star-3d

commit 1ff1455cfd740725b9a22883bea29dd22cde8513
parent f38664cfbe50a90f2f022bc8b091b207bdc30104
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Mon, 22 Jan 2018 09:07:35 +0100

Upd the computation of the uv parameter on sphere intersection

Diffstat:
M
src/s3d.h
 | 
4
+++-
M
src/s3d_geometry.c
 | 
8
++------

2 files changed, 5 insertions(+), 7 deletions(-)
diff --git a/src/s3d.h b/src/s3d.h
@@ -447,7 +447,9 @@ s3d_triangle_get_vertex_attrib
    struct s3d_attrib* attrib);
 
 /*******************************************************************************
- * Sphere API - Manage a spherical shape
+ * Sphere API - Manage a spherical shape. By default, the sphere normals point
+ * outward the sphere. One can use the s3d_shape_flip_surface function to
+ * revert them.
  ******************************************************************************/
 S3D_API res_T
 s3d_shape_create_sphere
diff --git a/src/s3d_geometry.c b/src/s3d_geometry.c
@@ -183,12 +183,8 @@ geometry_rtc_sphere_intersect(void* data, RTCRay& ray, size_t item)
   } else if(eq_epsf(ray.Ng[0], 0.f, 1.e-6f)) {
     ray.u = ray.Ng[1] > 0 ?  0.25f : 0.75f;
   } else {
-    double phi = atan(ray.Ng[1] / ray.Ng[0]);
-    if(ray.Ng[0] < 0) {
-      phi = phi + PI;
-    } else if(ray.Ng[1] < 0) {
-      phi = 2*PI + phi;
-    }
+    double phi = atan2f(ray.Ng[1],  ray.Ng[0]); /* phi in [-PI, PI] */
+    if(phi < 0) phi = 2*PI + phi; /* phi in [0, 2PI] */
     ray.u = (float)(phi / (2*PI));
   }
 }