schiff

commit 33584688448cd34c7e92be1d27269e171845e2d7
parent d630e99171576f765361549d3ec09bcd193ace57
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Thu, 29 Oct 2015 08:18:03 +0100

Add the cylinder mesh

Add the function schiff_mesh_init_cylinder that initialises a
schiff_mesh with the geometry of a cylinder discretized in N slices,
with N is a user defined parameter.

Diffstat:
M
src/schiff_mesh.c
 | 
75
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
src/schiff_mesh.h
 | 
8
+++++++-

2 files changed, 82 insertions(+), 1 deletion(-)
diff --git a/src/schiff_mesh.c b/src/schiff_mesh.c
@@ -143,6 +143,81 @@ error:
   goto exit;
 }
 
+res_T
+schiff_mesh_init_cylinder
+  (struct mem_allocator* allocator,
+   struct schiff_mesh* cylinder,
+   const unsigned nsteps)
+{
+  const double step = 2*PI / (double)nsteps;
+  size_t nverts;
+  size_t ntris;
+  unsigned i;
+  res_T res = RES_OK;
+  ASSERT(allocator && cylinder && nsteps);
+
+  darray_float_init(allocator, &cylinder->vertices);
+  darray_uint_init(allocator, &cylinder->indices);
+
+  nverts = nsteps*2/* #contour verts */ + 2/* #polar verts */;
+  ntris = nsteps*2/* #contour tris */ + 2*nsteps/* #caop tris */;
+
+  res = darray_float_resize(&cylinder->vertices, nverts*3/*#coords per vert*/);
+  if(res != RES_OK) goto error;
+  res = darray_uint_resize(&cylinder->indices, ntris*3/*#indices per tri*/);
+  if(res != RES_OK) goto error;
+
+  /* Generate the vertex coordinates */
+  FOR_EACH(i, 0, nsteps) {
+    const float theta = (float)(i* step);
+    const float x = (float)cos(theta);
+    const float y = (float)sin(theta);
+    f3(darray_float_data_get(&cylinder->vertices) + (i*2 + 0)*3, x, y, 0.f);
+    f3(darray_float_data_get(&cylinder->vertices) + (i*2 + 1)*3, x, y, 1.f);
+  }
+
+  /* "Polar" vertices */
+  f3(darray_float_data_get(&cylinder->vertices) + (i*2 + 0)*3, 0.f, 0.f, 0.f);
+  f3(darray_float_data_get(&cylinder->vertices) + (i*2 + 1)*3, 0.f, 0.f, 1.f);
+
+  /* Contour primitives */
+  FOR_EACH(i, 0, nsteps) {
+    const unsigned id = i * 2;
+    unsigned* iprim = darray_uint_data_get(&cylinder->indices) + id*3;
+
+    iprim[0] = (id + 0);
+    iprim[1] = (id + 1);
+    iprim[2] = (id + 2) % (nsteps*2);
+
+    iprim += 3;
+
+    iprim[0] = (id + 2) % (nsteps*2);
+    iprim[1] = (id + 1);
+    iprim[2] = (id + 3) % (nsteps*2);
+  }
+
+  /* Cap primitives */
+  FOR_EACH(i, 0, nsteps) {
+    const unsigned id = i* 2;
+    unsigned* iprim = darray_uint_data_get(&cylinder->indices) + (nsteps + i)*6;
+
+    iprim[0] = (nsteps * 2);
+    iprim[1] = (id + 0);
+    iprim[2] = (id + 2) % (nsteps*2);
+
+    iprim += 3;
+
+    iprim[0] = (nsteps * 2) + 1;
+    iprim[1] = (id + 3) % (nsteps*2);
+    iprim[2] = (id + 1);
+  }
+exit:
+  return res;
+error:
+  schiff_mesh_release(cylinder);
+  goto exit;
+}
+
 void
 schiff_mesh_release(struct schiff_mesh* mesh)
 {
diff --git a/src/schiff_mesh.h b/src/schiff_mesh.h
@@ -39,10 +39,16 @@ struct schiff_mesh {
 
 extern LOCAL_SYM res_T
 schiff_mesh_init_sphere
-  (struct mem_allocator* alocator,
+  (struct mem_allocator* allocator,
    struct schiff_mesh* mesh,
    const unsigned nthetas); /* # discret points along 2PI */
 
+extern LOCAL_SYM res_T
+schiff_mesh_init_cylinder
+  (struct mem_allocator* allocator,
+   struct schiff_mesh* mesh,
+   const unsigned nslices);
+
 extern LOCAL_SYM void
 schiff_mesh_release
   (struct schiff_mesh* mesh);