fix buggy offline triangulation, fixes #26

README.md

@@ -97,7 +97,7 @@ Many thanks to:
 - **asmx**: http://xi6.com/projects/asmx/
 - **The Sokol Headers**: https://github.com/floooh/sokol
 - **The Chips Headers (UI)**: https://github.com/floooh/chips
-- **Tripy**: https://github.com/linuxlewis/tripy
+- **Earcut-Python**: https://github.com/joshuaskelly/earcut-python
 - **IconFontCppHeaders**: https://github.com/juliettef/IconFontCppHeaders
 - **Font Awesome 4**: https://github.com/FortAwesome/Font-Awesome/tree/fa-4
 - **visual2a03**: http://www.qmtpro.com/~nes/chipimages/visual2a03/

ext/visual6502/earcut.py

@@ -1,3 +1,4 @@
+# https://github.com/joshuaskelly/earcut-python
 import math
 
 __all__ = ['earcut', 'deviation', 'flatten']
@@ -690,4 +691,4 @@ def unflatten(data):
     for i in range(0, len(data), 3):
         result.append(tuple(data[i:i + 3]))
 
-    return result
+    return result

ext/visual6502/segdefs.py

@@ -105,17 +105,74 @@ def add_tris_to_grid(layer, triangles):
                 cell_index = layer*(GRID_NUM_CELLS*GRID_NUM_CELLS)+y*GRID_NUM_CELLS+x
                 GRID_STACK[cell_index].append(tri_index)
 
+#-------------------------------------------------------------------------------
+# Some segments consist of multiple polygons, split them accordingly, the
+# returned array consists of types (node_index, start_vertex_index, num_vertices).
+#
+# Such multi-path segments only exists on the Z80 and define polygons with holes
+# (the first path is the actual poly, and all following paths are holes)
+#
+def split_segment(seg):
+    res = []
+    i0 = seg[1]
+    i1 = i0 + seg[2]
+    i_start = i0
+    # special case, v0 == v1
+    # (this is why the original renderer moves the first vertex to the end:
+    # https://github.com/trebonian/visual6502/blob/d8ecc129b34e0eaf320e0400fcf33329475bdb1e/wires.js#L232-L233)
+    v0 = VERTICES[i0]
+    v1 = VERTICES[i0 + 1]
+    if v0[0] == v1[0] and v0[1] == v1[1]:
+        print(f'skip initial duplicate vertex in segment: {seg[0]}')
+        i0 += 1
+    for i in range(i0, i1):
+        if i == i_start:
+            continue
+        v = VERTICES[i]
+        x = v[0]
+        y = v[1]
+        v0 = VERTICES[i_start]
+        x0 = v0[0]
+        y0 = v0[1]
+        last = i == i1 - 1
+        if (x == x0 and y == y0) or last:
+            # found end of current polygon
+            num_verts = i - i_start
+            if last:
+                num_verts += 1
+            if num_verts > 2:
+                new_seg = (seg[0], i_start, num_verts)
+                res.append(new_seg)
+            else:
+                print(f'ignoring path with less than 3 vertices in segment: {seg[0]}')
+            # skip the loop-back vertex
+            i_start = i + 1
+    return res
+
 #-------------------------------------------------------------------------------
 # Generate a triangulated index buffer per segment
 #
 def gen_triangles():
     for l,layer in enumerate(SEGMENTS):
         for seg in layer:
-            data = earcut.flatten([VERTICES[seg[1]:seg[1]+seg[2]]]);
+            # some segments are made of multiple polygons
+            split_segs = split_segment(seg)
+            if len(split_segs) == 0:
+                print(f'skipping invalid segment (no paths with at least 3 vertices): {seg[0]}')
+                continue
+            if len(split_segs) > 1:
+                print(f'found multi-poly-segment: {seg[0]} num={len(split_segs)}')
+            # convert to 'first sequence is poly and following sequences are holes'
+            poly_and_holes = []
+            for s in split_segs:
+                poly_and_holes.append(VERTICES[s[1]:s[1]+s[2]])
+            data = earcut.flatten(poly_and_holes);
             vertices = data['vertices']
             holes = data['holes']
             dims = data['dimensions']
             tri_indices = earcut.earcut(vertices, holes, dims)
+            if 0 != earcut.deviation(vertices, holes, dims, tri_indices):
+                print(f'incorrect triangulation in segment: {seg[0]}')
             tris = []
             for i in range(int(len(tri_indices) / 3)):
                 i0 = tri_indices[i * 3 + 0]
@@ -126,7 +183,6 @@ def gen_triangles():
                 v2 = (vertices[i2 * 2 + 0], vertices[i2 * 2 + 1])
                 tris.append([v0, v1, v2])
 
-            # tris = tripy.earclip(VERTICES[seg[1]:seg[1]+seg[2]])
             # add triangles picking grid
             add_tris_to_grid(l, tris)
             # add triangle vertices to vertex buffer