void project_to_isosurface(Vec3f& point, const float target_value, const Array3f& grid, const Vec3f& origin, const float dx) {
float tol = 0.01f*dx; //some fraction of a grid cell;
int max_iter = 5;
int iter = 0;
Vec3f normal;
float phi = interpolate_normal(normal, point, grid, origin, dx);
while(fabs(phi - target_value) > tol && iter++ < max_iter) {
point -= (phi - target_value) * normal;
phi = interpolate_normal(normal, point, grid, origin, dx);
}
}
void render_quarter(int n)
{
int i, j;
GLfloat step = 1.0/((GLfloat)n-1);
GLfloat x[2];
GLfloat y[2];
GLfloat normal[2][2][3];
for(i = 0 ; i < n-1 ; i++)
{
for(j = 0 ; j < n-1 ; j++)
{
x[0] = step*((GLfloat)i);
x[1] = step*((GLfloat)(i+1));
y[0] = step*((GLfloat)j);
y[1] = step*((GLfloat)(j+1));
interpolate_normal(x[0],y[0],normal[0][0]);
interpolate_normal(x[0],y[1],normal[0][1]);
interpolate_normal(x[1],y[0],normal[1][0]);
interpolate_normal(x[1],y[1],normal[1][1]);
#define SET_VERT(ix,iy) \
glNormal3fv(normal[ix][iy]); \
glVertex3f(x[ix],y[iy],0);
#define SCALE .2
if(flag & FLAG_NORMAL)
{
glDisable(GL_LIGHTING);
glColor3f(1,1,1);
glBegin(GL_LINES);
glVertex3f(x[0],y[0],0); glVertex3f(x[0]+SCALE*normal[0][0][0], y[0]+SCALE*normal[0][0][1], SCALE*normal[0][0][2]);
glVertex3f(x[0],y[1],0); glVertex3f(x[0]+SCALE*normal[0][1][0], y[1]+SCALE*normal[0][1][1], SCALE*normal[0][1][2]);
glVertex3f(x[1],y[0],0); glVertex3f(x[1]+SCALE*normal[1][0][0], y[0]+SCALE*normal[1][0][1], SCALE*normal[1][0][2]);
glVertex3f(x[1],y[1],0); glVertex3f(x[1]+SCALE*normal[1][1][0], y[1]+SCALE*normal[1][1][1], SCALE*normal[1][1][2]);
glEnd();
glEnable(GL_LIGHTING);
}
glBegin(GL_QUADS);
SET_VERT(0,0);
SET_VERT(1,0);
SET_VERT(1,1);
SET_VERT(0,1);
glEnd();
}
}
}
bool
SmoothUVMeshTriangle::hit(const Ray& ray, double& tmin, ShadeRec& sr) const {
Point3D v0(mesh_ptr->vertices[index0]);
Point3D v1(mesh_ptr->vertices[index1]);
Point3D v2(mesh_ptr->vertices[index2]);
double a = v0.x - v1.x, b = v0.x - v2.x, c = ray.d.x, d = v0.x - ray.o.x;
double e = v0.y - v1.y, f = v0.y - v2.y, g = ray.d.y, h = v0.y - ray.o.y;
double i = v0.z - v1.z, j = v0.z - v2.z, k = ray.d.z, l = v0.z - ray.o.z;
double m = f * k - g * j, n = h * k - g * l, p = f * l - h * j;
double q = g * i - e * k, s = e * j - f * i;
double inv_denom = 1.0 / (a * m + b * q + c * s);
double e1 = d * m - b * n - c * p;
double beta = e1 * inv_denom;
if (beta < 0.0)
return (false);
double r = e * l - h * i;
double e2 = a * n + d * q + c * r;
double gamma = e2 * inv_denom;
if (gamma < 0.0)
return (false);
if (beta + gamma > 1.0)
return (false);
double e3 = a * p - b * r + d * s;
double t = e3 * inv_denom;
if (t < kEpsilon)
return (false);
tmin = t;
sr.normal = interpolate_normal(beta, gamma); // for smooth shading
//sr.local_hit_point = ray.o + t * ray.d;
sr.u = interpolate_u(beta, gamma);
sr.v = interpolate_v(beta, gamma);
return (true);
}
void surface_fractal_terrain::generate_mesh(const std::vector<std::vector<double> > &height, int size, double sidelen) {
double scale = sidelen / size, delta = 1.0 / size;
std::vector<point3D> vertices;
#define __id(i, j) ((i) * (size + 1) + (j))
for (int i = 0; i <= size; ++i) {
for (int j = 0; j <= size; ++j) {
vertices.push_back(point3D(i * scale, j * scale, height[i][j]));
}
}
setup_vertex(vertices);
for (int i = 0; i < size; ++i) {
for (int j = 0; j < size; ++j) {
double u = i * delta, v = j * delta;
add_surface(__id(i, j), __id(i + 1, j), __id(i, j + 1)).set_UV(point2D(u, v), point2D(u + delta, v), point2D(u, v + delta));
add_surface(__id(i + 1, j), __id(i + 1, j + 1), __id(i, j + 1)).set_UV(point2D(u + delta, v), point2D(u + delta, v + delta), point2D(u, v + delta));
}
}
#undef __id
setup_tree();
interpolate_normal();
}