void createMeshStripIndices(void) {
int n=0;
int i,j;
for (i=0; i< BIG_N; i++) {
for (j=0; j<= BIG_M; j++) {
tubeStrips[n++] = VERTEX_INDEX(i,j);
tubeStrips[n++] = VERTEX_INDEX((i+1) % (BIG_N+1),j);
}
tubeStrips[n] = tubeStrips[n-1];
n++;
tubeStrips[n] = tubeStrips[n-2];
n++;
tubeStrips[n] = VERTEX_INDEX(i,j);
n++;
tubeStrips[n] = VERTEX_INDEX(i,j);
n++;
}
while (n!= TOTAL_INDICES-1) {
n--;
}
}
void buildTube(){
static GLboolean firstTime = GL_TRUE;
if( firstTime ) {
glGenBuffers(1,&vertexBuffer);
glGenBuffers(1,&indexBuffer);
glGenBuffers(1,&normalBuffer);
/* Fill and buffer index data, since its done only once */
int n = 0;
int i, j;
for ( i = 0; i < TUBE_N; i++ ) {
for( j = 0; j < TUBE_M; j++ ) {
tubeStrips[n++] = VERTEX_INDEX((i+1)%TUBE_N,j);
tubeStrips[n++] = VERTEX_INDEX(i,j);
}
tubeStrips[n++] = VERTEX_INDEX((i+1)%TUBE_N,0);
tubeStrips[n++] = VERTEX_INDEX(i,0);
}
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(tubeStrips), tubeStrips, GL_STATIC_DRAW);
firstTime = GL_FALSE;
}
double dt = (2*M_PI)/TUBE_N;
double du = (2*M_PI)/TUBE_M;
/* Calculate Points */
double t;
int i;
for(i = 0, t = 0.0; i < TUBE_N; i++, t += dt ){
GLdouble C[3], T[3], A[3], B[3], N[3];
/* x, y, z */
C[0] = ( a + b*cos(q*t)) * cos(p*t);
C[1] = ( a + b*cos(q*t)) * sin(p*t);
C[2] = b * sin(q*t);
/* dx, dy, dz */
T[0] = -p*C[1] - b*q*sin(q*t)*cos(p*t);
T[1] = p*C[0] - b*q*sin(q*t)*sin(p*t);
T[2] = b*q*cos(q*t);
/* ddx, ddy, ddz */
A[0] = -p*T[1] + b*q*(p*sin(q*t)*sin(p*t) - q*cos(q*t)*cos(p*t));
A[1] = p*T[0] - b*q*(p*sin(q*t)*cos(p*t) + q*cos(q*t)*sin(p*t));
A[2] = -(q*q)*b*sin(q*t);
/* B = T cross A */
B[0] = T[1]*A[2] - T[2]*A[1];
B[1] = T[2]*A[0] - T[0]*A[2];
B[2] = T[0]*A[1] - T[1]*A[0];
/* Normalize T and B */
normalize(T);
normalize(B);
/* N = B cross T */
N[0] = B[1]*T[2] - B[2]*T[1];
N[1] = B[2]*T[0] - B[0]*T[2];
N[2] = B[0]*T[1] - B[1]*T[0];
//normalize(N);
float u;
int j;
for( j = 0, u = 0.0; j < TUBE_M; j++, u += du ){
for( int k = 0; k < 3; k++ ){
tubeNormals[i][j][k] = cos(u)*B[k] + sin(u)*N[k];
tube[i][j][k] = C[k] + R*tubeNormals[i][j][k];
}
}
}
/* Load vertex buffer */
glBindBuffer(GL_ARRAY_BUFFER, normalBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(tubeNormals), tubeNormals, GL_DYNAMIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(tube), tube, GL_DYNAMIC_DRAW);
}
