Fix texture boundaries in makeRing

Texture coordinates didn't go all the way up to 1 at the seams.
This caused "ghost" textures to appear between vertices on either side
of the seams.  The fix is to duplicate vertices at the seams, one with
texture coord=0 and one with texture coord=1.

Author: wigie

lib/glow/mesh.js

@@ -284,7 +284,7 @@
             var x=0, z=R2, newx, newz
             //var k = 1/Math.cos(dphi/2) // multiply z by k to stretch along the joint; only 1.00121, so approximate by 1
             var shape = [] // list of x,z points in the xz plane representing the shape at a joint
-            for (var i=0; i<N; i++) {
+            for (var i=0; i<N+1; i++) {
             	//shape.push(vec(x,0,k*z-k*R2)) 
             	shape.push(vec(x,0,z-R2)) // oval starts at outer edge of ring
             	newx = x*cosd + z*sind
@@ -295,7 +295,7 @@
 
             var y=0, z=R1+R2, newy, newz
         	var normals = []
-            for (var c=0; c<NC; c++) {
+            for (var c=0; c<NC+1; c++) {
             	var r = vec(0, y, z) // vector from origin to outer edge of oval cross section
                 normals.push(r) // use normal to contain the vector from origin to outer edge of the oval
 
@@ -306,17 +306,19 @@
             }
 
             var m = new Mesh()
-            for (var c=0; c<NC; c++) {
-             	for (var i=0; i<N; i++) {
-             		var inext = (i+1) % N
+            var offset = N+1
+            for (var c=0; c<NC+1; c++) {
+                var s = c*offset
+             	for (var i=0; i<offset; i++) {
+             		var inext = (i+1) % offset
              		var cnext = (c+1) % NC
              		var v0 = shape[i]
              		m.pos.push( v0.x,v0.y,v0.z )
 
              		v0 = normals[c]
              		m.normal.push( v0.x,v0.y,v0.z )
 
-          		    m.color.push( 1,1,1 )
+          		    m.color.push( 1, 1, 1 )
           		    m.opacity.push( 1 )
           		    m.shininess.push( 1 )
           		    m.emissive.push( 0 )
@@ -326,9 +328,11 @@
           		    v0 = shape[inext].sub(shape[i])
           		    m.bumpaxis.push( v0.x,v0.y,v0.z )
 
-          		    m.index.push( N*c+i,N*cnext+i,N*cnext+inext,   N*c+i,N*cnext+inext,N*c+inext )
-             	}
+          		    m.index.push( s+i,s+i+offset,s+i+offset+1,   s+i,s+i+offset+1,s+i+1 )
+                 }
+                 m.index.length -= 6 // discard last set of indices
             }
+            m.index.length -= 6*(offset-1) // discard entire last band of indices
             return m
         },
 
@@ -391,7 +395,7 @@
              		v0 = normals[c*N+i]
              		m.normal.push( v0.x,v0.y,v0.z )
 
-          		    m.color.push( 1,1,1 )
+          		    m.color.push( 1, 1, 1 )
           		    m.opacity.push( 1 )
           		    m.shininess.push( 1 )
           		    m.emissive.push( 0 )