Algorithms

typedef struct tagBezier{
    float x, y;         // Curve position
    POINTF P0, P1, P2;  // Control points
    float t, t2;        // Time variable [0-1]
} Bezier;

void CViz3D::calculateBezier(Bezier& b, float time) {
    b.t2 = b.t;  b.t = time;

    b.x = (pow(b.P0.x*(1 - b.t),2) + b.P1.x*2*b.t*(1 - b.t) + pow(b.P2.x*b.t,2));
    b.y = (pow(b.P0.y*(1 - b.t),2) + b.P1.y*2*b.t*(1 - b.t) + pow(b.P2.y*b.t,2));
}

void CViz3D::drawBezierCurve(Bezier b[CURVES]) {
    float iStart = 0, iEnd = 1;

    if (b[start].t < b[start].t2) {  // Change position if finished
        int sOld = start;   // Previous start pos
        start = (start+1)%CURVES;
        end = (end+1)%CURVES;
        float distX=b[sOld].P2.x-b[sOld].P1.x, distY=b[sOld].P2.y-b[sOld].P1.y;
        b[start].P0.x = b[sOld].P2.x;       b[start].P0.y = b[sOld].P2.y;
        b[start].P1.x = b[sOld].P2.x+distX; b[start].P1.x = b[sOld].P2.y+distY;
        b[start].P2.x = (RAND-0.5f);        b[start].P2.y = (RAND-0.5f);
    }

    for (int j = 0; j < CURVES; j++) {
        if (j == start) {  iStart = 0;  iEnd = bezTime; }
        else if (j == end){ iStart = bezTime; iEnd = 1; }
        else { iStart = 0; iEnd = 1; }

        glBegin(GL_LINE_STRIP);
        for (float i = iStart; i < iEnd; i += 0.01f) {
            calculateBezier(b[j], i);
            glVertex2f(b[j].x, b[j].y);
        }
        glEnd();
    }
}