Loading grass image in cloth animation three.js example is slower than Firefox

[jdm]

https://threejs.org/examples/webgl_animation_cloth.html

It relies on https://github.com/mrdoob/three.js/blob/dev/src/extras/ImageUtils.js, so it would be worth checking how long that operation takes.

[nox]

Those canvas functions are all pretty naively implemented, with a lot of useless message passing and inefficient vector operations.

[nox]

Locally I see that the animation itself is slow, but I don't see it being slower to load.

[nox]

Btw this demo complains about a missing extension:

THREE.WebGLRenderer: WEBGL_depth_texture extension not supported.

[nox]

Loading the image on Android doesn't seem slow to load, but then if you refresh the page it doesn't load again ever. Did you ever see something like that @jdm?

[jdm]

I have seen that, yes. Are you comparing the loading speed against Firefox?

[nox]

So I think the slow function is uploadTexture, but I literally can't measure anything because console.log output doesn't really show up in adb logcat. I'm out of ideas on how to debug Servo on Android. I double checked that the function in which I wrote console.log is actually executed by calling baguette() and then checking that "baguette is not defined" is shown in the output of adb logcat.

[nox]

I suspect the slow thing is https://github.com/mrdoob/three.js/blob/feb480aaffe97d6dea51a0872c2e3c58f329a026/src/renderers/webgl/WebGLTextures.js#L678

[nox]

This function call ends up calling WebGLRenderingContext::prepare_pixels, which wouldn't surprise me if it is slow, given it fetches a 2048x2048 picture and premultiplies it etc.

[nox]

This takes ~100ms to execute as I imagined it would.