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169 lines
5.4 KiB
169 lines
5.4 KiB
<!DOCTYPE html>
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<html lang="zh">
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<head>
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<meta charset="utf-8" />
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<base href="../../../" />
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<script src="page.js"></script>
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<link type="text/css" rel="stylesheet" href="page.css" />
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</head>
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<body>
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[page:Object3D] → [page:Light] →
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<h1>聚光灯（[name]）</h1>
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<p class="desc">
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光线从一个点沿一个方向射出，随着光线照射的变远，光线圆锥体的尺寸也逐渐增大。<br /><br />
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该光源可以投射阴影 - 跳转至 [page:SpotLightShadow] 查看更多细节。
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</p>
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<h2>代码示例</h2>
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<code>
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// white spotlight shining from the side, modulated by a texture, casting a shadow
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const spotLight = new THREE.SpotLight( 0xffffff );
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spotLight.position.set( 100, 1000, 100 );
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spotLight.map = new THREE.TextureLoader().load( url );
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spotLight.castShadow = true;
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spotLight.shadow.mapSize.width = 1024;
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spotLight.shadow.mapSize.height = 1024;
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spotLight.shadow.camera.near = 500;
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spotLight.shadow.camera.far = 4000;
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spotLight.shadow.camera.fov = 30;
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scene.add( spotLight );
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</code>
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<h2>例子</h2>
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<p>
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[example:webgl_lights_spotlight lights / spotlight ]<br />
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[example:webgl_lights_spotlights lights / spotlights ]
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</p>
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<h2>构造器（Constructor）</h2>
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<h3>[name]( [param:Integer color], [param:Float intensity], [param:Float distance], [param:Radians angle], [param:Float penumbra], [param:Float decay] )</h3>
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<p>
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[page:Integer color] - (可选参数) 十六进制光照颜色。 缺省值 0xffffff (白色)。<br />
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[page:Float intensity] - (可选参数) 光照强度。 缺省值 1。<br />
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[page:Float distance] - 从光源发出光的最大距离，其强度根据光源的距离线性衰减。 <br />
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[page:Radians angle] - 光线散射角度，最大为Math.PI/2。<br />
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[page:Float penumbra] - 聚光锥的半影衰减百分比。在0和1之间的值。默认为0。<br />
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[page:Float decay] - 沿着光照距离的衰减量。<br /><br />
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创建一个新的聚光灯。
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</p>
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<h2>属性（Properties）</h2>
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<p>公共属性请查看基类[page:Light Light]。</p>
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<h3>[property:Float angle]</h3>
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<p>
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从聚光灯的位置以弧度表示聚光灯的最大范围。应该不超过 *Math.PI/2*。默认值为 *Math.PI/3*。
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</p>
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<h3>[property:Boolean castShadow]</h3>
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<p>
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此属性设置为 *true* 聚光灯将投射阴影。警告: 这样做的代价比较高而且需要一直调整到阴影看起来正确。
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查看 [page:SpotLightShadow] 了解详细信息。
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默认值为 *false*
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</p>
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<h3>[property:Float decay]</h3>
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<p>
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The amount the light dims along the distance of the light. Default is `2`.<br />
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In context of physically-correct rendering the default value should not be changed.
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</p>
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<h3>[property:Float distance]</h3>
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<p>
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如果非零，那么光强度将会从最大值当前灯光位置处按照距离线性衰减到0。
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缺省值为 *0.0*。
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</p>
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<h3>[property:Boolean isSpotLight]</h3>
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<p>
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Read-only flag to check if a given object is of type [name].
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</p>
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<h3>[property:Float penumbra]</h3>
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<p>
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聚光锥的半影衰减百分比。在0和1之间的值。
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默认值 — 0.0。
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</p>
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<h3>[property:Vector3 position]</h3>
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<p>
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假如这个值设置等于 [page:Object3D.DefaultUp] (0, 1, 0)，那么光线将会从上往下照射。
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</p>
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<h3>[property:Float power]</h3>
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<p>
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光功率<br />
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在 [page:WebGLRenderer.physicallyCorrectLights physically correct] 模式中，
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表示以"流明（光通量单位）"为单位的光功率。 缺省值 - *4Math.PI*。 <br /><br />
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该值与 [page:.intensity intensity] 直接关联
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<code>
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power = intensity * 4π
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</code>
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修改该值也会导致光强度的改变。
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</p>
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<h3>[property:SpotLightShadow shadow]</h3>
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<p>
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[page:SpotLightShadow]用与计算此光照的阴影。
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</p>
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<h3>[property:Object3D target]</h3>
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<p>
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聚光灯的方向是从它的位置到目标位置.默认的目标位置为原点 *(0,0,0)*。<br />
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注意: 对于目标的位置，要将其更改为除缺省值之外的任何位置，它必须被添加到 [page:Scene scene]
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场景中去。
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<code>
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scene.add( light.target );
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</code>
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这使得属性target中的 [page:Object3D.matrixWorld matrixWorld] 会每帧自动更新。<br /><br />
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它也可以设置target为场景中的其他对象(任意拥有 [page:Object3D.position position] 属性的对象), 示例如下:
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<code>
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const targetObject = new THREE.Object3D();
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scene.add(targetObject);
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light.target = targetObject;
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</code>
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完成上述操作后，聚光灯现在就可以追踪到目标对像了。
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</p>
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<h3>[property:Texture map]</h3>
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<p>
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A [page:Texture] used to modulate the color of the light. The spot light color is mixed
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with the RGB value of this texture, with a ratio corresponding to its
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alpha value. The cookie-like masking effect is reproduced using pixel values (0, 0, 0, 1-cookie_value).
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*Warning*: [param:SpotLight map] is disabled if [param:SpotLight castShadow] is *false*.
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</p>
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<h2>方法（Methods）</h2>
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<p>公共方法请查看基类 [page:Light Light]。</p>
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<h3>[method:this copy]( [param:SpotLight source] )</h3>
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<p>
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将所有属性的值从源 [page:SpotLight source] 复制到此聚光灯光源对象。
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</p>
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<p>
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[link:https://github.com/mrdoob/three.js/blob/master/src/[path].js src/[path].js]
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</p>
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</body>
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</html>
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