[core] Use gl::Program to resolve some rough edges in the GL binding types

* Extract `ignore` util to separate header.
* `Segment` now tracks offset and length of indices, rather than primitives. This is more natural.
* Introduce `VertexVector` and `IndexVector` types. These types carry information about the intended draw mode (`Triangles`, `LineStrip`, etc.), and ensure that elements are always appended in a group size appropriate for that draw mode, for both indexed and unindexed rendering.
* `Program`, rather than `Drawable`, is now the unifying object for draw calls. `Program` is the best place to type check the draw call, because it is typed to carry information about the intended primitive, vertex type, attributes, and uniforms.
* Use the debug shaders for debug tile rendering, like gl-js.
* Fix the draw mode for background. It was drawing triangle strips with a triangles array. Surprised this didn’t cause issues. Now it’s type checked.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/mbgl/renderer/circle_bucket.cpp b/src/mbgl/renderer/circle_bucket.cpp
index 08f2a144a1..ba2285c4eb 100644
--- a/src/mbgl/renderer/circle_bucket.cpp
+++ b/src/mbgl/renderer/circle_bucket.cpp
@@ -46,7 +46,7 @@ void CircleBucket::addGeometry(const GeometryCollection& geometryCollection) {
 
             if (segments.empty() || segments.back().vertexLength + vertexLength > std::numeric_limits<uint16_t>::max()) {
                 // Move to a new segments because the old one can't hold the geometry.
-                segments.emplace_back(vertices.size(), triangles.size());
+                segments.emplace_back(vertices.vertexSize(), triangles.indexSize());
             }
 
             // this geometry will be of the Point type, and we'll derive
@@ -73,7 +73,7 @@ void CircleBucket::addGeometry(const GeometryCollection& geometryCollection) {
             triangles.emplace_back(index, index + 3, index + 2);
 
             segment.vertexLength += vertexLength;
-            segment.primitiveLength += 2;
+            segment.indexLength += 6;
         }
     }
 }