/*! \brief intersect a ray with a sphere, only returns the first intersection point
*/
Intersection_t *Intersect_Sphere(Rayf_t *ray, Geo_Sphere_t *sphere) {
/* values for the quadric equation */
float a = LengthSqV3f(ray->dir);
float b = 2 * DotV3f(ray->dir, ray->orig);
float c = LengthSqV3f(ray->orig) - Sqrf(sphere->radius);
float D = Sqrf(b) - (4 * a * c);
if (D >= 0) {
float t1 = (-b - sqrtf(D)) / (2 * a), t2 = (-b + sqrtf(D)) / (2 * a); /* two candidate intersection parameters */
float t; /* the smallest positive candidate intersection parameter */
/* if only 1 is negative the ray starts inside the sphere
* if both are negative the sphere is behind the ray
* either way there's no intersection
*/
if (t1 <= EPSILON || t2 <= EPSILON)
return NULL;
else if (t1 <= EPSILON)
t = t2;
else if (t2 <= EPSILON)
t = t1;
else
t = Minf(t1, t2);
Intersection_t *intersection = NEW(Intersection_t);
intersection->t = t;
RayToPointf(ray, t, intersection->point);
/* for a sphere centered at the origin the normal of a point is the vector from the point to the origin */
CopyV3f(intersection->point, intersection->norm);
NormalizeV3f(intersection->norm);
/* compute texture coordinates */
intersection->u = ((atan2(intersection->norm[1], intersection->norm[0]) / 3.142) + 1) / 2;
intersection->v = (intersection->norm[2] + 1) / 2;
return intersection;
}
return NULL;
}
void Graphics::render(TrackData_t *track)
{
if (!initialized) {
error->log(GRAPHICS, IMPORTANT, "Render function called without graphics initialization\n");
return;
}
if (track) {
int i, j;
/* load in the vertices */
Vec3f_t vert;
GLUquadricObj *quadobj = gluNewQuadric();
Vec3f_t v;
Segment_t *seg;
int len;
float ang;
glColor3f(1,1,0);
glBegin(GL_LINES);
for (i = 0; i < track->nLanes; i++)
{
for (j = 0; j < track->lanes[i].nSegs; j++)
{
seg = &track->lanes[i].segs[j];
switch (track->lanes[i].segs[j].kind) {
case LINE_SEGMENT:
CopyV3f(track->verts[seg->start], vert);
glVertex3f(vert[0], vert[1] + .01, vert[2]);
CopyV3f(track->verts[seg->end], vert);
glVertex3f(vert[0], vert[1] + .01, vert[2]);
break;
case ARC_SEGMENT:
glEnd();
CopyV3f(track->verts[seg->center],v);
glPushMatrix();
glTranslatef(v[0], v[1] + .01, v[2]);
glRotatef(-90,1,0,0);
SubV3f(v, track->verts[seg->start], v);
len = LengthV3f(v);
ang = seg->end > seg->start ? seg->angle : -seg->angle;
gluPartialDisk(quadobj, len-.05, len, 40, 5,
0, ang);
gluPartialDisk(quadobj, len-.05, len, 40, 5,
0, ang);
glPopMatrix();
glBegin(GL_LINES);
break;
}
}
}
glEnd();
gluDeleteQuadric(quadobj);
/* draw finish line */
glDisable(GL_LIGHTING);
glColor3f(1,0,1);
glLineStipple(1, 0x0C0F);
glLineWidth(4);
glBegin(GL_LINES);
glVertex3fv(track->verts[track->sects[0].edges[0].start]);
glVertex3fv(track->verts[track->sects[0].edges[1].start]);
glEnd();
glLineWidth(1);
glDisable(GL_LINE_STIPPLE);
glEnable(GL_LIGHTING);
}
}
