workaround for incorrect ray intersections with open cones #140
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diff --git a/CSG/csg_intersect_leaf_newcone.h b/CSG/csg_intersect_leaf_newcone.h
index 740ac5a..9801725 100644
--- a/CSG/csg_intersect_leaf_newcone.h
+++ b/CSG/csg_intersect_leaf_newcone.h
@@ -101,2 +101,2 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
- const float t_cand = fminf(roots) ;
-
+ const float t_cand = fminf(roots) ;
+
@@ -104 +104 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
- float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z)*tth2));
+ float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2));
@@ -111,2 +110,0 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
-
-
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diff --git a/CSG/csg_intersect_leaf_newcone.h b/CSG/csg_intersect_leaf_newcone.h
index 740ac5a..9801725 100644
--- a/CSG/csg_intersect_leaf_newcone.h
+++ b/CSG/csg_intersect_leaf_newcone.h
@@ -101,2 +101,2 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
- const float t_cand = fminf(roots) ;
-
+ const float t_cand = fminf(roots) ;
+
@@ -104 +104 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
- float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z)*tth2));
+ float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2));
@@ -111,2 +110,0 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
-
-
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diff --git a/CSG/csg_intersect_leaf_newcone.h b/CSG/csg_intersect_leaf_newcone.h
index 2967d49..3bc042d 100644
--- a/CSG/csg_intersect_leaf_newcone.h
+++ b/CSG/csg_intersect_leaf_newcone.h
@@ -101 +101 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
- const float t_cand = fminf(roots) ;
+ const float t_cand = fminf(roots);
@@ -111,2 +110,0 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
-
-
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diff --git a/CSG/csg_intersect_leaf_newcone.h b/CSG/csg_intersect_leaf_newcone.h
index 2967d49..3bc042d 100644
--- a/CSG/csg_intersect_leaf_newcone.h
+++ b/CSG/csg_intersect_leaf_newcone.h
@@ -101 +101 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
- const float t_cand = fminf(roots) ;
+ const float t_cand = fminf(roots);
@@ -111,2 +110,0 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
-
-
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CSG/csg_intersect_leaf_newcone.h
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| } | ||
| isect.w = t_cand ; | ||
| } | ||
| const float t_cand = fminf(roots) ; |
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| const float t_cand = fminf(roots) ; | |
| const float t_cand = fminf(roots); |
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diff --git a/CSG/csg_intersect_leaf_newcone.h b/CSG/csg_intersect_leaf_newcone.h
index 2967d49..3bc042d 100644
--- a/CSG/csg_intersect_leaf_newcone.h
+++ b/CSG/csg_intersect_leaf_newcone.h
@@ -101 +101 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
- const float t_cand = fminf(roots) ;
+ const float t_cand = fminf(roots);
@@ -111,2 +110,0 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
-
-
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CSG/csg_intersect_leaf_newcone.h
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| } | ||
| isect.w = t_cand ; | ||
| } | ||
| const float t_cand = fminf(roots) ; |
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| const float t_cand = fminf(roots) ; | |
| const float t_cand = fminf(roots); |
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Please remove the line(s)
- 111
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Pull request overview
This pull request attempts to fix incorrect ray intersections with open cones by simplifying the intersection logic. However, the implementation introduces several critical bugs that will cause incorrect rendering behavior.
Key changes:
- Removed validation logic that checks if
t_candrepresents a valid intersection - Eliminated cap-specific normal calculations (normals for end cap intersections)
- Simplified to always compute cone surface normals regardless of intersection type
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CSG/csg_intersect_leaf_newcone.h
Outdated
| float3 intersection_point = make_float3(o.x + t_cand * d.x, o.y + t_cand * d.y, o.z + t_cand * d.z); | ||
| float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2)); | ||
|
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| isect.x = n.x; | ||
| isect.y = n.y; | ||
| isect.z = n.z; | ||
| isect.w = t_cand; |
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The valid_isect output parameter is never set, which will cause incorrect behavior in calling code. All other intersection functions (e.g., intersect_leaf_sphere, intersect_leaf_cylinder) validate t_cand and set valid_isect = t_cand > t_min && t_cand < RT_DEFAULT_MAX before populating the intersection result. Without this check, invalid intersections (when all roots are disqualified and t_cand == RT_DEFAULT_MAX) will be processed as valid.
| float3 intersection_point = make_float3(o.x + t_cand * d.x, o.y + t_cand * d.y, o.z + t_cand * d.z); | |
| float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2)); | |
| isect.x = n.x; | |
| isect.y = n.y; | |
| isect.z = n.z; | |
| isect.w = t_cand; | |
| valid_isect = t_cand > t_min && t_cand < RT_DEFAULT_MAX ; | |
| if (valid_isect) | |
| { | |
| float3 intersection_point = make_float3(o.x + t_cand * d.x, o.y + t_cand * d.y, o.z + t_cand * d.z); | |
| float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2)); | |
| isect.x = n.x; | |
| isect.y = n.y; | |
| isect.z = n.z; | |
| isect.w = t_cand; | |
| } | |
| else | |
| { | |
| isect = make_float4(0.f, 0.f, 0.f, RT_DEFAULT_MAX); | |
| } |
CSG/csg_intersect_leaf_newcone.h
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| float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2)); | ||
|
|
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The normal calculation always uses the cone surface formula, even when the intersection is with a cap (t_cand == t_cap1 or t_cap2). The removed code correctly handled cap normals as (0, 0, ±1), which point along the z-axis. Using the cone surface normal formula for cap intersections will produce incorrect normals. Cap intersections should be detected and handled separately, as done in the original code and in intersect_leaf_cylinder (line 79).
| float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2)); | |
| float3 n; | |
| if (t_cand == t_cap1) { | |
| n = make_float3(0.f, 0.f, -1.f); // lower cap normal | |
| } else if (t_cand == t_cap2) { | |
| n = make_float3(0.f, 0.f, 1.f); // upper cap normal | |
| } else { | |
| n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2)); | |
| } |
CSG/csg_intersect_leaf_newcone.h
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| float3 intersection_point = make_float3(o.x + t_cand * d.x, o.y + t_cand * d.y, o.z + t_cand * d.z); | ||
| float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2)); | ||
|
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| isect.x = n.x; | ||
| isect.y = n.y; | ||
| isect.z = n.z; | ||
| isect.w = t_cand; |
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When t_cand == RT_DEFAULT_MAX (no valid intersection found), the normal calculation can produce undefined results. Specifically, if the intersection point computed with RT_DEFAULT_MAX happens to be at or near the cone apex (where x=0, y=0, z=z0), the vector passed to normalize() will be zero or near-zero, causing normalization of a zero-length vector. The computation should only proceed if t_cand represents a valid intersection (i.e., t_cand < RT_DEFAULT_MAX).
| float3 intersection_point = make_float3(o.x + t_cand * d.x, o.y + t_cand * d.y, o.z + t_cand * d.z); | |
| float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2)); | |
| isect.x = n.x; | |
| isect.y = n.y; | |
| isect.z = n.z; | |
| isect.w = t_cand; | |
| if (t_cand < RT_DEFAULT_MAX) | |
| { | |
| float3 intersection_point = make_float3(o.x + t_cand * d.x, o.y + t_cand * d.y, o.z + t_cand * d.z); | |
| float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2)); | |
| isect.x = n.x; | |
| isect.y = n.y; | |
| isect.z = n.z; | |
| isect.w = t_cand; | |
| valid_isect = true; | |
| } | |
| else | |
| { | |
| isect.x = 0.f; | |
| isect.y = 0.f; | |
| isect.z = 0.f; | |
| isect.w = RT_DEFAULT_MAX; | |
| valid_isect = false; | |
| } |
|
@ggalgoczi Are you going to run this workaround by Simon? |
|
Will ask him about it later on, after finished with the photon leakage. However this is a special case of a cone in question here. I think for now we should not merge since it opens up even closed cones. |
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diff --git a/CSG/csg_intersect_leaf_newcone.h b/CSG/csg_intersect_leaf_newcone.h
index 371c713..a4e7aa3 100644
--- a/CSG/csg_intersect_leaf_newcone.h
+++ b/CSG/csg_intersect_leaf_newcone.h
@@ -101,2 +101,2 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
- const float t_cand = fminf(roots) ;
-
+ const float t_cand = fminf(roots) ;
+
@@ -107 +107,2 @@ void intersect_leaf_newcone( bool& valid_isect, float4& isect, const quad& q0, c
- float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z)*tth2));
+ float3 n =
+ normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2));
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| const float t_cand = fminf(roots) ; | ||
|
|
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| const float t_cand = fminf(roots) ; | |
| const float t_cand = fminf(roots) ; | |
| } | ||
| isect.w = t_cand ; | ||
| float3 intersection_point = make_float3(o.x + t_cand * d.x, o.y + t_cand * d.y, o.z + t_cand * d.z); | ||
| float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z)*tth2)); |
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| float3 n = normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z)*tth2)); | |
| float3 n = | |
| normalize(make_float3(intersection_point.x, intersection_point.y, (z0 - intersection_point.z) * tth2)); |
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