started on the BVH build

diff --git a/src/bvh.c b/src/bvh.c
new file mode 100644 (file)
index 0000000..dced9d9
--- /dev/null
+++ b/src/bvh.c
@@ -0,0 +1,58 @@
+#include <stdlib.h>
+#include <float.h>
+#include "bvh.h"
+
+int build_bvh_sah(struct bvhnode *tree)
+{
+       int i, j;
+       float sarea;
+
+       if(tree->num_faces < 5 || tree->left || tree->right) return 0;
+
+       dx = tree->aabb.vmax.x - tree->aabb.vmin.x;
+       dy = tree->aabb.vmax.y - tree->aabb.vmin.y;
+       dz = tree->aabb.vmax.z - tree->aabb.vmin.z;
+
+       if((sarea = surf_area(dx, dy, dz)) <= 0.0f) return 0;
+
+       tree->axis = dx > dy ? (dx > dz ? dx : dz) : (dy > dz ? dy : dz);
+
+       /* TODO */
+}
+
+void free_bvh_tree(struct bvhnode *tree)
+{
+       free(tree->faces);
+       free_bvh_tree(tree->left);
+       free_bvh_tree(tree->right);
+       free(tree);
+}
+
+int ray_bvhnode(cgm_ray *ray, struct bvhnode *bn, float tmax, struct rayhit *hit)
+{
+       int i, res = 0;
+       struct rayhit hit0;
+
+       if(!ray_aabox_any(ray, &bn->aabb, tmax)) {
+               return 0;
+       }
+
+       if(!hit) {
+               for(i=0; i<bn->num_faces; i++) {
+                       if(ray_triangle(ray, bn->faces + i, tmax, 0)) {
+                               return 1;
+                       }
+               }
+               return 0;
+       }
+
+       hit0.t = FLT_MAX;
+       for(i=0; i<bn->num_faces; i++) {
+               if(ray_triangle(ray, bn->faces + i, tmax, hit) && hit->t < hit0.t) {
+                       hit0 = *hit;
+                       res = 1;
+               }
+       }
+       *hit = hit0;
+       return res;
+}

diff --git a/src/bvh.h b/src/bvh.h
new file mode 100644 (file)
index 0000000..03bc726
--- /dev/null
+++ b/src/bvh.h
@@ -0,0 +1,24 @@
+#ifndef BVH_H_
+#define BVH_H_
+
+#include "geom.h"
+
+struct bvhnode {
+       struct aabox aabb;
+       int axis;
+
+       struct triangle *faces;
+       int num_faces, max_faces;
+
+       struct bvhnode *left, *right;
+};
+
+/* build_bvh* needs to be called with a pointer to a single-node tree,
+ * containing all the faces, left/right as null, and a pre-computed aabb
+ */
+int build_bvh_sah(struct bvhnode *tree);
+void free_bvh_tree(struct bvhnode *tree);
+
+int ray_bvhnode(cgm_ray *ray, struct bvhnode *bn, float tmax, struct rayhit *hit);
+
+#endif /* BVH_H_ */

diff --git a/src/geom.c b/src/geom.c
index ef15156..07f7a9b 100644 (file)
--- a/src/geom.c
+++ b/src/geom.c
@@ -1,17 +1,6 @@
 #include <float.h>
 #include "geom.h"
 
-void free_bvh_tree(struct bvhnode *tree)
-{
-       struct bvhnode *node, *tmp;
-
-       free(tree->faces);
-
-       free_bvh_tree(tree->left);
-       free_bvh_tree(tree->right);
-       free(tree);
-}
-
 int ray_triangle(cgm_ray *ray, struct triangle *tri, float tmax, struct rayhit *hit)
 {
        float t, ndotdir;
@@ -79,31 +68,31 @@ int ray_aabox_any(cgm_ray *ray, struct aabox *box, float tmax)
        return 1;
 }
 
-int ray_bvhnode(cgm_ray *ray, struct bvhnode *bn, float tmax, struct rayhit *hit)
+void aabox_union(struct aabox *res, struct aabox *a, struct aabox *b)
 {
-       int i, res = 0;
-       struct rayhit hit0;
+       res->vmin.x = a->vmin.x < b->vmin.x ? a->vmin.x : b->vmin.x;
+       res->vmax.x = a->vmax.x > b->vmax.x ? a->vmax.x : b->vmax.x;
+       res->vmin.y = a->vmin.y < b->vmin.y ? a->vmin.y : b->vmin.y;
+       res->vmax.y = a->vmax.y > b->vmax.y ? a->vmax.y : b->vmax.y;
+       res->vmin.z = a->vmin.z < b->vmin.z ? a->vmin.z : b->vmin.z;
+       res->vmax.z = a->vmax.z > b->vmax.z ? a->vmax.z : b->vmax.z;
+}
 
-       if(!ray_aabox_any(ray, &bn->aabb, tmax)) {
-               return 0;
-       }
+float aabox_surf_area(struct aabox *box)
+{
+       float dx, dy, dz;
 
-       if(!hit) {
-               for(i=0; i<bn->num_faces; i++) {
-                       if(ray_triangle(ray, bn->faces + i, tmax, 0)) {
-                               return 1;
-                       }
-               }
-               return 0;
-       }
+       dx = box->vmax.x - box->vmin.x;
+       dy = box->vmax.y - box->vmin.y;
+       dz = box->vmax.z - box->vmin.z;
 
-       hit0.t = FLT_MAX;
-       for(i=0; i<bn->num_faces; i++) {
-               if(ray_triangle(ray, bn->faces + i, tmax, hit) && hit->t < hit0.t) {
-                       hit0 = *hit;
-                       res = 1;
-               }
+       return surf_area(dx, dy, dz);
+}
+
+float surf_area(float dx, float dy, float dz)
+{
+       if(dx <= 0 || dy <= 0 || dz <= 0) {
+               return 0.0f;
        }
-       *hit = hit0;
-       return res;
+       return (dx * dy + dx * dz + dy * dz) * 2.0f;
 }

diff --git a/src/geom.h b/src/geom.h
index 7f71094..2233c67 100644 (file)
--- a/src/geom.h
+++ b/src/geom.h
@@ -20,15 +20,6 @@ struct aabox {
        cgm_vec3 vmin, vmax;
 };
 
-struct bvhnode {
-       struct aabox aabb;
-
-       struct triangle *faces;
-       int num_faces;
-
-       struct bvhnode *left, *right;
-};
-
 struct rayhit {
        float t;
        struct vertex v;
@@ -36,10 +27,11 @@ struct rayhit {
        struct material *mtl;
 };
 
-void free_bvh_tree(struct bvhnode *tree);
-
 int ray_triangle(cgm_ray *ray, struct triangle *tri, float tmax, struct rayhit *hit);
 int ray_aabox_any(cgm_ray *ray, struct aabox *box, float tmax);
-int ray_bvhnode(cgm_ray *ray, struct bvhnode *bn, float tmax, struct rayhit *hit);
+
+void aabox_union(struct aabox *res, struct aabox *a, struct aabox *b);
+float aabox_surf_area(struct aabox *box);
+float surf_area(float dx, float dy, float dz);
 
 #endif /* GEOM_H_ */

diff --git a/src/level.h b/src/level.h
index c65fc2d..010e050 100644 (file)
--- a/src/level.h
+++ b/src/level.h
@@ -2,7 +2,7 @@
 #define LEVEL_H_
 
 #include "rt.h"
-#include "geom.h"
+#include "bvh.h"
 
 struct level {
        struct bvhnode *st_root;