b-spline曲線範例程式

//--------------------------------------------------------------------------- #include <vcl.h> #pragma hdrstop #include "BSplineEasy0.h" #include <math.h> //--------------------------------------------------------------------------- #pragma package(smart_init) #pragma resource "*.dfm" TForm1 *Form1; //--------------------------------------------------------------------------- __fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner) { } struct Vertex { int x, y; void set(int nx, int ny) { x=nx; y=ny; } void set(float nx, float ny) { x=nx; y=ny; } }; bool getVertex = false; bool pressing = false; int upx, upy, dnx, dny; class BSpline { protected: int mPoints; float t[4], n[4]; Vertex *mVertex; public: BSpline() { mVertex = NULL; } void setLength(int len) { mPoints = len; } void computeN(); void computeT(float param); void assign(Vertex * av, int points) { mVertex=av; mPoints=points; } void draw(TCanvas *canvas, int start=0); void closeDraw(TCanvas *canvas); }; void BSpline::closeDraw(TCanvas *canvas) { float s, x, y; int k, p, c; canvas->Pen->Mode = pmNot; for (p=0; p<mPoints-3; p++) { x = (mVertex[p].x+4*mVertex[p+1].x+mVertex[p+2].x)/6.; y = (mVertex[p].y+4*mVertex[p+1].y+mVertex[p+2].y)/6.; canvas->MoveTo(x, y); for (s=0.1; s<=1.05; s+=0.05) { computeT(s); computeN(); x=y=0.0; for (k=0; k<4; k++) { x += n[k]*mVertex[p+k].x; y += n[k]*mVertex[p+k].y; } canvas->LineTo(x, y); } } // for closing the path for (c=0; c<3; c++) { x = (mVertex[(p)%mPoints].x+4*mVertex[(p+1)%mPoints].x+mVertex[(p+2)%mPoints].x)/6.; y = (mVertex[(p)%mPoints].y+4*mVertex[(p+1)%mPoints].y+mVertex[(p+2)%mPoints].y)/6.; canvas->MoveTo(x, y); for (s=0.1; s<=1.05; s+=0.05) { computeT(s); computeN(); x=y=0.0; for (k=0; k<4; k++) { x += n[k]*mVertex[(p+k)%mPoints].x; y += n[k]*mVertex[(p+k)%mPoints].y; } canvas->LineTo(x, y); } p++; } } void BSpline::draw(TCanvas *canvas, int start) { float s, x, y; int k; canvas->Pen->Mode = pmNot; x = (mVertex[start].x+4*mVertex[start+1].x+mVertex[start+2].x)/6.; y = (mVertex[start].y+4*mVertex[start+1].y+mVertex[start+2].y)/6.; canvas->MoveTo(x, y); for (s=0.1; s<=1.0; s+=0.01) { computeT(s); computeN(); x=y=0.0; for (k=0; k<4; k++) { x += n[k]*mVertex[start+k].x; y += n[k]*mVertex[start+k].y; } //Sleep(1); canvas->LineTo(x, y); } } void BSpline::computeT(float param) { t[0] = 1.0; t[1] = param; t[2] = param*param; t[3] = t[2]*param; } void BSpline::computeN() { n[3] = t[3]/6.; n[2] = t[3]*(-0.5) + (t[2]+t[1])*0.5 + 1./6.; n[1] = t[3]*0.5 - t[2] + 4./6.; n[0] = (-t[3]+3*(t[2]-t[1])+1)/6.; } const int Points = 10; BSpline bs; Vertex vt[Points]; int index=0; //--------------------------------------------------------------------------- void __fastcall TForm1::Button1Click(TObject *Sender) { if ( !getVertex ) { getVertex = true; index = 0; Button1->Caption = "Stop"; } else { getVertex = false; Button1->Caption = "Get control points"; } } //--------------------------------------------------------------------------- void __fastcall TForm1::FormMouseDown(TObject *Sender, TMouseButton Button, TShiftState Shift, int X, int Y) { if ( getVertex ) { if ( index<Points ) { vt[index].x = X; vt[index].y = Y; Canvas->Brush->Style = bsSolid; Canvas->Pen->Mode = pmNot; Canvas->Ellipse(X-2, Y-2, X+2, Y+2); index++; if ( index >= Points ) { getVertex = false; Button1->Caption = "Get control points"; return; } } } } //--------------------------------------------------------------------------- void __fastcall TForm1::Button2Click(TObject *Sender) { static from=0; bs.assign(vt, index); bs.draw(Form1->Canvas, from); from++; if ( from > index-3-1 ) from = 0; } //--------------------------------------------------------------------------- void __fastcall TForm1::Button3Click(TObject *Sender) { bs.assign(vt, index); bs.closeDraw(Form1->Canvas); } //--------------------------------------------------------------------------- void __fastcall TForm1::FormMouseUp(TObject *Sender, TMouseButton Button, TShiftState Shift, int X, int Y) { pressing = false; } //---------------------------------------------------------------------------