star-3d

commit 9a9a0c47a132f0c28c6bfce1094684104b0bb97d
parent 46b98bcb8106c08106a3566d978f481170025a53
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Fri, 11 Sep 2015 14:43:54 +0200

Add and test the s3d_primitive_compute_area

Compute the area of a given primitive

Diffstat:
M
src/s3d.h
 | 
7
++++++-
M
src/s3d_primitive.c
 | 
24
++++++++++++++++++++++++
M
src/test_s3d_primitive.c
 | 
11
++++++++++-

3 files changed, 40 insertions(+), 2 deletions(-)
diff --git a/src/s3d.h b/src/s3d.h
@@ -402,6 +402,11 @@ s3d_primitive_sample
    const float u, const float v, /* Random numbers in [0, 1) */
    float st[2]); /* Sampled parametric coordinates on prim */
 
+S3D_API res_T
+s3d_primitive_compute_area
+  (const struct s3d_primitive* prim,
+   float* area);
+
 /*******************************************************************************
  * Mesh API - Manage a triangular meshes
  ******************************************************************************/
@@ -424,7 +429,7 @@ s3d_mesh_setup_indexed_vertices
  * supports a local to world transformation. Since the scene geometry is stored
  * only a single time even though it is instantiated in several positions, one
  * can use this feature to create extremely large scene
- * ******************************************************************************/
+ ******************************************************************************/
 S3D_API res_T
 s3d_instance_set_position
   (struct s3d_shape* shape,
diff --git a/src/s3d_primitive.c b/src/s3d_primitive.c
@@ -181,3 +181,27 @@ s3d_primitive_sample
   return RES_OK;;
 }
 
+res_T
+s3d_primitive_compute_area(const struct s3d_primitive* prim, float* area)
+{
+  const uint32_t* ids;
+  const float* pos;
+  const float* v0, *v1, *v2;
+  float E0[3], E1[3], N[3];
+  struct geometry* geom;
+
+  if(!prim || !area || S3D_PRIMITIVE_EQ(prim, &S3D_PRIMITIVE_NULL))
+    return RES_BAD_ARG;
+
+  geom = (struct geometry*)prim->mesh__;
+  pos = mesh_get_pos(geom->data.mesh);
+  ids = mesh_get_ids(geom->data.mesh) + prim->prim_id * 3/* #triangle ids */;
+  v0 = pos + ids[0] * 3/* #coords */;
+  v1 = pos + ids[1] * 3/* #coords */;
+  v2 = pos + ids[2] * 3/* #coords */;
+  f3_sub(E0, v1, v0);
+  f3_sub(E1, v2, v0);
+  *area = f3_len(f3_cross(N, E0, E1)) * 0.5f;
+  return RES_OK;
+}
+
diff --git a/src/test_s3d_primitive.c b/src/test_s3d_primitive.c
@@ -34,6 +34,8 @@
 #include "test_s3d_cbox.h"
 #include "test_s3d_utils.h"
 
+#include <rsys/math.h>
+
 static const float plane_verts[] = {
   0.f, 0.f, 0.f,
   1.f, 0.f, 0.f,
@@ -91,8 +93,9 @@ main(int argc, char** argv)
   struct cbox_desc desc;
   size_t nprims;
   size_t i;
-  unsigned ntris, nverts;
   float uv[2];
+  float area;
+  unsigned ntris, nverts;
   unsigned walls_id;
   (void)argc, (void)argv;
 
@@ -159,6 +162,12 @@ main(int argc, char** argv)
   CHECK(S3D_PRIMITIVE_EQ(&prim, &S3D_PRIMITIVE_NULL), 0);
   CHECK(s3d_scene_end_session(scn), RES_OK);
 
+  CHECK(s3d_primitive_compute_area(NULL, NULL), RES_BAD_ARG);
+  CHECK(s3d_primitive_compute_area(&prim, NULL), RES_BAD_ARG);
+  CHECK(s3d_primitive_compute_area(NULL, &area), RES_BAD_ARG);
+  CHECK(s3d_primitive_compute_area(&prim, &area), RES_OK);
+  CHECK(eq_epsf(area, 0.5f, 1.e-6f), 1);
+
   CHECK(s3d_primitive_sample(NULL,  1.f, 1.f, NULL), RES_BAD_ARG);
   CHECK(s3d_primitive_sample(&prim, 1.f, 1.f, NULL), RES_BAD_ARG);
   CHECK(s3d_primitive_sample(NULL, 0.f, 1.f, NULL), RES_BAD_ARG);