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143 lines
4.6 KiB
143 lines
4.6 KiB
3 years ago
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<!DOCTYPE html>
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<html lang="en">
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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>[name]</h1>
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<p class="desc">
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A light that gets emitted in a specific direction. This light will behave as though it is
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infinitely far away and the rays produced from it are all parallel. The common use case
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for this is to simulate daylight; the sun is far enough away that its position can be
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considered to be infinite, and all light rays coming from it are parallel.<br /><br />
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This light can cast shadows - see the [page:DirectionalLightShadow] page for details.
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</p>
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<h2>A Note about Position, Target and rotation</h2>
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<p>
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A common point of confusion for directional lights is that setting the rotation has no effect.
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This is because three.js's DirectionalLight is the equivalent to what is often called a 'Target
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Direct Light' in other applications.<br /><br />
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This means that its direction is calculated as pointing
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from the light's [page:Object3D.position position] to the [page:.target target]'s position
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(as opposed to a 'Free Direct Light' that just has a rotation component).<br /><br />
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The reason for this is to allow the light to cast shadows - the [page:.shadow shadow]
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camera needs a position to calculate shadows from.<br /><br />
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See the [page:.target target] property below for details on updating the target.
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</p>
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<h2>Code Example</h2>
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<code>
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// White directional light at half intensity shining from the top.
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const directionalLight = new THREE.DirectionalLight( 0xffffff, 0.5 );
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scene.add( directionalLight );
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</code>
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<h2>Examples</h2>
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<p>
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[example:misc_controls_fly controls / fly ]<br />
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[example:webgl_effects_parallaxbarrier effects / parallaxbarrier ]<br />
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[example:webgl_effects_stereo effects / stereo ]<br />
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[example:webgl_geometry_extrude_splines geometry / extrude / splines ]<br />
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[example:webgl_materials_bumpmap materials / bumpmap ]
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</p>
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<h2>Constructor</h2>
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<h3>[name]( [param:Integer color], [param:Float intensity] )</h3>
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<p>
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[page:Integer color] - (optional) hexadecimal color of the light. Default is 0xffffff (white).<br />
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[page:Float intensity] - (optional) numeric value of the light's strength/intensity. Default is 1.<br /><br />
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Creates a new [name].
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</p>
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<h2>Properties</h2>
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<p>See the base [page:Light Light] class for common properties.</p>
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<h3>[property:Boolean castShadow]</h3>
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<p>
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If set to `true` light will cast dynamic shadows. *Warning*: This is expensive and
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requires tweaking to get shadows looking right. See the [page:DirectionalLightShadow] for details.
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The default is `false`.
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</p>
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<h3>[property:Boolean isDirectionalLight]</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:Vector3 position]</h3>
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<p>
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This is set equal to [page:Object3D.DefaultUp] (0, 1, 0), so that the light shines from the top down.
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</p>
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<h3>[property:DirectionalLightShadow shadow]</h3>
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<p>
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A [page:DirectionalLightShadow] used to calculate shadows for this light.
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</p>
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<h3>[property:Object3D target]</h3>
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<p>
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The DirectionalLight points from its [page:.position position] to target.position. The default
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position of the target is `(0, 0, 0)`.<br />
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*Note*: For the target's position to be changed to anything other than the default,
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it must be added to the [page:Scene scene] using
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</p>
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<code>
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scene.add( light.target );
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</code>
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<p>
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This is so that the target's [page:Object3D.matrixWorld matrixWorld] gets automatically
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updated each frame.<br /><br />
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It is also possible to set the target to be another object in the scene (anything with a
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[page:Object3D.position position] property), like so:
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</p>
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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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<p>
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The directionalLight will now track the target object.
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</p>
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<h2>Methods</h2>
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<p>See the base [page:Light Light] class for common methods.</p>
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<h3>[method:undefined dispose]()</h3>
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<p>
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Frees the GPU-related resources allocated by this instance. Call this method whenever this instance is no longer used in your app.
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</p>
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<h3>[method:this copy]( [param:DirectionalLight source] )</h3>
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<p>
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Copies value of all the properties from the [page:DirectionalLight source] to this
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DirectionalLight.
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</p>
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<h2>Source</h2>
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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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