star-3d

commit bdc9d040617eb14b891abfb5b2816a1f8cc70236
parent af4bd70e24d11df5c83fb85bc0612a382ff405b4
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Thu, 18 Jan 2018 15:09:33 +0100

Setup the sphere "uv" on ray intersection

Diffstat:
M
src/s3d_geometry.c
 | 
23
+++++++++++++++++++----
M
src/s3d_scene_view.c
 | 
39
+++++++++++++++++++++------------------

2 files changed, 40 insertions(+), 22 deletions(-)
diff --git a/src/s3d_geometry.c b/src/s3d_geometry.c
@@ -138,6 +138,7 @@ void
 geometry_rtc_sphere_intersect(void* data, RTCRay& ray, size_t item)
 {
   float v[3];
+  float cos_theta;
   float A, B, C, D, Q, rcpA, t0, t1;
   struct geometry* geom = (struct geometry*)data;
   struct sphere sphere;
@@ -157,8 +158,6 @@ geometry_rtc_sphere_intersect(void* data, RTCRay& ray, size_t item)
   t1 = 0.5f * rcpA * (-B + Q);
 
   if(ray.tnear < t0 && t0 < ray.tfar) {
-    ray.u = 0.0f; /* TODO */
-    ray.v = 0.0f; /* TODO */
     ray.tfar = t0;
     ray.geomID = geom->irtc;
     ray.primID = (unsigned)item;
@@ -167,8 +166,6 @@ geometry_rtc_sphere_intersect(void* data, RTCRay& ray, size_t item)
     f3_sub(ray.Ng, ray.Ng, sphere.pos);
   }
   if(ray.tnear < t1 && t1 < ray.tfar) {
-    ray.u = 0.0f; /* TODO */
-    ray.v = 0.0f; /* TODO */
     ray.tfar = t1;
     ray.geomID = geom->irtc;
     ray.primID = (unsigned) item;
@@ -176,6 +173,24 @@ geometry_rtc_sphere_intersect(void* data, RTCRay& ray, size_t item)
     f3_add(ray.Ng, ray.Ng, ray.org);
     f3_sub(ray.Ng, ray.Ng, sphere.pos);
   }
+
+  /* Compute the parametric coordinate */
+  f3_normalize(ray.Ng, ray.Ng);
+  cos_theta = ray.Ng[2];
+  ray.v = (1.f - cos_theta) * 0.5f;
+  if(absf(cos_theta) == 1) {
+    ray.u = 0;
+  } 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;
+    }
+    ray.u = (float)(phi / (2*PI));
+  }
 }
 
 void
diff --git a/src/s3d_scene_view.c b/src/s3d_scene_view.c
@@ -140,23 +140,6 @@ hit_setup(struct s3d_scene_view* scnview, const RTCRay* ray, struct s3d_hit* hit
   f3_set(hit->normal, ray->Ng);
   hit->distance = ray->tfar;
 
-  hit->uv[0] = ray->u;
-  hit->uv[1] = ray->v;
-  w = 1.f - hit->uv[0] - hit->uv[1];
-  ASSERT(w <= 1.f); /* This may not occurs */
-  if(w < 0.f) { /* Handle precision error */
-    if(hit->uv[0] > hit->uv[1]) hit->uv[0] += w;
-    else hit->uv[1] += w;
-    w = 0.f;
-  }
-
-  /* Embree stores on the u and v ray parameters the barycentric coordinates of
-   * the hit with respect to the second and third triangle vertices,
-   * respectively. The following code computes the barycentric coordinates of
-   * the hit for the first and second triangle vertices */
-  hit->uv[1] = hit->uv[0];
-  hit->uv[0] = w;
-
   if((unsigned)ray->instID == RTC_INVALID_GEOMETRY_ID) {
     struct geometry* geom_shape;
     ASSERT((unsigned)ray->geomID < darray_geom_size_get(&scnview->embree2geoms));
@@ -201,6 +184,27 @@ hit_setup(struct s3d_scene_view* scnview, const RTCRay* ray, struct s3d_hit* hit
   ASSERT(((struct geometry*)hit->prim.shape__)->type == GEOM_MESH
        ||((struct geometry*)hit->prim.shape__)->type == GEOM_SPHERE);
 
+
+  hit->uv[0] = ray->u;
+  hit->uv[1] = ray->v;
+
+  if(((struct geometry*)hit->prim.shape__)->type == GEOM_MESH) {
+    w = 1.f - hit->uv[0] - hit->uv[1];
+    ASSERT(w <= 1.f); /* This may not occurs */
+    if(w < 0.f) { /* Handle precision error */
+      if(hit->uv[0] > hit->uv[1]) hit->uv[0] += w;
+      else hit->uv[1] += w;
+      w = 0.f;
+    }
+
+    /* Embree stores on the u and v ray parameters the barycentric coordinates of
+     * the hit with respect to the second and third triangle vertices,
+     * respectively. The following code computes the barycentric coordinates of
+     * the hit for the first and second triangle vertices */
+    hit->uv[1] = hit->uv[0];
+    hit->uv[0] = w;
+  }
+
   /* Flip geometric normal with respect to the flip surface flag */
   flip_surface ^= ((struct geometry*)hit->prim.shape__)->flip_surface;
   if(flip_surface) f3_minus(hit->normal, hit->normal);
@@ -1284,7 +1288,6 @@ s3d_scene_view_sample
     ASSERT(pgeom);
     geom = *pgeom;
   }
-  ASSERT(geom->type == GEOM_MESH);
 
   /* Find the sampled primitive */
   primitive->shape__ = geom;