int ParticleSystem::createSphere(int numParticles, float maxspray, Vertices &vtx, Indices &ind)
{
int i;
Vector3f pos;
Vector3f norm;
Vector2f texCoord;
Vector4f colour;
Vector3f wander;
vtx.resize(numParticles);
std::cout << " the vector's size is: " << vtx.size() << std::endl;
std::cout << " the vector's capacity is: " << vtx.capacity() << std::endl;
std::cout << " the vector's maximum size is: " << vtx.max_size() << std::endl;
ind.resize(0);
srand(time(0));
float trad = 0.4; // Defines the starting point of the particles
/* Create a set of points which will be the particles */
/* This is similar to drawing a torus: we will sample points on the surface of the torus */
float u, v, w, theta, phi, spray; // Work variables
for (int i = 0; i < numParticles; i++){
// Randomly select two numbers to define a point on the torus
u = ((double) rand() / (RAND_MAX));
v = ((double) rand() / (RAND_MAX));
// Use u and v to define the point on the torus
theta = u * 2.0f*M_PI;
phi = v * 2.0f*M_PI;
norm = Vector3f(cos(theta)*cos(phi), sin(theta)*cos(phi), sin(phi));
pos = Vector3f(norm.x*trad, norm.y*trad, norm.z*trad);
colour = Vector4f(((float)i) / ((float)numParticles), 0.0f, 1.0f - (((float)i) / ((float)numParticles)), 1.0f);
texCoord = Vector2f(0, 0); //not used for particels
// Now sample a point on a sphere to define a direction for points to wander around
u = ((double) rand() / (RAND_MAX));
v = ((double) rand() / (RAND_MAX));
w = ((double) rand() / (RAND_MAX));
theta = u * 2*M_PI;
phi = acos(2.0*v * -1.0);
spray = maxspray*pow((float) w, (float) (1.0/3.0)); // Cubic root
wander = Vector3f(spray*sin(theta)*sin(phi), spray*cos(theta)*sin(phi), spray*cos(phi));
norm = wander;
vtx[i] = Vertex(pos, colour, norm, texCoord);
}
return(0);
}
int Sphere::createSphere(int numLong, int numLat, Vertices &vtx, Indices &ind, Vector4f colour)
{
int i, j, k;
int numRows;
int numCols;
int numVtx;
int numTriangles;
Vector3f pos;
Vector4f col;
Vector3f norm;
Vector2f texCoord;
float alpha;
float beta;
float deltaAlpha;
float deltaBeta;
Vector4f noColour = (-1, -1, -1, -1);
numRows = numLat * 2; // number of horizonal slabs
numCols = numLong; // number of vertical slabs
numVtx = (numRows + 1) * (numCols + 1);
vtx.resize(numVtx);
cout << " the vector's size is: " << vtx.size() << endl;
cout << " the vector's capacity is: " << vtx.capacity() << endl;
cout << " the vector's maximum size is: " << vtx.max_size() << endl;
numTriangles = numRows * numCols * 2;
ind.resize(numTriangles * 3);
// Fill the vertex buffer with positions
k = 0;
alpha = 0.0f; // angle of latitude starting from the "south pole"
deltaAlpha = (float)90.0 / numLat; // increment of alpha
beta = 0; // angle of the longtidute
deltaBeta = (float)360.0 / (numLong); // increment of beta
float dTexX = 1.0 / numCols;
float dTexY = 1.0 / numRows;
for (i = 0, alpha = -90; i <= numRows; i++, alpha += deltaAlpha) {
for (j = 0, beta = 0; j <= numCols; j++, beta += deltaBeta) {
pos.x = cos(DegreeToRadians(alpha))*cos(DegreeToRadians(beta));
pos.y = cos(DegreeToRadians(alpha))*sin(DegreeToRadians(beta));
pos.z = sin(DegreeToRadians(alpha));
//spheres normals are just the point - the center, but the center is at 0,0 so we just normalize the point
norm = Vector3f(pos.x, pos.y, pos.z);
norm.normalize();
texCoord = Vector2f(j*dTexX, i*dTexY);
if (colour == noColour){
vtx[k] = Vertex(pos, Vector4f(pos, 1.0), norm, texCoord);
}
else{
vtx[k] = Vertex(pos, colour, norm, texCoord);
}
k++;
}
}
// fill the index buffer
k = 0;
for (i = 0; i < numRows; i++) {
for (j = 0; j < numCols; j++) {
// fill indices for the quad
// change by making a quad function
ind[k++] = i * (numCols + 1) + j;
ind[k++] = i * (numCols + 1) + j + 1;
ind[k++] = (i + 1) * (numCols + 1) + j + 1;
ind[k++] = i * (numCols + 1) + j;
ind[k++] = (i + 1) * (numCols + 1) + j + 1;
ind[k++] = (i + 1) * (numCols + 1) + j;
}
}
return(0);
}
