struct mesh *mesh_fabricate_planetary_ring(float ir, float or)
{
struct mesh *m;
int i;
m = malloc(sizeof(*m));
if (!m)
return m;
memset(m, 0, sizeof(*m));
m->nvertices = 360;
m->ntriangles = m->nvertices;
m->t = malloc(sizeof(*m->t) * m->ntriangles);
if (!m->t)
goto bail;
memset(m->t, 0, sizeof(*m->t) * m->ntriangles);
m->v = malloc(sizeof(*m->v) * m->nvertices);
if (!m->v)
goto bail;
memset(m->v, 0, sizeof(*m->v) * m->nvertices);
m->l = NULL;
m->geometry_mode = MESH_GEOMETRY_TRIANGLES;
/* set up vertices */
for (i = 0; i < m->nvertices; i += 2) {
const float angle = ((2 * M_PI) * i) / m->nvertices;
m->v[i].x = cos(angle) * ir;
m->v[i].y = sin(angle) * ir;
m->v[i].z = 0.0;
m->v[i + 1].x = cos(angle) * or;
m->v[i + 1].y = sin(angle) * or;
m->v[i + 1].z = 0.0;
}
/* set up triangles */
for (i = 0; i < m->nvertices; i += 2) {
struct vertex *v1, *v2, *v3, *v4;
v1 = &m->v[i % m->nvertices];
v2 = &m->v[(i + 1) % m->nvertices];
v3 = &m->v[(i + 2) % m->nvertices];
v4 = &m->v[(i + 3) % m->nvertices];
m->t[i].v[0] = v3;
m->t[i].v[1] = v2;
m->t[i].v[2] = v1;
m->t[i + 1].v[0] = v2;
m->t[i + 1].v[1] = v3;
m->t[i + 1].v[2] = v4;
/* FIXME: set coplanar flags */
}
m->radius = mesh_compute_radius(m);
mesh_set_flat_shading_vertex_normals(m);
mesh_uv_map_planetary_ring(m);
return m;
bail:
mesh_free(m);
return NULL;
}
void mesh_distort_helper(struct mesh *m, float distortion)
{
int i;
for (i = 0; i < m->nvertices; i++) {
float dx, dy, dz;
dx = (float) snis_randn(1000) / 1000.0 * distortion - 0.5;
dy = (float) snis_randn(1000) / 1000.0 * distortion - 0.5;
dz = (float) snis_randn(1000) / 1000.0 * distortion - 0.5;
m->v[i].x += m->v[i].x * dx;
m->v[i].y += m->v[i].y * dy;
m->v[i].z += m->v[i].z * dz;
}
m->radius = mesh_compute_radius(m);
mesh_set_flat_shading_vertex_normals(m);
}
void mesh_derelict(struct mesh *m, float distortion)
{
int i;
for (i = 0; i < m->nvertices; i++) {
float dx, dy, dz;
dx = (float) (snis_randn(1000) / 1000.0 - 0.5) * distortion;
dy = (float) (snis_randn(1000) / 1000.0 - 0.5) * (distortion / 10.0) - 0.5;
dz = (float) (snis_randn(1000) / 1000.0 - 0.5) * (distortion / 10.0) - 0.5;
if (m->v[i].x < 0) {
m->v[i].x = dx;
m->v[i].y += dy;
m->v[i].z += dz;
}
}
m->radius = mesh_compute_radius(m);
for (i = 0; i < m->nvertices; i++)
m->v[i].x -= m->radius / 2.0;
m->radius = mesh_compute_radius(m);
mesh_set_flat_shading_vertex_normals(m);
mesh_graph_dev_init(m);
}
/* See: http://blog.andreaskahler.com/2009/06/creating-icosphere-mesh-in-code.html */
struct mesh *mesh_unit_icosohedron(void)
{
const double tau = (1.0 + sqrt(5.0)) / 2.0;
const double scale = 1.0 / sqrt(1.0 + tau * tau);
struct mesh *m;
m = malloc(sizeof(*m));
if (!m)
return m;
memset(m, 0, sizeof(*m));
m->nvertices = 12;
m->ntriangles = 20;
m->t = malloc(sizeof(*m->t) * m->ntriangles);
if (!m->t)
goto bail;
memset(m->t, 0, sizeof(*m->t) * m->ntriangles);
m->v = malloc(sizeof(*m->v) * m->nvertices);
if (!m->v)
goto bail;
memset(m->v, 0, sizeof(*m->v) * m->nvertices);
m->tex = 0;
/* m->tex = malloc(sizeof(*m->tex) * m->ntriangles * 3);
if (!m->tex)
goto bail;
memset(m->tex, 0, sizeof(*m->tex) * m->ntriangles * 3); */
m->l = NULL;
m->geometry_mode = MESH_GEOMETRY_TRIANGLES;
m->v[0].x = scale * -1.0;
m->v[0].y = scale * tau;
m->v[0].z = scale * 0.0;
m->v[1].x = scale * 1.0;
m->v[1].y = scale * tau;
m->v[1].z = scale * 0.0;
m->v[2].x = scale * -1.0;
m->v[2].y = scale * -tau;
m->v[2].z = scale * 0.0;
m->v[3].x = scale * 1.0;
m->v[3].y = scale * -tau;
m->v[3].z = scale * 0.0;
m->v[4].x = scale * 0.0;
m->v[4].y = scale * -1.0;
m->v[4].z = scale * tau;
m->v[5].x = scale * 0.0;
m->v[5].y = scale * 1.0;
m->v[5].z = scale * tau;
m->v[6].x = scale * 0.0;
m->v[6].y = scale * -1.0;
m->v[6].z = scale * -tau;
m->v[7].x = scale * 0.0;
m->v[7].y = scale * 1.0;
m->v[7].z = scale * -tau;
m->v[8].x = scale * tau;
m->v[8].y = scale * 0.0;
m->v[8].z = scale * -1.0;
m->v[9].x = scale * tau;
m->v[9].y = scale * 0.0;
m->v[9].z = scale * 1.0;
m->v[10].x = scale * -tau;
m->v[10].y = scale * 0.0;
m->v[10].z = scale * -1.0;
m->v[11].x = scale * -tau;
m->v[11].y = scale * 0.0;
m->v[11].z = scale * 1.0;
m->t[0].v[0] = &m->v[0];
m->t[0].v[1] = &m->v[11];
m->t[0].v[2] = &m->v[5];
m->t[1].v[0] = &m->v[0];
m->t[1].v[1] = &m->v[5];
m->t[1].v[2] = &m->v[1];
m->t[2].v[0] = &m->v[0];
m->t[2].v[1] = &m->v[1];
m->t[2].v[2] = &m->v[7];
m->t[3].v[0] = &m->v[0];
m->t[3].v[1] = &m->v[7];
m->t[3].v[2] = &m->v[10];
m->t[4].v[0] = &m->v[0];
m->t[4].v[1] = &m->v[10];
m->t[4].v[2] = &m->v[11];
m->t[5].v[0] = &m->v[1];
m->t[5].v[1] = &m->v[5];
m->t[5].v[2] = &m->v[9];
m->t[6].v[0] = &m->v[5];
m->t[6].v[1] = &m->v[11];
m->t[6].v[2] = &m->v[4];
m->t[7].v[0] = &m->v[11];
m->t[7].v[1] = &m->v[10];
m->t[7].v[2] = &m->v[2];
m->t[8].v[0] = &m->v[10];
m->t[8].v[1] = &m->v[7];
m->t[8].v[2] = &m->v[6];
m->t[9].v[0] = &m->v[7];
m->t[9].v[1] = &m->v[1];
m->t[9].v[2] = &m->v[8];
m->t[10].v[0] = &m->v[3];
m->t[10].v[1] = &m->v[9];
m->t[10].v[2] = &m->v[4];
m->t[11].v[0] = &m->v[3];
m->t[11].v[1] = &m->v[4];
m->t[11].v[2] = &m->v[2];
m->t[12].v[0] = &m->v[3];
m->t[12].v[1] = &m->v[2];
m->t[12].v[2] = &m->v[6];
m->t[13].v[0] = &m->v[3];
m->t[13].v[1] = &m->v[6];
m->t[13].v[2] = &m->v[8];
m->t[14].v[0] = &m->v[3];
m->t[14].v[1] = &m->v[8];
m->t[14].v[2] = &m->v[9];
m->t[15].v[0] = &m->v[4];
m->t[15].v[1] = &m->v[9];
m->t[15].v[2] = &m->v[5];
m->t[16].v[0] = &m->v[2];
m->t[16].v[1] = &m->v[4];
m->t[16].v[2] = &m->v[11];
m->t[17].v[0] = &m->v[6];
m->t[17].v[1] = &m->v[2];
m->t[17].v[2] = &m->v[10];
m->t[18].v[0] = &m->v[8];
m->t[18].v[1] = &m->v[6];
m->t[18].v[2] = &m->v[7];
m->t[19].v[0] = &m->v[9];
m->t[19].v[1] = &m->v[8];
m->t[19].v[2] = &m->v[1];
m->radius = mesh_compute_radius(m);
mesh_set_flat_shading_vertex_normals(m);
mesh_graph_dev_init(m);
return m;
bail:
mesh_free(m);
return NULL;
}
struct mesh *mesh_fabricate_billboard(float cx, float cy, float width, float height)
{
struct mesh *m;
m = malloc(sizeof(*m));
if (!m)
return m;
memset(m, 0, sizeof(*m));
m->nvertices = 4;
m->ntriangles = 2;
m->t = malloc(sizeof(*m->t) * m->ntriangles);
if (!m->t)
goto bail;
memset(m->t, 0, sizeof(*m->t) * m->ntriangles);
m->v = malloc(sizeof(*m->v) * m->nvertices);
if (!m->v)
goto bail;
memset(m->v, 0, sizeof(*m->v) * m->nvertices);
m->tex = malloc(sizeof(*m->tex) * m->ntriangles * 3);
if (!m->tex)
goto bail;
memset(m->tex, 0, sizeof(*m->tex) * m->ntriangles * 3);
m->l = NULL;
m->geometry_mode = MESH_GEOMETRY_TRIANGLES;
m->v[0].x = -width / 2.0f + cx;
m->v[0].y = height / 2.0f + cy;
m->v[0].z = 0;
m->v[1].x = width / 2.0f + cx;
m->v[1].y = height / 2.0f + cy;
m->v[1].z = 0;
m->v[2].x = width / 2.0f + cx;
m->v[2].y = -height / 2.0f + cy;
m->v[2].z = 0;
m->v[3].x = -width / 2.0f + cx;
m->v[3].y = -height / 2.0f + cy;
m->v[3].z = 0;
m->t[0].v[0] = &m->v[0];
m->t[0].v[1] = &m->v[2];
m->t[0].v[2] = &m->v[1];
m->t[0].flag = TRIANGLE_0_1_COPLANAR;
mesh_set_triangle_texture_coords(m, 0, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f);
m->t[1].v[0] = &m->v[0];
m->t[1].v[1] = &m->v[3];
m->t[1].v[2] = &m->v[2];
m->t[1].flag = TRIANGLE_0_2_COPLANAR;
mesh_set_triangle_texture_coords(m, 1, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f);
m->radius = mesh_compute_radius(m);
mesh_set_flat_shading_vertex_normals(m);
mesh_graph_dev_init(m);
return m;
bail:
mesh_free(m);
return NULL;
}
/* mesh_fabricate_crossbeam fabricates a mesh like so, out of 8 triangles:
* 0
* |\
* | \
* | \
* 4______| \__5
* \ \ \ \
* \ \ |3 \
* \ \ | \
* \ 1 \ | \
* \_____\|_____\6
* 7 \ |
* \ |
* \ |
* \|
* 2
* centered on origin, length axis parallel to x axis.
* length is the distance betwee 0 and 3, above, and
* radius is the distance between the center of the cross
* beam and 2,6,7,3 and 0,4,5,1.
*
* 8 triangles are needed because we need to prevent backface
* culling, so we wind one set of tris one way, and the other,
* the other.
*/
struct mesh *mesh_fabricate_crossbeam(float length, float radius)
{
struct mesh *m;
m = malloc(sizeof(*m));
if (!m)
return m;
memset(m, 0, sizeof(*m));
m->nvertices = 8;
m->ntriangles = 8;
m->t = malloc(sizeof(*m->t) * m->ntriangles);
if (!m->t)
goto bail;
memset(m->t, 0, sizeof(*m->t) * m->ntriangles);
m->v = malloc(sizeof(*m->v) * m->nvertices);
if (!m->v)
goto bail;
memset(m->v, 0, sizeof(*m->v) * m->nvertices);
m->tex = malloc(sizeof(*m->tex) * m->ntriangles * 3);
if (!m->tex)
goto bail;
memset(m->tex, 0, sizeof(*m->tex) * m->ntriangles * 3);
m->l = NULL;
m->geometry_mode = MESH_GEOMETRY_TRIANGLES;
m->v[0].x = -length / 2.0f;
m->v[0].y = radius;
m->v[0].z = 0.0f;
m->v[1].x = -length / 2.0f;
m->v[1].y = -radius;
m->v[1].z = 0.0f;
m->v[2].x = length / 2.0f;
m->v[2].y = -radius;
m->v[2].z = 0.0f;
m->v[3].x = length / 2.0f;
m->v[3].y = radius;
m->v[3].z = 0.0f;
m->v[4].x = -length / 2.0f;
m->v[4].y = 0.0f;
m->v[4].z = radius;
m->v[5].x = -length / 2.0f;
m->v[5].y = 0.0f;
m->v[5].z = -radius;
m->v[6].x = length / 2.0f;
m->v[6].y = 0.0f;
m->v[6].z = -radius;
m->v[7].x = length / 2.0f;
m->v[7].y = 0.0f;
m->v[7].z = radius;
m->t[0].v[0] = &m->v[0];
m->t[0].v[1] = &m->v[1];
m->t[0].v[2] = &m->v[2];
mesh_set_triangle_texture_coords(m, 0, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f);
m->t[1].v[0] = &m->v[2];
m->t[1].v[1] = &m->v[3];
m->t[1].v[2] = &m->v[0];
mesh_set_triangle_texture_coords(m, 1, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f);
m->t[2].v[0] = &m->v[4];
m->t[2].v[1] = &m->v[5];
m->t[2].v[2] = &m->v[6];
mesh_set_triangle_texture_coords(m, 2, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f);
m->t[3].v[0] = &m->v[6];
m->t[3].v[1] = &m->v[7];
m->t[3].v[2] = &m->v[4];
mesh_set_triangle_texture_coords(m, 3, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f);
m->t[4].v[0] = &m->v[2];
m->t[4].v[1] = &m->v[1];
m->t[4].v[2] = &m->v[0];
mesh_set_triangle_texture_coords(m, 4, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f);
m->t[5].v[0] = &m->v[0];
m->t[5].v[1] = &m->v[3];
m->t[5].v[2] = &m->v[2];
mesh_set_triangle_texture_coords(m, 5, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f);
m->t[6].v[0] = &m->v[6];
m->t[6].v[1] = &m->v[5];
m->t[6].v[2] = &m->v[4];
mesh_set_triangle_texture_coords(m, 6, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f);
m->t[7].v[0] = &m->v[4];
m->t[7].v[1] = &m->v[7];
m->t[7].v[2] = &m->v[6];
mesh_set_triangle_texture_coords(m, 7, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f);
mesh_compute_radius(m);
mesh_set_flat_shading_vertex_normals(m);
mesh_graph_dev_init(m);
return m;
bail:
mesh_free(m);
return NULL;
}
/* fabricate a tube of length h, radius r, with nfaces, parallel to x axis */
struct mesh *mesh_tube(float h, float r, float nfaces)
{
struct mesh *m;
int ntris = nfaces * 2;
int nvertices = nfaces * 2;
int i, j;
float angle, da;
float l = h / 2.0;
m = allocate_mesh_for_copy(ntris, nvertices, 0, 1);
if (!m)
return m;
m->geometry_mode = MESH_GEOMETRY_TRIANGLES;
da = 2 * M_PI / (float) nfaces;
angle = 0.0;
for (i = 0; i < nvertices; i += 2) {
m->v[i].x = -l;
m->v[i].y = r * cos(angle);
m->v[i].z = r * -sin(angle);
m->v[i + 1].x = l;
m->v[i + 1].y = m->v[i].y;
m->v[i + 1].z = m->v[i].z;
angle += da;
}
m->nvertices = nvertices;
for (i = 0; i < ntris; i += 2) {
m->t[i].v[2] = &m->v[i % nvertices];
m->t[i].v[1] = &m->v[(i + 1) % nvertices];
m->t[i].v[0] = &m->v[(i + 2) % nvertices];
m->t[i + 1].v[2] = &m->v[(i + 2) % nvertices];
m->t[i + 1].v[1] = &m->v[(i + 1) % nvertices];
m->t[i + 1].v[0] = &m->v[(i + 3) % nvertices];
}
m->ntriangles = ntris;
for (i = 0; i < ntris; i++) {
union vec3 normal;
normal = compute_triangle_normal(&m->t[i]);
m->t[i].n.x = normal.v.x;
m->t[i].n.y = normal.v.y;
m->t[i].n.z = normal.v.z;
for (j = 0; j < 3; j++) {
union vec3 normal = { { 0, -m->t[i].v[j]->y, -m->t[i].v[j]->z } };
vec3_normalize_self(&normal);
m->t[i].vnormal[j].x = normal.v.x;
m->t[i].vnormal[j].y = normal.v.y;
m->t[i].vnormal[j].z = normal.v.z;
}
}
mesh_set_flat_shading_vertex_normals(m);
for (i = 0; i < ntris; i += 2) {
mesh_set_triangle_texture_coords(m, i,
0.0, (float) ((int) ((i + 2) / 2)) * 1.0 / (float) nfaces,
1.0, (float) ((int) (i / 2)) / (float) nfaces,
0.0, (float) ((int) (i / 2)) / (float) nfaces);
mesh_set_triangle_texture_coords(m, i + 1,
1.0, (float) ((int) ((i + 2) / 2)) / (float) nfaces,
1.0, (float) ((int) (i / 2)) / (float) nfaces,
0.0, (float) ((int) ((i + 2) / 2)) / (float) nfaces);
}
m->nlines = 0;
m->radius = mesh_compute_radius(m);
mesh_graph_dev_init(m);
return m;
}
