Add rendering layer for chunk section edges.

Reveals that far too many chunk sections are being created.
Edges have odd diagonals but I'll leave it for now.

src/mcedit2/rendering/chunkmeshes/chunksections.py

@@ -0,0 +1,37 @@
+"""
+    ${NAME}
+"""
+from __future__ import absolute_import, division, print_function, unicode_literals
+import logging
+from OpenGL import GL
+import numpy
+from mcedit2.rendering import renderstates, scenegraph
+from mcedit2.rendering.blockmeshes import standardCubeTemplates
+from mcedit2.rendering.blockmeshes import ChunkMeshBase
+from mcedit2.rendering.layers import Layer
+from mcedit2.rendering.slices import _XYZ, _RGBA
+from mcedit2.rendering.vertexarraybuffer import VertexArrayBuffer
+
+log = logging.getLogger(__name__)
+
+class ChunkSectionsRenderer(ChunkMeshBase):
+    layer = Layer.ChunkSections
+    renderstate = renderstates.RenderstateEntityNode
+    color = (255, 200, 255)
+
+    vertexTemplate = numpy.zeros((6, 4, 4), 'float32')
+    vertexTemplate[_XYZ] = standardCubeTemplates[_XYZ]
+    vertexTemplate[_XYZ] *= (16, 16, 16)
+    vertexTemplate.view('uint8')[_RGBA] = color + (72,)
+
+    def makeChunkVertices(self, chunk, _limitBox):
+        positions = chunk.sectionPositions()
+
+        buffer = VertexArrayBuffer((len(positions), 6, 4), GL.GL_LINE_STRIP, textures=False, lights=False)
+        for i, cy in enumerate(positions):
+            buffer.buffer[i, :] = self.vertexTemplate
+            buffer.vertex[i, ..., 1] += cy * 16
+
+        self.sceneNode = scenegraph.VertexNode(buffer)
+
+        yield

src/mcedit2/rendering/chunkupdate.py

@@ -8,6 +8,7 @@ import numpy
 from mcedit2.rendering.modelmesh import BlockModelMesh
 
 from mcedit2.rendering import layers
+from mcedit2.rendering.chunkmeshes.chunksections import ChunkSectionsRenderer
 from mcedit2.rendering.chunkmeshes.entitymesh import TileEntityMesh, MonsterRenderer, ItemRenderer
 from mcedit2.rendering.chunkmeshes.lowdetail import LowDetailBlockMesh, OverheadBlockMesh
 from mcedit2.rendering.chunkmeshes.terrainpop import TerrainPopulatedRenderer
@@ -125,6 +126,7 @@ class ChunkUpdate(object):
         ItemRenderer,
         TileTicksRenderer,
         TerrainPopulatedRenderer,
+        ChunkSectionsRenderer,
         LowDetailBlockMesh,
         OverheadBlockMesh,
     ]

src/mcedit2/rendering/layers.py

@@ -13,4 +13,5 @@ class Layer:
     TileEntities = "TileEntities"
     TileTicks = "TileTicks"
     TerrainPopulated = "TerrainPopulated"
-    AllLayers = (Blocks, Entities, Items, TileEntities, TileTicks)
+    ChunkSections = "ChunkSections"
+    AllLayers = (Blocks, Entities, Items, TileEntities, TileTicks, ChunkSections)