Rendering artifacts with sdf icons

[LukasPaczos]

Refs mapbox/mapbox-plugins-android#971.

Whenever an SDF icon is laid out on the same tile (group of tiles?) as a non-SDF icon, the non-SDF becomes SDF as well and changes its color to the color of the SDF and has troubles rendering which can be seen in mapbox/mapbox-plugins-android#971 (lags when animating).

The reproducible case below - https://github.com/mapbox/mapbox-gl-native/tree/lp-sdf-artifacts-repro

Above uses maki, but also reproducible when explicitly adding a non-sdf icon:

Feature feature1 = Feature.fromGeometry(Point.fromLngLat(16, 50));
feature1.addStringProperty("icon", "non-sdf-image");

Feature feature2 = Feature.fromGeometry(Point.fromLngLat(-15, 40));
feature2.addStringProperty("icon", "sdf-image");

Bitmap bitmap = BitmapUtils.getBitmapFromDrawable(ContextCompat.getDrawable(SimpleMapActivity.this,
  R.drawable.mapbox_user_puck_icon));
if (bitmap != null) {
  style.addImage("sdf-image", bitmap, true /*SDF*/);
}

Bitmap bitmap1 = BitmapUtils.getBitmapFromDrawable(ContextCompat.getDrawable(SimpleMapActivity.this,
  R.drawable.mapbox_user_puck_icon));
if (bitmap1 != null) {
  style.addImage("non-sdf-image", bitmap1, false /*NON-SDF*/);
}

[LukasPaczos]

I went as far back as 7.1.0 and the issue was still reproducible.

/cc @tmpsantos

[LukasPaczos]

has troubles rendering which can be seen in mapbox/mapbox-plugins-android#971 (lags when animating)

Reopening because even though the icons are not treated as SDFs visually, the rendering performance is still impacted. See mapbox/mapbox-plugins-android#971 (comment).

If the layer contains only SDF icons or only non-SDF icons the performance is fine, we're running into the issue again only when there's a mix of SDF and non-SDF icons on the same layer.

[alexshalamov]

@LukasPaczos should we split this issue into two? Issue with mixing sdf and non-sdf icons and applying color is one issue. Performance lag is another issue that should be investigated separately.

@zmiao what do you think?

[zmiao]

I agree with @alexshalamov, the lagging issue could be handled separately, is it fine for you @LukasPaczos ?

[LukasPaczos]

Sure, let me cut a new ticket 👍

[LukasPaczos]

Continuing in #15509.