">
    <feDiffuseLighting id="feDiffuseLighting" lighting-color="white" surfaceScale="1">
      <feSpotLight id="feSpotLight" x="100" y="120" z="10" pointsAtX="100" pointsAtY="120" pointsAtZ="0" specarExponent="1" limitingConeAngle="45" />
    </feDiffuseLighting>
  </filter>
  <g transform="translate(200)">
    <text text-anchor="middle" x="100" y="20">feSpotLight 聚光灯</text>
    <use href="#myCircle" filter="url(#filterLight)" />
  </g>
  <circle id="myPoint" cx="300" cy="120" r="5" fill="red" />
  <line id="myLine" x1="300" y1="120" x2="300" y2="120" stroke="red" />
  <circle id="myPointAt" cx="300" cy="120" r="5" fill="blue" />
</svg>

function onColorChange(e) {
  const feDiffuseLighting = document.getElementById("feDiffuseLighting");
  feDiffuseLighting.setAttribute("lighting-color", e.target.value);
}
function onSurfaceScaleChange(e) {
  const feDiffuseLighting = document.getElementById("feDiffuseLighting");
  feDiffuseLighting.setAttribute("surfaceScale", e.target.value);
}
function onDiffuseConstantChange(e) {
  const feDiffuseLighting = document.getElementById("feDiffuseLighting");
  feDiffuseLighting.setAttribute("diffuseConstant", e.target.value);
}
function onZChange(e) {
  const feSpotLight = document.getElementById("feSpotLight");
  feSpotLight.setAttribute("z", e.target.value);
}
function onPointsXChange(e) {
  const feSpotLight = document.getElementById("feSpotLight");
  feSpotLight.setAttribute("pointsAtX", e.target.value);
  
  const x = +e.target.value + 200
  const myLine = document.getElementById("myLine");
  myLine.setAttribute("x2", x);
  const myPointAt = document.getElementById("myPointAt");
  myPointAt.setAttribute("cx", x);
}
function onPointsYChange(e) {
  const feSpotLight = document.getElementById("feSpotLight");
  feSpotLight.setAttribute("pointsAtY", e.target.value);
  
  const myLine = document.getElementById("myLine");
  myLine.setAttribute("y2", e.target.value);
  const myPointAt = document.getElementById("myPointAt");
  myPointAt.setAttribute("cy", e.target.value);
}
function onPointsZChange(e) {
  const feSpotLight = document.getElementById("feSpotLight");
  feSpotLight.setAttribute("pointsAtZ", e.target.value);
}
function onSpecularExponentChange(e) {
  const feSpotLight = document.getElementById("feSpotLight");
  feSpotLight.setAttribute("specularExponent", e.target.value);
}
function onLimitingConeAngleChange(e) {
  const feSpotLight = document.getElementById("feSpotLight");
  feSpotLight.setAttribute("limitingConeAngle", e.target.value);
}
function onMouseMove(e) {
  console.log(e)
  const myPoint = document.getElementById("myPoint");
  myPoint.setAttribute("cx", e.offsetX);
  myPoint.setAttribute("cy", e.offsetY);
  const myLine = document.getElementById("myLine");
  myLine.setAttribute("x1", e.offsetX);
  myLine.setAttribute("y1", e.offsetY);

  const feSpotLight = document.getElementById("feSpotLight");
  // 因为 g.transform="translate(200)"，所以这里需要减去 200
  feSpotLight.setAttribute("x", e.offsetX - 200);
  feSpotLight.setAttribute("y", e.offsetY);
}