<svg width="440" height="140" xmlns="http://www.w3.org/2000/svg">

  <!-- No light is applied -->
  <text text-anchor="middle" x="60" y="22">原图</text>
  <circle cx="60" cy="80" r="50" fill="green" />

  <!-- the light source is a fePointLight element -->
  <text text-anchor="middle" x="170" y="22">点状光</text>
  <filter id="lightMe1">
    <feDiffuseLighting in="SourceGraphic" result="light" lighting-color="white">
      <fePointLight x="150" y="60" z="20" />
    </feDiffuseLighting>

    <feComposite in="SourceGraphic" in2="light"
                 operator="arithmetic" k1="1" k2="0" k3="0" k4="0"/>
  </filter>

  <circle cx="170" cy="80" r="50" fill="green" filter="url(#lightMe1)" />

  <!-- the light source is a feDistantLight element -->
  <text text-anchor="middle" x="280" y="22">平行光</text>
  <filter id="lightMe2">
    <feDiffuseLighting in="SourceGraphic" result="light" lighting-color="white">
      <feDistantLight azimuth="240" elevation="20"/>
    </feDiffuseLighting>

    <feComposite in="SourceGraphic" in2="light"
                 operator="arithmetic" k1="1" k2="0" k3="0" k4="0"/>
  </filter>

  <circle cx="280" cy="80" r="50" fill="green" filter="url(#lightMe2)" />

  <!-- the light source is a feSpotLight source -->
  <text text-anchor="middle" x="390" y="22">聚光</text>
  <filter id="lightMe3">
    <feDiffuseLighting in="SourceGraphic" result="light" lighting-color="white">
      <feSpotLight x="360" y="5" z="30" limitingConeAngle="20"
                   pointsAtX="390" pointsAtY="80" pointsAtZ="0"/>
    </feDiffuseLighting>

    <feComposite in="SourceGraphic" in2="light"
                 operator="arithmetic" k1="1" k2="0" k3="0" k4="0"/>
  </filter>

  <circle cx="390" cy="80" r="50" fill="green" filter="url(#lightMe3)" />
</svg>