引擎加载 初始化

class Sence {

   constructor( geometry, options = {} ) {

      super( geometry );

      this.isReflector = true;

      this.type = 'Reflector';
      this.camera = new PerspectiveCamera();

      const scope = this;

      const color = ( options.color !== undefined ) ? new Color( options.color ) : new Color( 0x7F7F7F );
      const textureWidth = options.textureWidth || 512;
      const textureHeight = options.textureHeight || 512;
      const clipBias = options.clipBias || 0;
      const shader = options.shader || Reflector.ReflectorShader;
      const multisample = ( options.multisample !== undefined ) ? options.multisample : 4;

      //

      const reflectorPlane = new Plane();
      const normal = new Vector3();
      const reflectorWorldPosition = new Vector3();
      const cameraWorldPosition = new Vector3();
      const rotationMatrix = new Matrix4();
      const lookAtPosition = new Vector3( 0, 0, - 1 );
      const clipPlane = new Vector4();

      const view = new Vector3();
      const target = new Vector3();
      const q = new Vector4();

      const textureMatrix = new Matrix4();
      const virtualCamera = this.camera;

      const renderTarget = new WebGLRenderTarget( textureWidth, textureHeight, { samples: multisample, type: HalfFloatType } );

      const material = new ShaderMaterial( {
         name: ( shader.name !== undefined ) ? shader.name : 'unspecified',
         uniforms: UniformsUtils.clone( shader.uniforms ),
         fragmentShader: shader.fragmentShader,
         vertexShader: shader.vertexShader
      } );

      material.uniforms[ 'tDiffuse' ].value = renderTarget.texture;
      material.uniforms[ 'color' ].value = color;
      material.uniforms[ 'textureMatrix' ].value = textureMatrix;

      this.material = material;

      this.onBeforeRender = function ( renderer, scene, camera ) {

         reflectorWorldPosition.setFromMatrixPosition( scope.matrixWorld );
         cameraWorldPosition.setFromMatrixPosition( camera.matrixWorld );

         rotationMatrix.extractRotation( scope.matrixWorld );

         normal.set( 0, 0, 1 );
         normal.applyMatrix4( rotationMatrix );

         view.subVectors( reflectorWorldPosition, cameraWorldPosition );

         // Avoid rendering when reflector is facing away

         if ( view.dot( normal ) > 0 ) return;

         view.reflect( normal ).negate();
         view.add( reflectorWorldPosition );

         rotationMatrix.extractRotation( camera.matrixWorld );

         lookAtPosition.set( 0, 0, - 1 );
         lookAtPosition.applyMatrix4( rotationMatrix );
         lookAtPosition.add( cameraWorldPosition );

         target.subVectors( reflectorWorldPosition, lookAtPosition );
         target.reflect( normal ).negate();
         target.add( reflectorWorldPosition );

         virtualCamera.position.copy( view );
         virtualCamera.up.set( 0, 1, 0 );
         virtualCamera.up.applyMatrix4( rotationMatrix );
         virtualCamera.up.reflect( normal );
         virtualCamera.lookAt( target );

         virtualCamera.far = camera.far; // Used in WebGLBackground

         virtualCamera.updateMatrixWorld();
         virtualCamera.projectionMatrix.copy( camera.projectionMatrix );

         // Update the texture matrix
         textureMatrix.set(
            0.5, 0.0, 0.0, 0.5,
            0.0, 0.5, 0.0, 0.5,
            0.0, 0.0, 0.5, 0.5,
            0.0, 0.0, 0.0, 1.0
         );
         textureMatrix.multiply( virtualCamera.projectionMatrix );
         textureMatrix.multiply( virtualCamera.matrixWorldInverse );
         textureMatrix.multiply( scope.matrixWorld );

         // Now update projection matrix with new clip plane, implementing code from: http://www.terathon.com/code/oblique.html
         // Paper explaining this technique: http://www.terathon.com/lengyel/Lengyel-Oblique.pdf
         reflectorPlane.setFromNormalAndCoplanarPoint( normal, reflectorWorldPosition );
         reflectorPlane.applyMatrix4( virtualCamera.matrixWorldInverse );

         clipPlane.set( reflectorPlane.normal.x, reflectorPlane.normal.y, reflectorPlane.normal.z, reflectorPlane.constant );

         const projectionMatrix = virtualCamera.projectionMatrix;

         q.x = ( Math.sign( clipPlane.x ) + projectionMatrix.elements[ 8 ] ) / projectionMatrix.elements[ 0 ];
         q.y = ( Math.sign( clipPlane.y ) + projectionMatrix.elements[ 9 ] ) / projectionMatrix.elements[ 5 ];
         q.z = - 1.0;
         q.w = ( 1.0 + projectionMatrix.elements[ 10 ] ) / projectionMatrix.elements[ 14 ];

         // Calculate the scaled plane vector
         clipPlane.multiplyScalar( 2.0 / clipPlane.dot( q ) );

         // Replacing the third row of the projection matrix
         projectionMatrix.elements[ 2 ] = clipPlane.x;
         projectionMatrix.elements[ 6 ] = clipPlane.y;
         projectionMatrix.elements[ 10 ] = clipPlane.z + 1.0 - clipBias;
         projectionMatrix.elements[ 14 ] = clipPlane.w;

         // Render
         scope.visible = false;

         const currentRenderTarget = renderer.getRenderTarget();

         const currentXrEnabled = renderer.xr.enabled;
         const currentShadowAutoUpdate = renderer.shadowMap.autoUpdate;

         renderer.xr.enabled = false; // Avoid camera modification
         renderer.shadowMap.autoUpdate = false; // Avoid re-computing shadows

         renderer.setRenderTarget( renderTarget );

         renderer.state.buffers.depth.setMask( true ); // make sure the depth buffer is writable so it can be properly cleared, see #18897

         if ( renderer.autoClear === false ) renderer.clear();
         renderer.render( scene, virtualCamera );

         renderer.xr.enabled = currentXrEnabled;
         renderer.shadowMap.autoUpdate = currentShadowAutoUpdate;

         renderer.setRenderTarget( currentRenderTarget );

         // Restore viewport

         const viewport = camera.viewport;

         if ( viewport !== undefined ) {

            renderer.state.viewport( viewport );

         }

         scope.visible = true;

      };

      this.getRenderTarget = function () {

         return renderTarget;

      };

      this.dispose = function () {

         renderTarget.dispose();
         scope.material.dispose();

      };

   }

}