Added photon map implementation from the book.

photonmap.hpp

@@ -0,0 +1,103 @@
+#ifndef PHOTONMAP_H
+#define PHOTONMAP_H
+
+/* This is the photon
+ * The power is not compressed so the
+ * size is 28 bytes
+*/
+//**********************
+typedef struct Photon {
+//**********************
+  float pos[3];                  // photon position
+  short plane;                   // splitting plane for kd-tree
+  unsigned char theta, phi;      // incoming direction
+  //float power[3];                // photon power (uncompressed)
+  unsigned char power[4];
+  float ref_index;
+} Photon;
+
+
+/* This structure is used only to locate the
+ * nearest photons
+*/
+//**********************
+typedef struct NearestPhotons {
+//**********************
+    int max; 
+    int found; 
+    int got_heap; 
+    float pos[3]; 
+    float *dist2; 
+    const Photon **index; 
+} NearestPhotons;
+
+
+/* This is the Photon_map class
+ */
+//****************
+class PhotonMap {
+//****************
+ public:
+    PhotonMap(int max_phot);
+    ~PhotonMap();
+  
+    void store(
+      const float power[3],        // photon power
+      const float pos[3],          // photon position
+      const float dir[3],
+      const float ref_index);        // photon direction
+
+    void scale_photon_power(
+      const float scale);          // 1/(number of emitted photons)
+
+    void balance(void);            // balance the kd-tree (before use!)
+
+    void irradiance_estimate(
+      float irrad[3],              // returned irradiance
+      const float pos[3],          // surface position
+      const float normal[3],       // surface normal at pos
+      const float max_dist,        // max distance to look for photons
+      const int nphotons ) const;  // number of photons to use
+
+    void locate_photons(
+      NearestPhotons *const np,    // np is used to locate the photons
+      const int index) const;      // call with index = 1
+
+    void photon_dir(
+      float *dir,                  // direction of photon (returned)
+      const Photon *p) const;      // the photon
+
+ private:
+    friend class PhotonTracer;
+
+    void balance_segment(
+      Photon **pbal, 
+      Photon **porg, 
+      const int index,
+      const int start, 
+      const int end );
+
+    void median_split(
+      Photon **p, 
+      const int start, 
+      const int end,
+      const int median, 
+      const int axis );
+  
+    Photon *photons; 
+
+    int stored_photons; 
+    int half_stored_photons; 
+    int max_photons; 
+    int prev_scale; 
+
+    float costheta[256]; 
+    float sintheta[256]; 
+    float cosphi[256]; 
+    float sinphi[256]; 
+  
+    float bbox_min[3];     // use bbox_min
+    float bbox_max[3];     // use bbox_max
+};
+
+#endif