void mesh_map_xy_to_uv(struct mesh *m)
{
float u0, v0, u1, v1, u2, v2, r;
int i;
r = mesh_calculate_xy_radius(m);
if (m->tex)
free(m->tex);
m->tex = malloc(sizeof(*m->tex) * m->ntriangles * 3);
if (!m->tex)
return;
for (i = 0; i < m->ntriangles; i++) {
struct vertex *vtx0, *vtx1, *vtx2;
vtx0 = m->t[i].v[0];
vtx1 = m->t[i].v[1];
vtx2 = m->t[i].v[2];
u0 = vtx0->x / (r * 2.0) + 0.5;
v0 = vtx0->y / (r * 2.0) + 0.5;
u1 = vtx1->x / (r * 2.0) + 0.5;
v1 = vtx1->y / (r * 2.0) + 0.5;
u2 = vtx2->x / (r * 2.0) + 0.5;
v2 = vtx2->y / (r * 2.0) + 0.5;
mesh_set_triangle_texture_coords(m, i, u0, v0, u1, v1, u2, v2);
}
mesh_graph_dev_init(m);
}
static void mesh_uv_map_planetary_ring(struct mesh *m)
{
float u0, u1, u2, r;
int i;
r = mesh_calculate_xy_radius(m);
if (m->tex)
free(m->tex);
m->tex = malloc(sizeof(*m->tex) * m->ntriangles * 3);
if (!m->tex)
return;
for (i = 0; i < m->ntriangles; i++) {
struct vertex *vtx0, *vtx1, *vtx2;
vtx0 = m->t[i].v[0];
vtx1 = m->t[i].v[1];
vtx2 = m->t[i].v[2];
/* v will be a per-instance constant passed as uniform to the shader */
u0 = (float) outside_edge_of_ring(vtx0, r);
u1 = (float) outside_edge_of_ring(vtx1, r);
u2 = (float) outside_edge_of_ring(vtx2, r);
mesh_set_triangle_texture_coords(m, i, u0, 0.0f, u1, 0.0f, u2, 0.0f);
}
mesh_graph_dev_init(m);
}
/* this has a known issue mapping vertices of tris that span the "international date line" */
void mesh_sphere_uv_map(struct mesh *m)
{
float u0, v0, u1, v1, u2, v2;
int i;
if (m->tex)
free(m->tex);
m->tex = malloc(sizeof(*m->tex) * m->ntriangles * 3);
if (!m->tex)
return;
for (i = 0; i < m->ntriangles; i++) {
struct vertex *vtx0, *vtx1, *vtx2;
vtx0 = m->t[i].v[0];
vtx1 = m->t[i].v[1];
vtx2 = m->t[i].v[2];
u0 = acosf(vtx0->z) / M_PI;
v0 = (atan2f(vtx0->y, vtx0->x) + M_PI) / (2.0 * M_PI);
u1 = acosf(vtx1->z) / M_PI;
v1 = (atan2f(vtx1->y, vtx1->x) + M_PI) / (2.0 * M_PI);
u2 = acosf(vtx2->z) / M_PI;
v2 = (atan2f(vtx2->y, vtx2->x) + M_PI) / (2.0 * M_PI);
mesh_set_triangle_texture_coords(m, i, u0, v0, u1, v1, u2, v2);
}
mesh_graph_dev_init(m);
}
/* This is not very good, but better than nothing. */
void mesh_random_uv_map(struct mesh *m)
{
int i;
if (m->tex)
free(m->tex);
m->tex = malloc(sizeof(*m->tex) * m->ntriangles * 3);
if (!m)
return;
for (i = 0; i < m->ntriangles; i++) {
float u1, v1, u2, v2, u3, v3;
u1 = (float) snis_randn(25) / 100.0f;
v1 = (float) snis_randn(25) / 100.0f;
u2 = (float) (50.0f + snis_randn(25)) / 100.0f;
v2 = (float) snis_randn(25) / 100.0f;
u3 = (float) (50.0f + snis_randn(25)) / 100.0f;
v3 = (float) (50.0f + snis_randn(25)) / 100.0f;
mesh_set_triangle_texture_coords(m, i, u1, v1, u2, v2, u3, v3);
}
}
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;
}
