From 98e8216da1ecab6877223857b2d882eab2a578c0 Mon Sep 17 00:00:00 2001
From: F Zotter <fanny.zotter@helmholtz-berlin.de>
Date: Fri, 11 Oct 2024 14:48:35 +0200
Subject: [PATCH] clarifying comment for #172
---
Intern/rayx-core/src/Shader/Collision.cpp | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/Intern/rayx-core/src/Shader/Collision.cpp b/Intern/rayx-core/src/Shader/Collision.cpp
index b4aa6384..40148f0d 100644
--- a/Intern/rayx-core/src/Shader/Collision.cpp
+++ b/Intern/rayx-core/src/Shader/Collision.cpp
@@ -485,11 +485,12 @@ Collision RAYX_API findCollisionInElementCoords(Ray r, Surface surface, Cutout c
if (!inCutout(cutout, col.hitpoint.x, col.hitpoint.z)) {
col.found = false;
}
-
- // Both r.m_direction and col.normal are in element-coordinates.
- // The collision normal should point "out of the surface", i.e. in the direction that the ray came from.
- // In other words we want `dot(r.m_direction, col.normal) <= 0`.
- // Later on, we'd like to remove this hotfix, and each individual get*Collision function should already satisfy this constraint.
+ // Both r.m_direction and col.normal are in element coordinates.
+ // The collision normal should point 'outward from the surface', meaning it should oppose the ray's direction.
+ // In other words, we want `dot(r.m_direction, col.normal) <= 0`.
+ // The default normal may oppose the concave part of the overall shape
+ // Depending on whether the element is hit on a concave or convex surface,
+ // we flip the normal to ensure it points against the ray's direction.
if (dot(r.m_direction, col.normal) > 0.0) {
col.normal = col.normal * -1.0;
}