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// https://stackoverflow.com/questions/785097/how-do-i-implement-a-bézier-curve-in-c | |
vector_3 getBezierPoint(vector<vector_3> points, float t ) | |
{ | |
int i = points.size() - 1; | |
while (i > 0) | |
{ | |
for (int k = 0; k < i; k++) | |
{ | |
points[k].x = points[k].x + t * ( points[k+1].x - points[k].x ); | |
points[k].y = points[k].y + t * ( points[k+1].y - points[k].y ); | |
points[k].z = points[k].z + t * ( points[k+1].z - points[k].z ); | |
} | |
i--; | |
} | |
return points[0]; | |
} | |
// ... | |
vector<vector_3> pos; | |
vector_3 v0(-0.5, 0.5, 0); | |
vector_3 v1( 0.5, 0.5, 0); | |
vector_3 v2( 0.5, -0.5, 0); | |
vector_3 v3( -1.0, -1.0, 0); | |
pos.push_back(v0); | |
pos.push_back(v1); | |
pos.push_back(v2); | |
pos.push_back(v3); | |
vector<vector_3> v; | |
vector<vector_3> deriv; | |
for(float t = 0; t <= 1; t += 0.1) | |
{ | |
vector_3 vline = getBezierPoint(pos, t); | |
v.push_back(vline); | |
if(t == 1) | |
deriv.push_back(getBezierPoint(pos, t - 0.001)); | |
else | |
deriv.push_back(getBezierPoint(pos, t + 0.001)); | |
} | |
glLineWidth(2.0f); | |
glBegin(GL_LINE_STRIP); | |
for(size_t i = 0; i < v.size(); i++) | |
glVertex3f(v[i].x, v[i].y, v[i].z); | |
glEnd(); | |
glColor3f(1, 0.5, 0); | |
glBegin(GL_LINES); | |
for(size_t i = 0; i < deriv.size(); i++) | |
{ | |
vector_3 line = deriv[i] - v[i]; | |
line.normalize(); | |
glVertex3f(v[i].x, v[i].y, v[i].z); | |
glVertex3f(v[i].x + line.x, v[i].y + line.y, v[i].z + line.z); | |
} | |
glEnd(); |
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