Generating a PMREM texture offline?

Questions
1

I currently create a PMREM environment map from a cubemap at runtime with the following code but it crashes on iPhone:

const pmremGenerator = new THREE.PMREMGenerator(renderer);
pmremGenerator.compileCubemapShader();
const cubeTextureLoader = new THREE.CubeTextureLoader();
cubeTextureLoader.load([
  '/assets/env-sky-cube-posx.jpg',
  '/assets/env-sky-cube-negx.jpg',
  '/assets/env-sky-cube-posy.jpg',
  '/assets/env-sky-cube-negy.jpg',
  '/assets/env-sky-cube-posz.jpg',
  '/assets/env-sky-cube-negz.jpg',
], texture => {
  const environmentMap = pmremGenerator.fromCubemap(texture).texture;
  texture.dispose();
  pmremGenerator.dispose();
  scene.environment = environmentMap;
  scene.background = environmentMap;
});

In Babylon.js I can create a .env file offline using CubeMapGen and .DDS to .ENV utility and load it with:

const environmentTexture = BABYLON.CubeTexture.CreateFromPrefilteredData('/assets/env-sky-cube.env', scene);
scene.createDefaultSkybox(environmentTexture);

Is there a way to do something similar in Three.js? Can PMREMGenerator save to a .env or .dds file?

2

It’s possible to export the PMREM texture to a .exr file as shown in the EXRExporter example. Or alternatively, a .ktx2 file after this PR.

I’m not really familiar with .env files, and three.js does not provide a .dds exporter, but it is of course also possible to write the PMREM texture to a DataTexture and then do something directly with the typed array of pixel values.

3

Thanks for the link to the example. Looking at the image generated it seems to allocate very few pixels to incrementally blurring the image (16x16 pixels).

4

The blur used in the PMREM textures is optimized for use in lighting of rough surfaces, and not for high-res display as the background of the scene. For that purpose you might want to use scene.backgroundBlurriness, though I’m not sure how/if that can be exported.