function calculateLights( lights ) {

			_ambientLight.setRGB( 0, 0, 0 );
			_directionalLights.setRGB( 0, 0, 0 );
			_pointLights.setRGB( 0, 0, 0 );

			for ( let l = 0, ll = lights.length; l < ll; l ++ ) {

				const light = lights[ l ];
				const lightColor = light.color;

				if ( light.isAmbientLight ) {

					_ambientLight.r += lightColor.r;
					_ambientLight.g += lightColor.g;
					_ambientLight.b += lightColor.b;

				} else if ( light.isDirectionalLight ) {

					_directionalLights.r += lightColor.r;
					_directionalLights.g += lightColor.g;
					_directionalLights.b += lightColor.b;

				} else if ( light.isPointLight ) {

					_pointLights.r += lightColor.r;
					_pointLights.g += lightColor.g;
					_pointLights.b += lightColor.b;

				}

			}

		}
Renders the given scene using the given camera.

@param {Object3D} scene - A scene or any other type of 3D object.
@param {Camera} camera - The camera.