Point de_casteljau(Point* control, int i, int r, double t, int start) {
if (r == 0) {
return control[i+start]; // Retorna o ponto do nivel adequado
} else {
Point g = de_casteljau(control, i, r-1, t, start);
Point h = de_casteljau(control, i+1, r-1, t, start);
Point k;
k.setCoordXY((1-t)*g.x + t*h.x, (1-t)*g.y + t*h.y);
return k;
}
}
Points* render::bezier(Bezier *curve) {
Points *ret = new Points;
for (float dt = 0, inc = 1.0/float(curve->res); dt <= 1.0; dt += inc)
ret->push_back(de_casteljau(curve->points, dt));
return ret;
}
void draw_curve() {
Point P, Q;
int L = qpoints - 3;
if (numpoints <= 4) {
float par = 0;
while (par <= 1) {
Q = de_casteljau(control_points, 0, numpoints-1, par, 0);
glBegin(GL_POINTS);
glColor3f(0.0f, 0.0f, 237.0f);
glVertex2f(Q.x, Q.y);
glEnd();
if (par > 0) {
glBegin(GL_LINES);
glColor3f(0.0f, 0.0f, 237.0f);
glVertex2f(Q.x, Q.y);
glVertex2f(P.x, P.y);
glEnd();
}
P.setCoordXY(Q.x, Q.y);
par += float(1)/float(factor);
}
} else {
float par = 0;
GLfloat u;
for (int i = 0; i < L; i++) {
u = us[i];
while (u <= us[i+1]) {
par = (u - us[i])/(us[i+1] - us[i]); // Parametrização
if (i != L-1) {
Q = de_casteljau(control_points, 0, 3, par, 3*i);
} else {
Q = de_casteljau(control_points, 0, numpoints - (1 + 3*i), par, 3*i);
}
glBegin(GL_POINTS);
glColor3f(0.0f, 0.0f, u);
glVertex2f(Q.x, Q.y);
glEnd();
// Liga um segmento de reta entre dois pontos consecutivos da curva
if (u > us[0]) {
glBegin(GL_LINES);
glColor3f(0.0f, 0.0f, u);
glVertex2f(Q.x, Q.y);
glVertex2f(P.x, P.y);
glEnd();
}
P.setCoordXY(Q.x, Q.y);
u += (us[L]-us[0])/float(factor); // Divide o intervalo de acordo com o fator escolhido pelo usuario apertando (+/-)
}
}
// Ultimo ponto da curva
glBegin(GL_LINES);
glColor3f(0.0f, 0.0f, u);
glVertex2f(control_points[(3*L)].x, control_points[(3*L)].y);
glVertex2f(P.x, P.y);
glEnd();
}
}
