star-sp

commit 1d574ef813d6c6d171aa08e882b65bba02cb7e82
parent 424ed34658422dc46808cbfdc8b36d4e309609ab
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Thu, 23 Jul 2015 16:00:06 +0200

Test the uniform random triangle sampling

Ensure the uniformity of the triangle sampling

Diffstat:
M
src/test_ssp_ran_triangle.c
 | 
20
++++++++++++++++++--

1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/src/test_ssp_ran_triangle.c b/src/test_ssp_ran_triangle.c
@@ -42,7 +42,9 @@ main(int argc, char** argv)
   float A[3], B[3], C[3];
   float v0[3], v1[3], v2[3], v3[3], v4[3], v5[3];
   float plane[4];
-  int i;
+  size_t counter[2];
+  size_t nsteps;
+  size_t i;
   (void)argc, (void)argv;
 
   mem_init_proxy_allocator(&allocator, &mem_default_allocator);
@@ -73,7 +75,7 @@ main(int argc, char** argv)
     CHECK(eq_epsf(f3_dot(plane, samps[i]), -plane[3], 1.e-6f), 1);
 
     f3_sub(tmp0, samps[i], A);
-    dot = f3_dot(f3_cross(tmp0, tmp0, v0), f3_cross(tmp1, v1, v0 ));
+    dot = f3_dot(f3_cross(tmp0, tmp0, v0), f3_cross(tmp1, v1, v0));
     CHECK(signf(dot), 1.f );
     f3_sub(tmp0, samps[i], B);
     dot = f3_dot(f3_cross(tmp0, tmp0, v2), f3_cross(tmp1, v3, v2));
@@ -86,6 +88,20 @@ main(int argc, char** argv)
     CHECK(eq_epsf(1.f / area, ssp_ran_triangle_uniform_pdf(A, B, C), 1.e-6f), 1);
   }
 
+  nsteps = 10000;
+  counter[0] = counter[1] = 0;
+  f3(A, -1.f, 0.f, 0.f);
+  f3(B,  1.f, 0.f, 0.f);
+  f3(C,  0.f, 1.f, 0.f);
+  FOR_EACH(i, 0, nsteps) {
+    ssp_ran_triangle_uniform(rng, A, B, C, samps[0]);
+    if(samps[0][0] < 0.f)
+      counter[0] += 1;
+    else
+      counter[1] += 1;
+  }
+  CHECK(labs((long)(counter[1] - counter[0])) < 100, 1);
+
   ssp_rng_ref_put(rng);
   check_memory_allocator(&allocator);
   mem_shutdown_proxy_allocator(&allocator);