From 19e18b4089285d77671424110a807b409a5aa46e Mon Sep 17 00:00:00 2001
From: Alexander Rose <alexander.rose@weirdbyte.de>
Date: Tue, 21 Apr 2020 11:36:41 -0700
Subject: [PATCH] MC: ensure winding-order and normals dir are same for neg/pos
iso-level
---
src/mol-geo/util/marching-cubes/algorithm.ts | 23 +++++++++++++++-----
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/src/mol-geo/util/marching-cubes/algorithm.ts b/src/mol-geo/util/marching-cubes/algorithm.ts
index 2e4b5e4de..2c79d5ae9 100644
--- a/src/mol-geo/util/marching-cubes/algorithm.ts
+++ b/src/mol-geo/util/marching-cubes/algorithm.ts
@@ -196,11 +196,16 @@ class MarchingCubesState {
const n1y = sfg(sf, hi, Math.max(0, hj - 1), hk) - sfg(sf, hi, Math.min(this.nY - 1, hj + 1), hk);
const n1z = sfg(sf, hi, hj, Math.max(0, hk - 1)) - sfg(sf, hi, hj, Math.min(this.nZ - 1, hk + 1));
- this.builder.addNormal(
- n0x + t * (n0x - n1x),
- n0y + t * (n0y - n1y),
- n0z + t * (n0z - n1z)
- );
+ const nx = n0x + t * (n0x - n1x);
+ const ny = n0y + t * (n0y - n1y);
+ const nz = n0z + t * (n0z - n1z);
+
+ // ensure normal-direction is the same for negative and positive iso-levels
+ if (this.isoLevel >= 0) {
+ this.builder.addNormal(nx, ny, nz);
+ } else {
+ this.builder.addNormal(-nx, -ny, -nz);
+ }
return id;
}
@@ -255,7 +260,13 @@ class MarchingCubesState {
const triInfo = TriTable[tableIndex];
for (let t = 0; t < triInfo.length; t += 3) {
- this.builder.addTriangle(this.vertList, triInfo[t], triInfo[t + 1], triInfo[t + 2], edgeFilter);
+ const l = triInfo[t], m = triInfo[t + 1], n = triInfo[t + 2];
+ // ensure winding-order is the same for negative and positive iso-levels
+ if (this.isoLevel >= 0) {
+ this.builder.addTriangle(this.vertList, l, m, n, edgeFilter);
+ } else {
+ this.builder.addTriangle(this.vertList, n, m, l, edgeFilter);
+ }
}
}
}
\ No newline at end of file
--
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