Before C++11, std::list's implementation of size was O(n). It should be
all O(1) now, but it is probably still a good idea to use empty() to
emphasize the intend.
this is required so that devices that aren't using 1x or 2x (like the iPhone 6 Plus with a pixelRatio of 3x) still show icons, albeit bilinearly scaled to the correct size in the SpriteAtlas
fixes#1398
js: 212760981493460b438f1cc117001825773fad91
https://github.com/mapbox/mapbox-gl-js/pull/1195
The sprite atlas already had two empty pixels between each each icon.
But the icon's real boundary isn't used for drawing. Drawing uses an
icon's box rounded up to the nearest multiple of four. Sometimes this
rounded boundary was directly on the edge of another icon. When the icon
was sampled with linear interpolation it's edge would get polluted with
values from the other icon.
This commit shifts all icons and glyphs by 1px so that there is padding
on all sides of the box being drawn. The quads used for drawing are
shifted in the opposite direction by 1px to compensate for this.
- previously, we reallocated the glyph atlas on every upload. Instead, we're now using glTexSubImage2D to reuse the existing buffer
- we're no longer forcing a texture upload when we remove glyphs; they won't be rendered anyway
- we're now only doing a texture upload once per frame; previously, worker threads that added glyphs mid-render could trigger a texture upload while rendering is in progress
We always need to do a full upload to adjust the image buffer size when we adjust the size of our sprite atlas. This can happen when we change the pixelRatio of the map we're rendering.
This moves all texture updates and buffer uploads to the beginning of every frame, before we issue any drawing commands. This means the GPU typically has much more time to upload the data in the background until we actually need it, and doesn't have to pause to store/load the framebuffer.
On iOS, the main thread does framebuffer operations just before it requests a rerender of the view contents. This means that GL operations on the Map thread will interfere with that and cause a crash. While most GL operations happen throughout rendering (which is synchronized with the main thread), deletion of shared_ptrs release in turn their OpenGL objects. This may happen at any time and isn't synced with rendering.
This patch changes this so instead of deleting all objects immediately, we are collecting all abandoned IDs and delete them in bulk once the main thread has given us permission to use OpenGL calls (i.e. during render()).
- OpenGL ES 2 doesn't allow NPOT textures with wrap-around
- The Sprite object reported the map's pixelRatio, even though it loaded @2x assets
- Copying icons from the sprite into the atlas now uses bilinear scaling to scale up to the actual size
