Add macro LOG_TRACE for logging ray-trace process to stderr.

1 files changed, 30 insertions, 0 deletions

diff --git a/hitlist.h b/hitlist.h
index 797644a..1ad040a 100644
--- a/hitlist.h
+++ b/hitlist.h
@@ -22,6 +22,15 @@
 //#define T_NORM_VISUAL
 #define T_DIFFUSE
 
+// log ray traces to stderr
+//#define LOG_TRACE
+
+#ifdef LOG_TRACE
+#define TRACELOG(...) (fprintf(stderr, __VA_ARGS__))
+#else
+#define TRACELOG(...)
+#endif
+
 // A world, T is color depth
 class hitlist {
     std::vector<std::shared_ptr<object>> objects;
@@ -40,6 +49,9 @@ public:
     template<typename T>
     pixel<T> color(ray3d r, random_uv_gen_3d &ruvg, uint_fast32_t max_recursion_depth = 64) const {
         assert(r.decay().is_one());
+        TRACELOG("+++ start tracing (limit=%zu)\n", max_recursion_depth);
+        TRACELOG("    ray: [%10f,%10f,%10f], decay=[%10f,%10f,%10f]\n",
+                 r.direction().x, r.direction().y, r.direction().z, r.decay().x, r.decay().y, r.decay().z);
         while (max_recursion_depth-- > 0) {
             // Detect hits
             bool hit = false;
@@ -62,6 +74,13 @@ public:
                 }
             }
             if (hit) {
+#ifdef LOG_TRACE
+                const auto _hit_p_ = r.at(hit_t);
+                const auto _rn_ = dot(r.direction(), hit_obj->normal_vector(_hit_p_));
+                TRACELOG("    hit object <%p> at [%10f,%10f,%10f], t=%10f, surface=%10f (%s)\n",
+                         hit_obj.get(), _hit_p_.x, _hit_p_.y, _hit_p_.z,
+                         hit_t, _rn_, (_rn_ < 0) ? "outside" : "inside");
+#endif
 #ifdef T_SIMPLE_COLOR
                 // simply returns color of the object
                 return hit_obj->color();
@@ -75,8 +94,12 @@ public:
 #ifdef T_DIFFUSE
                 const auto &materi = hit_obj->material();
                 if (materi.scatter(r, *hit_obj, hit_t, ruvg)) {
+                    TRACELOG("    scattered: [%10f,%10f,%10f], decay=[%10f,%10f,%10f]\n",
+                             r.direction().x, r.direction().y, r.direction().z,
+                             r.decay().x, r.decay().y, r.decay().z);
                     continue; // The ray is scatted by an object. Continue processing the scattered ray.
                 } else {
+                    TRACELOG("--- finish (absorbed by object <%p>)\n", hit_obj.get());
                     return pixel<T>::black(); // The ray is absorbed by an object completely. Return black.
                 }
 #endif
@@ -91,11 +114,18 @@ public:
                     u
             );
 #ifdef T_DIFFUSE
+#ifdef LOG_TRACE
+            const auto co = pixel8b::from(r.hit(c));
+            TRACELOG("    result: [%d, %d, %d]\n", co.r, co.g, co.b);
+            TRACELOG("--- finish (reached infinity)\n");
+#endif
             return r.hit(c);
 #else
+            TRACELOG("--- finish (hit)\n");
             return c;
 #endif
         }
+        TRACELOG("--- finish (max search depth)\n");
         return pixel<T>::black(); // reached recursion time limit, very little light
     }
 };