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我喜欢有一个程序，你可以选择十个点，然后计算出一个贝塞尔曲线。它似乎工作非常完美，但显示的曲线有一些差距。我使用GL_LINE_STRIP这些点如何不可能连接？opengl动态贝塞尔曲线有间隙 - glEvalCoord1f（）;
我想，glEvalCoord1f(u);中的一个非常小的u会使间隙变小。 u如何取决于glEvalCoord1f(u);中的控制点和窗口属性？
[编辑]添加较粗的线网： 
#include <iostream>
#include <stdlib.h>
#include <string>
#include <fstream>
#include <math.h>
#include <time.h>
#include <GL/glut.h> //added GL prefix for Ubuntu compatibility
#define MAXP 10
GLint nNumPoints = 0;
GLfloat ctrlpoints[10][3];
GLdouble mouseOgl[3] = {0.0,0.0,0.0};
GLint mouseX, mouseY;
bool mousePressed = false;
void GetOGLPos(int x, int y);
void init(void)
{
glClearColor(1.0, 1.0, 1.0, 0.0);
glShadeModel(GL_FLAT);
// Enable the evaluator
glEnable(GL_MAP1_VERTEX_3);
glEnable(GL_DEPTH);
}
void display(void)
{
int i;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f(0.0, 0.0, 1.0);
if(mousePressed && nNumPoints < MAXP){
GetOGLPos(mouseX, mouseY);
std::cout
<< mouseOgl[0] << " # "
<< mouseOgl[1] << " # "
<< mouseOgl[2] << " # "
<< std::endl;
nNumPoints++;
ctrlpoints[nNumPoints-1][0] = mouseOgl[0];
ctrlpoints[nNumPoints-1][3] = mouseOgl[1];
ctrlpoints[nNumPoints-1][2] = mouseOgl[2];
}
//Curves
if(nNumPoints == MAXP){
glMap1f(GL_MAP1_VERTEX_3, // Type of data generated
0.0f, // Lower u range
1.0f, // Upper u range
3, // Distance between points in the data 3: ...Z-X-Y-Z...
nNumPoints, // number of control points
&ctrlpoints[0][0]); // start point
glBegin(GL_LINE_STRIP);
float max = pow(MAXP,4)*2; //accuracy of pint calulation?
for (i = 0; i <= max; i++)
glEvalCoord1f((GLfloat) (i/max)); //high value to avoid gaps?!?
glEnd();
}
//Controllpoints:
glPointSize(5.0);
glColor3f(1.0, 0.0, 0.0);
glBegin(GL_POINTS);
for (i = 0; i < nNumPoints; i++)
glVertex3fv(&ctrlpoints[i][0]);
glEnd();
//Lines
glColor3f(0.0, 1.0, 0.0);
glBegin(GL_LINE_STRIP);
for (i = 0; i < nNumPoints; i++)
glVertex3fv(&ctrlpoints[i][0]);
glEnd();
if(nNumPoints == MAXP){nNumPoints = 0;}
glFlush();
}
void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//keep aspect ratio:
if (w <= h)
glOrtho(-2.0, 2.0, -2.0*(GLfloat)h/(GLfloat)w,
2.0*(GLfloat)h/(GLfloat)w, -2.0, 2.0);
else
glOrtho(-2.0*(GLfloat)w/(GLfloat)h,
2.0*(GLfloat)w/(GLfloat)h, -2.0, 2.0, -2.0, 2.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
//handle click events of the mouse
void myMouse(int button, int state, int x, int y)
{
//mouse coords to gl coords
mouseX = x;
mouseY = y;
switch (button)
{
case GLUT_LEFT_BUTTON:
if(state == GLUT_UP){ //on release left mouse button
std::cout << x << " * "<< y << std::endl;
mousePressed = true;
glutPostRedisplay(); //redisplay and calculate gl coords
} else {
mousePressed = false;
}
break;
}
}
// detailed information:
// http://nehe.gamedev.net/article/using_gluunproject/16013/
void GetOGLPos(int x, int y)
{
//init vars:
GLint viewport[4];
GLdouble modelview[16];
GLdouble projection[16];
GLfloat winX, winY, winZ;
GLdouble posX, posY, posZ;
//get gl specs
glGetDoublev(GL_MODELVIEW_MATRIX, modelview); //get Modelmatrix
glGetDoublev(GL_PROJECTION_MATRIX, projection); //get projection matrix
glGetIntegerv(GL_VIEWPORT, viewport); //get viewport values
//calculate the gl mouseposition
winX = (float)x;
winY = (float)viewport[3] - (float)y;
glReadPixels(x, int(winY), 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ);
gluUnProject(winX, winY, winZ, modelview, projection, viewport, &posX, &posY, &posZ);
mouseOgl[0] = posX;
mouseOgl[1] = posY;
mouseOgl[2] = posZ;
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize (600, 600);
glutInitWindowPosition (100, 100);
glutCreateWindow (argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMouseFunc(myMouse);
glutMainLoop();
return 0;
}
屏幕提供，这样可以很清楚的我改变了“float max = pow（MAXP，4）* 2;”到“float max = pow（MAXP，2）* 2;” – abimelex
你能增加蓝线的大小吗？ –
我可以，但它不能解决问题。或者你需要它作为屏幕？ – abimelex