star-mc

commit ac7c9edf63de832c06b6059845f18a2561d98bc4
parent ac0e6a010b1acb8685d0a7b7fd56f2b25311d7d8
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Wed,  8 Apr 2015 09:13:18 +0200

Finalize the light path test

Diffstat:
M
src/smc_integrator.c
 | 
2
+-
M
src/test_smc_light_path.c
 | 
61
++++++++++++++++++++++++++++++++++++++++++++++---------------

2 files changed, 47 insertions(+), 16 deletions(-)
diff --git a/src/smc_integrator.c b/src/smc_integrator.c
@@ -124,7 +124,7 @@ smc_solve
   estimator->status.N = 0;
   estimator->type = *type;
 
-  FOR_EACH(i, 0, 4096) {
+  FOR_EACH(i, 0, 16) {
     if(estimator->nsamples == ULONG_MAX) break;
     integrand(val, dev->rng, ctx);
     type->add(estimator->value, estimator->value, val);
diff --git a/src/test_smc_light_path.c b/src/test_smc_light_path.c
@@ -44,8 +44,9 @@
 #define IMG_WIDTH 640
 #define IMG_HEIGHT 480
 #define LIGHT_PATH_DEPTH 4
-#define SKY_RADIANCE 1.f
+#define SKY_RADIANCE 0.1f
 #define ALBEDO 1.f
+#define EPSILON 1.e-3f
 
 struct cbox_desc{
   const float* vertices;
@@ -201,6 +202,30 @@ struct integrator_context {
   size_t ipixel[2]; /* Image space pixel coordinates */
 };
 
+static float
+direct_lighting(struct s3d_scene* scn, const float pos[3], const float N[3])
+{
+  const float light_pos[3] = { 200.f, 0.f, 400.f };
+  const float radiance = 20000.f;
+  struct s3d_hit hit;
+  float len;
+  float wi[3];
+  float range[2];
+
+  f3_sub(wi, light_pos, pos);
+  len = f3_normalize(wi, wi);
+
+  /* Trace shadow ray */
+  range[0] = EPSILON;
+  range[1] = len;
+  CHECK(s3d_scene_trace_ray(scn, pos, wi, range, &hit), RES_OK);
+
+  if(!S3D_HIT_NONE(&hit))
+    return 0.f;
+
+  return (radiance * (float)(ALBEDO / PI)) / (len*len) * f3_dot(wi, N);
+}
+
 static void
 light_path_integrator(void* value, struct ssp_rng* rng, void* data)
 {
@@ -233,29 +258,35 @@ light_path_integrator(void* value, struct ssp_rng* rng, void* data)
   FOR_EACH(idepth, 0, LIGHT_PATH_DEPTH) {
     struct s3d_hit hit = S3D_HIT_NULL;
     float cos_theta;
-    float offset = 1.e-6f;
+    float sample[4];
     float pdf;
-    float wi[3];
+    float pos[3];
     float N[3];
 
     CHECK(s3d_scene_trace_ray
       (ctx->scn, ray_org, ray_dir, ray_range, &hit), RES_OK);
 
-    if(!S3D_HIT_NONE(&hit)) { /* Skydome lighting */
+    if(S3D_HIT_NONE(&hit)) { /* Skydome lighting */
       L += throughput * SKY_RADIANCE;
       break;
     }
 
-    /* TODO sample the surface hemisphere at the hit position */
+    f3_normalize(N, hit.normal);
+    cos_theta = f3_dot(N, ray_dir);
+    if(cos_theta >= 0.f) f3_minus(N, N);
+    f3_add(pos, f3_mulf(pos, ray_dir, hit.distance), ray_org);
+
+    /* Direct lighting */
+    L += throughput * direct_lighting(ctx->scn, pos, N);
 
     /* New ray */
-    f3_normalize(N, hit.normal);
-    cos_theta = f3_dot(N, wi);
-    if(cos_theta < 0.f) f3_dot(f3_minus(N, N), wi);
-    f3_mulf(ray_org, ray_dir, hit.distance);
-    f3_set(ray_dir, wi);
-    ray_range[0] = offset;
-    throughput *= ALBEDO / pdf * cos_theta;
+    ssp_ran_hemisphere_cos(rng, N, sample);
+    pdf = sample[3];
+    cos_theta = f3_dot(N, sample);
+    f3_set(ray_org, pos);
+    f3_set(ray_dir, sample);
+    ray_range[0] = EPSILON;
+    throughput *= (float)(ALBEDO / PI) / pdf * cos_theta;
   }
   *(float*)value = L;
 }
@@ -273,7 +304,7 @@ main(int argc, char** argv)
   struct s3d_shape* shape;
   struct s3d_vertex_data attribs[2];
   struct smc_device* smc;
-  unsigned char* img;
+  unsigned char* img = NULL;
   size_t ix, iy;
   float pos[3];
   (void)argc, (void)argv;
@@ -343,8 +374,8 @@ main(int argc, char** argv)
         unsigned char colu;
 
         CHECK(smc_estimator_get_status(estimator, &status), RES_OK);
-        col = CLAMP(SMC_FLOAT(status.E), 0.f, 1.f);
-        colu = (unsigned char)(col * 255.f);
+        col = (float)pow(SMC_FLOAT(status.E), 1.0/2.2); /* Gamma correction */
+        colu = (unsigned char)(CLAMP(col, 0.f, 1.f) * 255.f); /* Float to U8 */
         img[ipix + 0] = colu;
         img[ipix + 1] = colu;
         img[ipix + 2] = colu;