# Intersection with Triangles Aligned in the Same Plane

Firstly, thanks for the great library! Really enjoying playing around with it so far.

I have a question related to how Embree handles triangles that are aligned (and overlapping) in the same plane. To illustrate this please refer to the 2D examples below. In case 1, one triangle mesh (b) is enclosed within another (a) and one side is aligned and overlapping. In case 2, the triangle meshes (a and b) are side by side but share a side.

# bvh statistic

Is it possible to get the BVH statistics, like total levels, no. of bonding volumes generated, no. of bvh traversals, bvh traversals per ray etc. I am trying benchmark the performance of a few other algorithms.

Thanks

# Getting "tnear" and "tfar" of a UserGeometry BoundingBox?

Is is possible to get the points (or the parametric variables) where the ray crosses the user geometry BoundingBox while inside the intersection function? Right now the public API only provides the "UserObject" ptr, the ray and the "geom_id".

# Multi-threading in Embree 2.0

Which functions in Embree 2.0 are implemented to use multiple threads? When I do rtcStartThreads() which of the functions are affected? Specifically are the intersect and occluded functions multi-threaded?

Thanks,

Ritwik

# rtcCommit not working

Below is the code that I am using, my code gets stuck at rtcCommit(). I am not sure why this is happening...any clue would be great help.

Thanks

# Barycentric coordinates u, v

Hi,

After intersecting a ray with a scene, what is the proper way to use the u, v  coordinates to calculate the world coordinates (x, y, z) of the hit? I believe from the geomID and primID, I can identify the triangle which is hit and its corresponding v0, v1, v2. But now what do I do?

# Intersect and occluded in Embree 2.0

Can anybody tell me the proper way to intersect a ray with a piece of geometry. I have been able to create the geometry but how am I supposed to get the hit information from intersection? What are the primitive IDs in Ray and why are there 2 of them?

Thanks,

Ritwik

# Embree 2.0 documentation

Hello,
I am trying to implement a ray tracer using the Embree 2.0 (I cannot use a more recent version because of dependency). I was looking for documentation of the API for 2.0 but could not find any. Please help.

Thanks,

Ritwik

# rtcSetTransform instance positioning

Hi,

How do the positioning of instances exactly work? I know that rtcSetTransform convert from local to world space, but positioning seems very weird. Let me explain what I do and what it does...

I create a cube at origin (0,0,0) and instantiate it at (10,0,0) all works well. If I rotate the instance, all works well.

# rtcSetTransform

Hi, first let me say thank you for such a state-of-the-art kernel for CPU, it is by far the best ever developed.

I'm trying to rotate an instance by setting the RTCMatrix parameter of rtcSetTransform but I can't seen to figure it out. I know it is an affine transformation matrix, but no matter what I do, it never rotate properly.

My question, is there an example available showing the members of the matrix used for rotation? I know you have a tutorial but it only set the matrix to the identity matrix and use the last members as a position change only, no rotation.