渲染纹理资源（RenderTexture）

渲染纹理是一张在 GPU 上的纹理。通常我们会把它设置到相机的 目标纹理 上，使相机照射的内容通过离屏的 frambuffer 绘制到该纹理上。一般可用于制作汽车后视镜，动态阴影等功能。

使用 RenderTexture

  1. // 方法一：把 3D 相机照射的内容绘制到 UI 的精灵帧上
  2. export class CaptureToWeb extends Component {
  3.     @property(SpriteComponent)
  4.     sprite: SpriteComponent = null;
  5.     @property(CameraComponent)
  6.     camera: CameraComponent = null;
  8.     protected _renderTex: RenderTexture = null;
  10.     start () {
  11.         const spriteframe = this.sprite.spriteFrame;
  12.         const sp = new SpriteFrame();
  13.         sp.reset({
  14.             originalSize: spriteframe.getOriginalSize(),
  15.             rect: spriteframe.getRect(),
  16.             offset: spriteframe.getOffset(),
  17.             isRotate: spriteframe.isRotated(),
  18.             borderTop: spriteframe.insetTop,
  19.             borderLeft: spriteframe.insetLeft,
  20.             borderBottom: spriteframe.insetBottom,
  21.             borderRight: spriteframe.insetRight,
  22.         });
  24.         const rendetTex = this._renderTex = new RenderTexture();
  25.         rendetTex.reset({
  26.             width: 256,
  27.             height: 256,
  28.             colorFormat: RenderTexture.PixelFormat.RGBA8888,
  29.             depthStencilFormat: RenderTexture.DepthStencilFormat.DEPTH_24_STENCIL_8
  30.         });
  31.         this.camera.targetTexture = rendetTex;
  32.         sp.texture = rendetTex;
  33.         this.sprite.spriteFrame = sp;
  34.     }
  35. }
  37. // 方法二：把 3D 相机照射的内容绘制到 3D 模型上
  38. export class RenderCameraToModel extends Component {
  39.     @property(ModelComponent)
  40.     model: ModelComponent = null;
  42.     start () {
  43.         // Your initialization goes here.
  44.         const renderTex = new RenderTexture();
  45.         renderTex.reset({
  46.             width: 256,
  47.             height: 256,
  48.             colorFormat: RenderTexture.PixelFormat.RGBA8888,
  49.             depthStencilFormat: RenderTexture.DepthStencilFormat.DEPTH_24_STENCIL_8,
  50.         });
  51.         const cameraComp = this.getComponent(CameraComponent);
  52.         cameraComp.targetTexture = renderTex;
  53.         const pass = this.model.material.passes[0];
  54.         const binding = pass.getBinding('mainTexture');
  55.         pass.bindTextureView(binding, renderTex.getGFXTextureView());
  56.     }
  57. }

更多方法请参考：test-case-3d